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543 Cards in this Set
- Front
- Back
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What forms the roof of the fourth ventricle?
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Superior peduncles
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Where is the medial longitudinal fasculus located and what is it involved in?
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It is located near the floor of the fourth ventricle poserior to the medial lemniscus. It coordinates head and eye movements.
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Where does the inferior olivary nucleus end?
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At the caudal pons
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What does the medial lemniscal tract join with?
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Spinothalamic tract
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What are cell bodies called in the CNS?
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Nuclei, which aggregate into bodies in the grey matter.
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What are cell bodies called in the PNS?
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Ganglia
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Where are the GnRH neurosecratory cells derived from?
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The olfactory placode (NOT neuroepithelium) and migrated down the terminal nerve (cranial nerve 0) into the forebrain.
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What is the retina a derivative of?
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Diencephalon
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What is the function of the subthalamus?
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Has sensory tracts that proceed to the thalamus and has the subthlamic nucleus that has motor functions.
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What is the telencephalon composed of?
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cerebral cortex, corpus striatum and cerebral white matter
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What is the corpus striatum?
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Large mass of grey matter near the base of each hemisphere.
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What is the corpus striatum?
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Large mass of grey matter with motor fuction located at the base of each hemisphere
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What is the corpus striatum composed of?
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Caudate nucleus, lenticular nucleus, white matter of corpus callosum, and internal capsule
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What are golgi type II neurons?
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Neurons that contact principal neurons, i.e interneurons, internucial
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What ar neurofilaments?
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structural proteins, when gathered together they form neurofibrils.
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What are microtubules?
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25nm, rapid transport of protein molecules and small particles
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What are microfilaments?
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4nm, contractile protein actin, growing tips of neurites
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What is myelin composed of?
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closely apposed layers of glial plasma membranes
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What are grey's type 1 synapses?
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Usually excitatory, spherical
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What are Greys type 2 synapses?
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Usually ellipsoidal and inhibatory, GABA
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What are astrocytes?
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Contiain glial fibrillary acidic protein (GFAP) and have perivascular end feet facing capillaries and end feet facing pia mater to forming the internal and external glial limiting membranes
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What produces CSF?
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The choroid plexus lined with ependymal cells
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What is a mesaxon?
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A double layer of surface membraneof a schwann cell that suspends an axon
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What are satellite cells?
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Ganglionic gliocytes that surround neuronal somata.
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Where are satellite cells found?
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Sensory and autonomic ganglia.
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What is an extrafusal muscle fiber?
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Muscle fiber innervated by alpha motor neurons and serve in contraction
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What is an intrafusal muscle fiber
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Fiber innervated by gamma motor neurons and serve as a sensory proprioceptor.
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What are the largest, most rapidly conducting fibers?
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Those that innervate extrafusal muscle fibers or touch proprioception, touch, and vibration.
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What is innervated by the smallest, slowest axons?
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Pain, olfaction and visceral
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What is the synaptic transmitter in the neuromuscular junction?
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Acetylcholine
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What are varicosities?
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unmyelinated swellings of the endings of autonomic axons containing a variety of chemical transmitters.
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What are extroceptors?
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Receptors for pain, temperature, touch and pressue
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What are peritrichial nerve endings?
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Cagelike formations that surround hair follicles. Sends branches to many hair follicles - each follicle is supplied by 2 to 20 axons
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What is the physiology of myasthenia gravis?
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Auto-immune response that produces antibodies that attach to post synaptic ACh receptors in muscles
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What does the choroidal artery supply?
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optic tracts and parts of the internal capusule
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What is the path of the recurrent artery of Heubner?
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supplies the corpus striatum, internal capsule and anterior communicating artery and continues to supply the medial and super surfaces of the frontal and parietal lobes
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Where do aneurysms commonly occur?
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At sites of arterial bifurcation in an near circle of willis
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What are the terminal branches of the internal corotid artery?
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Anterior cerebral and middle cerebral
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Where does the internal corotid artery enter the cranial vault?
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foramen lacerum
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What artery supplies the posterior pituitary?
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Brances off the cavernous segment of the internal corotid which travel with the abducens nerve. (meningohypophyseal artery)
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What are the terminal branches of the supraclinoid segment of the internal carotid artery?
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Anterior and middle cerebral arteries
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What are the three branches of the supraclinoid segment of the internal carotid artery?
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opthalmic artery, posterior communicating artery, and anterior choroidal artery
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What artery does the ophthalmic artery anastamose with?
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maxillary artery branches
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Where does the anterior choroidal artery arise from?
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Supraclinoid segment of internal corotid
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What does the anterior choroidal artery supply?
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Optic tract, posterior internal capsule, midbrain and lateral geniculate nucleus
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What connects the anterior circulatory system to the posterior circulatory system?
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The posterior communicating artery (branch of the supraclinoid segment of the internal carotid)
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What does the posterior communicating artery supply?
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thalamus, hypothalamus, optic chiasm, and mamillary bodies
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Where does the anterior cerebral artery end?
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The a5 segment ends at the parietooccipital sulcus
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What might a patient with anterior cerebral artery damage experience?
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Since it supplies blood to the medial cortex (medial motor and sensory strip) it can cause sensory and motor impairment to the lower body, i.e. unilateral paralysis or incontinence
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What does the anterior cerebral artery supply?
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Most of the medial surfac of the cerebral cortex, frontal pole, and anterior corpus callosum
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What does the recurrent artery of heubner supply?
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Anterior limb of the internal capsule
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What segment of what artery is pictured?
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A1 segment of ACA
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What segment is pictured?
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anterior communicating artery
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What branch of what artery is pictured and what does it supply?
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recurrent artery of heubner supplies anterior internal capsule
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What artery is pictured and what does it supply?
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Pericollosal artery is a branch of the ACA and supplies the medial surface of the cerebral hemispheres and the corpus collosum.
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What does the middle cerebral artery supply?
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Lateral aspect of each hemisphere: speech, swallowing, language - broca's area, wernicke's area and most of the corpus striatum
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What are the central branches of the middle cerebral artery and what do they supply?
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Medial and lateral striata arteries supply the basal ganglia, internal capsule, and thalamus.
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What are the arteries of stroke?
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The striata arteries which are the main blood supply to the internl capsule. They are thin and under high pressure.
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What does occlusion of the M1 segment of the left middle cerebral artery result in?
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Global aphasia, contralateral hemiplegia of the face, arm, and leg and homonymous hemianopia. Right side does not result in aphasia
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What sement of what artery is pictured?
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M1 (horizontal) segment of MCA
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What segment of what artery is pictured and what structures does it supply?
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The lateral lenticulostiate arteries supply the basal ganglia: globus palladus, posterior portion of the internal capsule, head and body of caudate, and putamen
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What segment of what artery is pictured and what does it supply?
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The M2 segment of the MCA supplies temporal lope and insular complex (Wernike's area) and parietal lobe (sensory cortical) and inferolateral frontal lobe
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What is Sylvian (M2) segment neurovascular syndrome?
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Superior division infarction results in sensorimotor deficit of face and arm and some leg. Left lesion may result in aphasia
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What segment of what artery is pictured and what does it supply?
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The M3 (cortical) segment of the MCA supplies insular complex and the operculum
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What are the three cerebellar branches of the vertebral artery?
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"Posterior inferior - cerebellum, lateral medulla Anterior spinal - medulla Posterior spinal - medulla
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What does the vertebral artery supply?
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medulla, part of the cerebellum and the dura of the posterior fossa
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What blood vessel does the labyrinthine artery branch off of?
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Anterior inferior cerebellar
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What does the basilar artery divide to form?
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The two posterior cerebral arteries
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Where does the calcarine artery originate and what does it supply?
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It branches from the PCA and supplies all the primary and some of the association cortex for vision.
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Where do the choroidal arteries arise from and what do they supply?
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They come from both ICA and basilar system and supply the choroid plexuses and hippocampus. Blockage can affect CSF production and memory.
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How does the spinal cord get sufficient blood supply?
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The spinal arteries are not sufficient below cervical region so the spinal cord recieves the posterior intercostal branches of the thoracic aorta an lumbar branches of the abdominal aorta.
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How are the anterior and posterior spinal veins drained?
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They are drained at intervals by up to 12 anterior and 12 posterior radicular veins which empty into an epidural plexus into an external vertebral plexus. This blood empties into vertebral, intercostal and lumbar veins.
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Where do adults tend to bleed in a closed brain injury?
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The epidural space
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Where are children most likely to bleed in a closed head injury?
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Subdural space
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Where is CSF transferred back into the blood stream?
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In sinus formed by the dura mater by arachnoid granulations.
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What fills the subarachnoid space?
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CSF
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What is the pressure range for CSF?
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60-100 mmH20 or 4.4-7.3 mmHg, variations due to coughing or internal compresion of jugular veins
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What forms the choroid plexuses?
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The fusion of the pia mater and the ependyma
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What links the lateral ventricles to the third ventricle?
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Foramina of Munro or interventricular foramina
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What connects the third ventricle to the fourth ventricle?
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The cerebral aqueduct of aqeuduct of Sylvius
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What is the foramina of luschka? How many are there?
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it links the fourth ventricle to the subarachnoid space. There are two.
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What is the medial foramen of Magendie?
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It connects the subarachnoid space to the fourth ventricle along with the two lateral foramina of Luschka
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How often is CSF of the neuraxis regenerated?
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Several times a day
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What are two areas that do not have the blood brain barrier?
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The posterior pituitary and the postrema have fenestrated capillaries
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Does the ascending spinothalamic tract cross high or low?
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Low
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Do the gracilus and cuneatus tracts cross high or low?
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High
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Does the descending corticospinal tract cross high or low?
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High
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At what level is the caudal spinal cord?
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L2
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Why does the cross sectional area of white matter decrease caudally?
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The further down the spinal cord there are fewer ascending and descending fibers.
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What tracts descending motor tracts influence autonomic functions?
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Hypothalamospinal and reticulospinal tracts
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What are the major ascending tracts of the spinal cord?
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the uncrossed gracile and cuneate fasciculi from sensory ganglia and the crossed spinothalamic tract from the dorsal horn
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What are the major descending spinal tracts?
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uncrossed vestibulospinal and the crossed lateral corticospinal tract
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What are the most common dislocation points on the vertebrae?
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C5-C6, T12-L1, and C1-C2
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Where does one see ventral horn enlargment on the spinal cord?
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At segments that conrol a limb, C5-C8 and the lumbo/sacral sections.
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What is the intermediate horn?
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It is the extra cell column of the thoracic segments that is the source of sympathetic fibers.
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Where does the filum terminale attach?
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It is the pia mater that extends to anchor the spinal cord to the coccyx.
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What segments does the cervical enlargment include?
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C5-T1
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What does the basal plate of the neural tube develop into?
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Motor neurons
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What is bone morphogenic protein?
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Ectoderm overlying the neural secretes BMP to induce the alar plate to develop sensory neurons
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What seperates the basal and alar plates?
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sulcus limitans
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What is decorticate spinal posture?
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Posture indicative of damage close to the source of cortical input to posture (internal capsule). Upper limbs flexed and lower limbs extended.
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What is decerebrate posture?
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Posture indicative that input has been completely cut off from the cerebrum, all four limbs are extended
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What happens to reflexes when the spinal cord is cut of?
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Hyperflexia - all normal relexes become exaggerated and some new ones appear
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What is the Babinski sign?
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Stroking lateral sole causes big toe to pint up and toes to fan out. Corticalspinal damage
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What is Hoffman's sign?
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Flicking the terminal phalanx of the third or fourth digit causes flexion of the thumb
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What are the three divisions of white matter in the spinal cord?
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The posterior, lateral, and anterior funiculus
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What are funiculi divided into?
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Fasciculi or tracts
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What spinal level does this represent and why?
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Transverse section of the cervical enlargement. Note the large anterior horn and small posterior horn and lack of lateral horn
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What spinal level does this represent and why?
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Transverse section of the cervical enlargement. Note the large anterior horn and small posterior horn and lack of lateral horn
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What spinal level does this represent and why?
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Transverse section of the lumbar spinal cord. Not the large anterior and posterior horns and the large posterior funiculi
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What spinal level does this show and why?
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Transverse section of the sacral spinal cord. Not the huge anterior and posterior horns surrounded by the narrow white matter.
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What does the posterior horn mainly consist of?
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Interneurons whose processes remain in the cord and projecting neurons whose axons collect into ascending pathways
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What are the three prominent parts of the posterior horn?
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Substantia gelatinosa, posterior marginalis, and nucleus proprius
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What is substantia gelatinosa?
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Region of grey matter that stains pale because of finely myelinated and unmyelinated sensory fibers that carry pain and temperature info.
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What is Lissaur's tract?
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Pale staining area of white matter associated with the gelatinosa.
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How do pain afferents synapse?
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They enter laterally and synapse almost immediately. Lissauer's tract carries these migrating axons but only for a short time before they enter the dorsal horn and synapse.
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What is flaccid paralysis?
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Destruction of lower motor (alpha motor) neurons that causes limpness. No reflex action. Can be caused by polio or spinal injury
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What are fusimotor neurons?
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Gamma motor neurons tht innervate the intrafusal muscle fibers of muscle spindles.
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What is the pathophysiology of Parkinson's Disease?
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Substantia nigra deteriorates and can no longer produce dopamine
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Where do leg fibers synapse?
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Clarke's nucleus and then enter dorsal spinocerebellar tract
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What does the lateral horn contain?
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Preganglionic neurons of the sympathetic nervous system
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What is lamina I?
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Located at all levels and function for some of the spinothalamic tract. Thin layer of grey matter that covers the substantia nigra
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What is lamina II?
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Nucleus is the substantia gelatinosa at all levels. Used to modulate transmission of pain and temperature
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What are lamina III-IV?
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The body of the posterior horn and involved in sensory processing.
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What is Lamina VII?
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Intermediate grey matter including clarke's nucleus and large extension into anterior horn
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What are the three portions of Lamina VII?
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1 - posterior spinocerebellar tract cells with clark's nucleus 2 - preganglionic sympathetic neurons 3 - preganglionic parasympathetic neurons to the pelvic viscera
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What is lamina VIII?
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Comprises some of the interneuronal zones of the anterior horn
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What is lamina IX?
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A cluster of motor neurons embedded in the anterior horn
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What is the accessory nucleus?
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Medulla to C5 - motor neurons for SCM and trapezius
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What is the phrenic nucleus?
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C3-C5 are the motor neurons to the diaphragm
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What is lamina X?
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Zone of grey matter surrounding the central canal
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What are the pain and temperature efferents?
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Lamina I and II
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What are the tactile afferents from cutaneous nerves?
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Lamina III
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What lamina contain I alpha spindle afferents?
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VI, VII
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What is the knee jerk reflex?
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Myotatic, 2 neuron loop. Afferent from muscle spindle detects stretch and causes efferent to fire and muscle twitch
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Why is the muscle spindle called intrafusal?
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the sheath has a spindle of fusiform shape
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Why are Ialpha fiber classified as such?
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Classified based on diameter, so Ialpha are largest and fastest. Fire frequently as muscle stretches
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What does the second stretch fiber of the muscle spindle do?
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It adapts slower than the Ialpha fiber and continues firing after the muscle has stopped stretching, allos for proprioception
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What are Ibeta fibers?
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Golgi tendon, monitor tension
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How does clonus occur?
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Pyramidal tract damage and the golgi and stretch relfex get caught in a loop. Can also be a sign of fatigue
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What do the ascending axons of the nuclei grcilis and cuneatus do?
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They arch ventro medially as internal arcuate fibers and form the opposite medial lemniscus dorsal to the pyramids
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What do the spinothalamic and spinotectal tracts become as they ascend into the medulla?
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Spinal lemniscus
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What does the central canal continue into?
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The fourth ventricle
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What do the corticospinal fibers do as they ascend to the medulla?
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They form the pyramids that cross at the pyramidal decussation to form the lateral corticospinal tract in the lateral funiculus of the cord
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Where is substantia nigra located?
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In the midbrain
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How is the midbrain divided?
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left and right cerebral peduncles, each consisting of a ventral crus cerebri, dorsal tegmentum and intervening substantia nigra
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Where do the two occulomotor nerves arise from?
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The interpenduncular fossa of the crus cerebri in the mid brain
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What are the three functions of the midbrain?
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conduit, cranial nerve, and integrative functions
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What is the head's equivalent of lissauer's tract?
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the trigeminal nerve
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What is the site of the cuneatus nucleus?
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The cuneate tubercle
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What three cranial nerves enter/exit along the groove between the basal pons and medulla?
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Abducens VI, facial nerve VII, and vestibulocochlear
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Where does the occulomotor nerve emerge from?
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The interpeduncular fossa of the midbrain
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What does the surface of the cerebral hemisphere consist of?
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archicortex (hippocampal formation); paleocortex (olfactory and some limbic areas); and neocortex (has 6 layers)
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In which layers are the principal (pyramidal) cells most conspicuous?
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layers 3 and 5
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Where are the six layers of the cortex most distinct?
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association areas
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In primary sensory areas, where are stellate cells most prominent?
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layer 4
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What afferents excite pyramidal cells?
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corticocortical, thalamocortical, cholinergic, peptidergic
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What are mini-columns?
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vertical strings of neurons that compose the cortex. they can be grouped into larger columns or modules; and each module responds only to a specific type of signal.
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What does maturation of columnar organization require?
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exposure to sensory experiences early in postnatal life.
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What are principal cells?
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big corticospinal neurons that are main projection neurons; principle output cells of cerebral cortex
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What can result from damage to Wernicke's area?
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aphasia and agnosia
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Which is the most rotral part of the brain?
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telencephalon
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What does the telencephalon cosist of?
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cerebral cortex (gray matter), core of white matter (beneath gray matter), basal ganglia (gray matter embedded in white matter core)
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Which side of the body does the right cerebral hemisphere control?
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left side
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What are the massive bands of white matter that join the cerebral hemispheres called?
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corpus callosum and anterior commissure
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What does the corpus callosum connect?
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everything but the inferior and middle temporal lobes
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What does the anterior commissure connect?
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inferior and middle temporal lobes
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What is the function of the insula?
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associated with visceral functions and integrates autonomic information
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Where is the insula located?
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within the cerebral cortex, beneath the frontal, parietal, and temporal opercula; it overlies the site where the telencephalon and diencephalon fused during embryological development
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What is the insula involved with?
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the intermediate or lateral sulci and parasympathetic cranial nerves
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What is the function of the fornix?
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it connects the hypothalamus to the cerebrum
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What is the location of the fornix?
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fibrous tract that extends from the hippocampus to the mamillary body of the hypothalamus and forms an arch over the thalamus
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What is function of the frontal lobe?
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determines intelligence, determines personality, interpretation of sensory impulses, motor function, planning and organization, touch sensation
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Where is the frontal lobe located?
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in the anterior portion of the forebrain and divided into two hemispheres that are connected by the corpus callosum
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What is the function of the temporal lobes?
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emotional responses, hearing, memory, speech
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What is the location of the temporal lobes?
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anterior to the occipital lobes and lateral to the Fissure of Sylvius
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What is the function of the parietal lobes?
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cognition, information processing, pain and touch sensation, spatial orientation, speech, visual perception
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Where is the parietal lobe located?
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anterior to the occipital lobes and posterior to the central sulcus (fissure) and frontal lobes
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What is the function of the occipital lobe?
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controls vision, color recognition
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What is the location of the occipital lobes?
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most caudal portion of the cerebral cortex
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What is the cerebral cortex?
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a sheet of neurons and their interconnections that plates the corrugated surface of the cerebral hemispheres in a layer that is only a few mm thick. This think layer of gray matter is estimated to contain 30 billion neurons
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What is the histology neocortex?
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more than 90% of our total cortical area; has 6 layers for a structure; often referred to as the homogenetic cortex
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What is the histology of the paleocortex?
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covers some restricted parts of the base of the telencephalon (olfactory areas); referred to as heterogenic cortex (along with archicortex); has 3 layer strucutre
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What is the histology of the archicortex?
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hippocampal formation; referred to as heterogenic cortex (along with paleocortex); contains 4 layers
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What are the cortex cell types?
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stellate (granule) cells, pyramidal cells, horizontal cells (of Cajal), fusiform cells, Cells of Martinotti
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Where are Cells of Martinotti found?
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in all cortical layers but are abundant in deeper layers (layers 5 and 6)
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What are Cells of Martinotti?
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small, multipolar neurons with short well developed dendrites, located in all layers and send axons up to cortical layer 1 to make contact w/ the pyramidal cells, and may be involved with cortical dampening
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Where are fusiform cells found?
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in the deepest cortical layer (layers 5 and 6)
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What are fusiform cells?
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spindle shaped with a tuft of dendrites emerging from each end of the spindle and have axons that leave the cortex (like pyramidal cells)
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What are the output cells of the cerebral cortex?
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fusiform and pyramidal cells
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Where are horizontal cells (of Cajal) located?
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within the most superficial cortical layer (extending their receptive dendrites laterally on the surface of the first layer)
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What is the primary function of horizontal cells (of Cajal)?
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provide linkages to distant cells and correlation
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When are horizontal cells (of Cajal) most prominent and what are the used for?
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prominent during development but disappear after birth; probably used to develop association connection and provide sustentacular support
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What are stellate (granular) cells?
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typically small multipolar neurons with short axons that do not leave the cortex; are the principle interneurons of the neocortex and are mostly in sensory and association areas of the neocortex
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|
|
What are pyramidal cells?
|
range in size from 10µm in diameter to 70-100µm (large cells in the motor cortex are called Betz cells); have long apical dendrite that leaves the top of each pyramidal cell and ascends vertically to the cortical surface; a series of basal dendrites emerges from nearer the base of the cell and spreads out horizontally
|
|
|
Where are stellate cells seen?
|
in the postcentral gyrus; in layer 4
|
|
|
What are the apical dendrites of the pyramidal cells studded with?
|
dendritic spines (numerous small projections that are preferential sites of synaptic contact)
|
|
|
What is the difference between fusiform and pyramidal cells?
|
fusiform cells stay in the telencephalon (CNS) while pyramidal cells have long axons that leave the cortex to reach either the other cortical areas or to various subcortical sites
|
|
|
What are the cortical layers?
|
molecular layer, external granular layer, external pyramidal layer, internal granular layer, internal pyramidal layer, multiform (polymorphic layer)
|
|
|
What is the molecular (plexiform) layer?
|
dendrites and axons of cortical neurons making synapses; neuroglia and rare horizontal cells
|
|
|
what is the outer granular layer?
|
dense population of small pyramidal cells and stellate cells [small neurons]; various axons and dendritic connections
|
|
|
What is the outer pyramidal layer?
|
moderate size; increasing size deeper
|
|
|
What is the inner granular layer?
|
densely packed stellate cells
|
|
|
What is the ganglionic or inner pyramidal layer?
|
large pyramidal cells (including Betz cells) and smaller numbers od stellate cells and small neurons
|
|
|
What is the multiform (fusiform) cell layer?
|
numerous small neurons, small pyramidal cells, stellate cells, especially superficially and fusifomr cells in deeper part
|
|
|
Are stellate cells present in agranular layers?
|
yes, but they are overpowered by pyramidal cells
|
|
|
the most superficial layer is the cell poor molecular layer and in early infant is made up of what type of cells?
|
horizontal cells
|
|
|
The deepest layer is the multiform layer which is largely populate by what cells?
|
fusiform cells
|
|
|
What type of cells do layers 2-5 mostly contain?
|
Stellate or pyramidal cells
|
|
|
What cells dominate layers 2 to 5 in the motor cortex?
|
large pyramidal cells
|
|
|
An apparent lack of Stellate cells cause the cortex to be known as what?
|
agranular
|
|
|
The primary sensory cortex projects mainly to what?
|
cortical regions (therefore do no give rise to many long axons)
|
|
|
In the primary sensory cortex, what type of cells dominate layers II-V?
|
small Stellate cells and pyramidal cells
|
|
|
What type of cortex is the primary sensory cortex?
|
grnaular cortex
|
|
|
What is the homotypical cortex?
|
an intermediate type of cortex in which the 6 layered structure can be seen
|
|
|
What are the afferent from other cortical sites that may arise in the same hemisphere?
|
association fibers
|
|
|
What are the afferent from other cortical sites that may arise in the contralateral hemisphere?
|
commissural fibers
|
|
|
Where are association nuclei located?
|
layer 1; these nuceli receive their inputs from a variety of places and project to fairly broad areas of association cortex
|
|
|
What are the 2 key areas of association cortex?
|
prefrontal cortex and parietal-occipital-temporal association cortex
|
|
|
What are the 2 large association nuclei in the thalamus that corespond to the association cortices?
|
dorsomedial nucleus and pulvinar/LP complex
|
|
|
The dorsomedial nucleus is reciprically interconnected with what?
|
prefrontal cortex and is involved with prefrontal function such as affect and foresight
|
|
|
Bilateral damage to dorsomedial nucleus has similar effects as?
|
a prefrontal lobotomy
|
|
|
Where do corticocortial fibers occur?
|
between homologous areas of two hemispheres
|
|
|
What are the two major bundles of corticocortical fibers?
|
commissural fibers (connecting left and right) and association fibers
|
|
|
where do the commissural fibers arise?
|
from pyramidal cells chiefly in layers II and III
|
|
|
where do most efferent fibers to the cortex of the contralateral hemisphere pass through?
|
corpus callosum
|
|
|
Where do efferent fibers interconnecting parts of the temporal lobes traverse?
|
anterior commissure
|
|
|
Which layer is the main subcortical output layer?
|
layer V
|
|
|
What are association fibers?
|
longer efferents to ipsilateral cortical areas (to different lobes on the same hemisphere)
|
|
|
What is the corpus callosum?
|
largest fiber bundle in the human brain (containing more than 300 million axons)
|
|
|
What are the four subdivisions of the corpus callosum?
|
rostrum (forming part of the forceps minor), genu (forming part of the forceps minor), trunk, splenium (forming part of the forceps major)
|
|
|
What do the rostrum and genu interconnect?
|
the anterior part of the frontal lobe
|
|
|
What does the trunk interconnect?
|
the posterio part of the frontal lobe and the entire parietal lobe and the superior part of the temporal lobe
|
|
|
what does the splenium interconnect?
|
the occipital lobes
|
|
|
Nearly all cortical areas receive commisural areas. what are the few exceptions?
|
hand area of the somatosensory cortex; all of area 17 (occipital area) not representing areas adjecent to the vertical midline
|
|
|
What is the anterior commissure?
|
commissural fibers to and from the temporal lobe (inferior and middle) pass through this, especially those of the middle and inferior temporal gyri
|
|
|
What are the most prominent bundles of association fibers?
|
superior longitunidal fasciculus, superior occipitofrontal fasciculus, inferior occipitofrontal fasciculus, cingulum
|
|
|
what does the superior longitudinal fasciculus consist of?
|
a long pair of bidirectional bundles of neurons that connect the front and back of the cerebrum
|
|
|
What does the superior longitudinal fasciculus connect?
|
connects frontal, occipital, parietal, and temporal lobes (fibers to temporal lobe travel around the putamen)
|
|
|
Which corticocortical fibers are discrete and which are not?
|
association fibers are NOT discrete while commisural fibers are
|
|
|
What is another name for the superior longitudinal fasciculus?
|
arcuate fasciculus that sweeps along in a great arc above the insule
|
|
|
What is the superior occipitofrontal fasciculus (subcallosal bundle)?
|
it runs between the frontal and occipital lobes and perpendicular to the corpus callosum and the caudate nucleus
|
|
|
What is the inferior occipitofrontal fasciculus?
|
passes below the insula and runs from the frontal lobe and passes through the temporal lobe and back to the occipital lobe with its fibers fanning out at both ends of the fasciculus
|
|
|
What is the uncinate fasciculus?
|
the fibers that hook around the lateral sulcus to interconnect the orbital cortex and the anterior temporal cortex
|
|
|
What is the cingulum?
|
a collection of white matter fibers that project from the cingulate gyrus to the entorhinal cortex allowing for the communication between components of the limbic system. it also continues around the parahippocampal gyrus to nearly complete a circle and is part of the limbic lobe (behavior)
|
|
|
What is the entorhinal cortex?
|
a memory center and the main input to the hippocampus
|
|
|
What is the location of Brodmann area 4?
|
precentral gyrus, paracentral lobe (also called primary motor area)
|
|
|
What is the location of Brodmann area 6?
|
superior and middle frontal gyri, precentral gyrus (also called premotor area, supplementary motor area)
|
|
|
What is the location of Brodmann area 8?
|
superior and middle frontal gyri (also called inferior portion=frontal eye filed)
|
|
|
What is the location of Brodmann area 44, 45?
|
opercular and triangular parts of inferior frontal gyrus (aka Broca's area)
|
|
|
What is the parts triangular (of the inferior frontal gyrus)?
|
broadmann area 44 and 45, located on the lateral surface of the frontal cortex, inferior to BA9 an adjacent to BA46; occupying the triangular part of the interior frontal gyrus and surrounding the anterior horizontal limb of the lateral sulcus
|
|
|
Where is braodmann area 17 located?
|
bank of the calcarine sulcus in the occipital lobe (aka primary visual cortex V1)
|
|
|
Where are Brodmann areas 18, 19 located?
|
surrounding BA 17 (aka visual association areas V2, V3, V4, V5)
|
|
|
What brodmann area is auditory?
|
superior temporal gyrus 41(primary auditory area A1) , 42(auditory association area (A2)
|
|
|
What brodmann area is wernicke?
|
22 (superior temporal gyrus)
|
|
|
What is the neocortex of each hemisphere traditionally divided into?
|
primary sensory area (receives inputs from the thalamic relay nuclei); primary motor cortex (giving rise to pyramidal tract); association areas; limbic areas
|
|
|
The association cortex is commonly divided into what two types?
|
adjacent to a primary area or unimodal association area; multimodal or heteromodal association areas
|
|
|
What is the purpose of the unimodal association area?
|
devoted to an elaboration of the business of that primary area
|
|
|
What is the purpose of the multimodal area?
|
neurons in these areas typically respond to multiple sensory modalities and may change their response porperties under different circumstances (these areas are concerned with high level intellectual functions)
|
|
|
What do the multimodal association areas include?
|
inferior parietal lobule and large portions of the frontal and temporal lobes
|
|
|
What receptors are Area 3 involved?
|
slowly adapting cutaneous receptors (Ruffini nerve endings)
|
|
|
Area 1 is involved with what type of receptors?
|
rapidly adapting cutaneous receptors (Pacinian corpsucle receptors)
|
|
|
Area 2 is involved with what receptors?
|
deep receptors of the joints
|
|
|
Brodmann area (3, 1 2) is often referred to as what?
|
the first somatosensory area S1
|
|
|
What does the second somatosensory area?
|
S2 that occupies the parietal operculum and much of it is buried in the lateral sulcus
|
|
|
What does brodmann area 41 (primary auditory cortex A1) receive?
|
most of the auditory radiation from the medial geniculate nucleus via the sublenticular part of the internal capsule
|
|
|
What does Brodmann are 42 receive ?
|
auditory information from both area 41 and the medial geniculate nucleus
|
|
|
What is Broadmann area 22?
|
forms much of the superior temporal gyrus and is called the auditory association cortex
|
|
|
What is Brodmann area 4?
|
primary motor cortex (precentral gyrus); discrete contralateral movements of one muscle or small groups of muscles. Movements of the palate, pharynx, masseter, and often the tongue (but not the face) are bilateral
|
|
|
What is Brodmann area 6?
|
premotor area that is anterior to the precentral gyrus; movements are slower and involve larger groups of muscles
|
|
|
What is the supplementary motor area- area 6?
|
on the medial surface of the hemisphere, anterior to the representation of the foot in the primary motor cortex. It causes movements that are assumption of postures and may involve muscles on sides of the body.
|
|
|
Is language lateralized in the human brain?
|
yes
|
|
|
Which is the dominant hemisphere?
|
the hemisphere that is more important for the comprehension and production of language
|
|
|
Broca's areas is considered to contain what?
|
motor programs for the generation of language
|
|
|
What is Broca's apahsia called?
|
non-fluent, motor, or expressive aphasia
|
|
|
What is Wernicke's area considered to contain?
|
the mechanisms for the formation of language
|
|
|
What is Wernicke's aphasia?
|
a lesion in Wenricke's area in which the person is able to produce written and spoken words but the words or sequence in which they are used are defective in their linguistic content
|
|
|
what is Wernicke's aphasia called?
|
fluent, sensory, or receptive aphasia
|
|
|
What are the consequences of large lesions of right parietal lobe?
|
Difficulty with spatial orientation to everything on the left side; The patient may completely ignore the halves of objects to the left side as well as on the left side of the body; In some case , there is a general difficulty in spatial orientation that shows up as a difficulty in following maps or in finding locations even in familiar surroundings.
|
|
|
What are the consequence of large lesions of the left parietal lobe?
|
There is sometimes contralateral neglect, but much less frequently; The lesion my encroach on Wernicke’s area and cause more prominent aphasic disturbances
|
|
|
What are symptoms of prefrontal cortex lesion?
|
The patient becomes carefree and apparently euphoric; There is a loss in their capacity to do things for a delayed reward – democrats; They are less inclined to observe social norms – republicans; They have a lowered level of concentration, attention span, initiative, spontaneity and abstract reasoning
|
|
|
What is light touch?
|
awareness and precise location of mechanical stimuli
|
|
|
What is the ability to recognize objects from touch alone using size; shape; texture weight?
|
stereognosis
|
|
|
What is the ability to recognize numbers or letters drawn on the skin?
|
graphesthesia
|
|
|
What do graphesthesia and stereognosis require?
|
the dorsal columns and the memory of the object being articulated
|
|
|
What is high frequency vibration and what is it associated with?
|
256 Hz involves subcutaneous connective tissue, periosteum, and muscle. Associated with proprioception
|
|
|
What is low frequency vibration and what is it associated with?
|
128 Hz is fine vibration on the skin and are often associated with light touch
|
|
|
What is Romberg sign?
|
indicated the absence of position sense because the patient cannot stand with the eyes closed
|
|
|
What is fast pain and what carries it?
|
sharp, prickling and well localized. carried by Adelta fibers (5-30 m/s)
|
|
|
What is slow pain and what carries it?
|
dull, burning type and is diffuse rather than localized. Usually tissue injury. carried by C fibers (0.5-2m/s)
|
|
|
What are Meissner's corpuscles?
|
receptors that sit underneath the epidermis and are sensitive to light touch at 50 Hz range
|
|
|
What are rapidly adapting peripheral receptors?
|
they quickly stop firing in response to a constant stimulus (meissner's corpuscles and pacinian corpuscles)
|
|
|
what are slowly adapting peripheral receptors?
|
they do not stop firing (merkel's receptors and ruffini endings)
|
|
|
Although pain will result from damage to a free nerve ending in reality most pain is a result of substances released by damaged tissue.
|
prostaglandins, histamine, substane P; free nerve endings have receptors for these substances and lets you know when tissue has been damaged
|
|
|
What is the speed of Aalpha fibers and wat are they used for?
|
80-120 m/s for limb position and motion
|
|
|
What is the speed of Abeta fibers and wat are they used for?
|
35-75m/s for tactile pressure and vibration
|
|
|
What is the speed of Adelta fibers and wat are they used for?
|
5-35 m/s for fast pain, cold
|
|
|
What is the speed of C fibers and wat are they used for?
|
0.5-2.0 m/s for slow pain, warmth
|
|
|
Which axon fibers are unmyelinated?
|
C fibers
|
|
|
What is rexed lamina I?
|
posterior marginalis
|
|
|
What is rexed lamina III or IV?
|
nucleus proprius
|
|
|
What is the substantia gelatinosa filled with?
|
interneurons
|
|
|
What forms the walls and floor of the third verntricle?
|
thalamus, epithalamus, hypothalamus
|
|
|
What forms the floor of the lateral ventricle?
|
thalamus
|
|
|
What does the reticular nucleus do?
|
modulates the exchange of signals between other thalamic nuclei and the cerebral cortex
|
|
|
What do most thalamic nuclei receive?
|
subcortical afferents
|
|
|
How are the neurons in the thalamus connected with the cerebral cortex?
|
reciprocally connected
|
|
|
What do the ventral group of thalamic nuclei include and what are they involved with?
|
medial and lateral geniculate bodies, which are parts of the auditory and visual systems and somtosensory ventral posterior nucleus
|
|
|
Which thalamic nuclei are parts of pathways to motor areas of the cerebral cortex?
|
ventral lateral and ventral anterior
|
|
|
What is the importance of the intralaminar nuclei?
|
receives afferents from many sources, projects to the whole neocortex and the striatum, involved in awareness, arousal, and motors controls
|
|
|
Which is the largest thalamic nuclei?
|
pulvinar nucleus
|
|
|
Which thalamic nuclei are part of the limbic system?
|
anterior and lateral dorsal nuclei of the thalamus
|
|
|
What is the importance of the mediodorsal thalamic nucleus?
|
receives afferents from the amygdala, entorhinal area, spinal cord, and corpus striatum; it projects to the prefrontal cortex
|
|
|
What is the importance of the lateral posterior nucleus and the pulvinar nucleus?
|
receives input from the visual system and porjects to the cortex of the parietal and frontal lobes and the cingulate gyrus
|
|
|
What are the characteristics of the subthalamus?
|
contains various bundles of fibers connected with the thalamus, rostral parts of some midbrain nuclei, and the subthalamic nucleus
|
|
|
What is subthalamic nuclei connected with?
|
pallidum
|
|
|
What does a destructive lesion to the subthalamic nucleus result in?
|
contralateral hemiballismus (lurch forward)
|
|
|
What does the epithalamus consist of?
|
stria medullaris thalami, habenular nuclei, posterior commissure, pineal gland
|
|
|
Where do hypothalamic efferent fibers go and what do they control
|
go to brain stem and spinal cord for control of autonomic and other involuntary functions
|
|
|
What does the forebrain consist of?
|
diencephalon (interbrain) and paired cerebral hemispheres
|
|
|
the diencephalon contains functional centers for the integration of what?
|
all information passing from the brainstem and spinal cord to the cerebral hemispheres; motor and visceral activities
|
|
|
What do the two cerebral hemispheres integrate?
|
highest mental function such as awareness of sensations, emotions, learning and memory, intelligence and creativity, language
|
|
|
What cranial nerve feeds directly into the diencephalic area?
|
optic nerve (CN II)
|
|
|
What are the subdivisions of the diencephalon?
|
thalamus, hypothalamus, subthalamus, epithalamus
|
|
|
What does the diencephalon contain?
|
the third ventricle
|
|
|
What cranial nerve do the cerebral hemispheres receive?
|
olfactory (CN I)
|
|
|
What do the cerebral hemispheres contain?
|
lateral ventricles separated by the septum pellucidum
|
|
|
What does the thalamus decide?
|
which information is worthy of cognition
|
|
|
What is located in the thalamus in terms of somatosensory?
|
third order cells bodies for sensory
|
|
|
How does the cerebral cortex shut down processes?
|
it sends information down via reticular formation. Lateral branches coming off the reticular formation hit interneurons and shut down the process
|
|
|
What is the only part of the diencephalon that can be seen in the intact brain?
|
hypothalamus because fo the mamillary bodies and infundibular stalk
|
|
|
What forms the wall of the third ventricle?
|
medial surface of the diencephalon
|
|
|
What does the superior portion of the diencephalon border?
|
the body of the lateral ventricle and the subarachnoid space of the transverse cerebral fissure
|
|
|
What is the diencephalon exposed to inferiorly?
|
subarachnoid space
|
|
|
What laterally bounds the diencephalon?
|
internal capsule
|
|
|
What is the caudal boundary of the diencephalon?
|
plane through the posterior commissure and the caudal edge of the mammillary bodies
|
|
|
How does the pineal gland arise?
|
as an evagination from the roof of the diencephalon
|
|
|
What does the pineal gland consist of?
|
pinealocytes (secretory cells), glial cells, and a rich vascular supply
|
|
|
What is the pineal gland involved in?
|
regulation of some form of rhythm in the body
|
|
|
What can pineal gland tumors result in?
|
closure of cerebral aqueduct leading to hydrocephalus; defects of eye movements and pupilarry reactions b/c of damage to the oculomotor and trochlear nuclei and pathways that end at these nuclei; change in sexual function; changes in mood and depression
|
|
|
Nonparenchymal pineal tumors results in what?
|
destruction of pinealocytes and are associated with stopping of anti-gonadotropic substance production
|
|
|
Why is the pineal gland of clinical importance?
|
at about 17 years old, it calcifies to some degree and is useful as a landmark in x-rays
|
|
|
How is the pineal gland attached to the dorsal surface of the diencephalon?
|
by a stalk, caudally at the base of the stalk is the posterior commissure, rostrall is a swellin gon each side called the habenula
|
|
|
How are the two habenular nuclei interconnected?
|
habenular commissure
|
|
|
What is the major input buncle that the habenula receive?
|
stria medullaris of the thalamus which gives rise to the habenulointerpeduncular tract
|
|
|
What is the habenulointerpeduncular tract involved in?
|
involved in limbic structures and can influence the reticular formation
|
|
|
What do parts of the tegmetum continue into the diencephalon as?
|
subthalamus, area is completely surrounded by neural tissue and is located inferior to the thalamus, lateral to the hypothalamus and medial to the internal capsule
|
|
|
What does the subthalamus contain?
|
rostral portions of the red nucleus and substantia nigra and is traversed by somatosensory pathways on the way to the thalamus as well as several pathways involving the cerebellum and basal ganglia
|
|
|
What is the subthalamus involved in?
|
fine motor control and proprioception
|
|
|
describe the subthalamic nucleus.
|
lens shaped, biconvex structure located just medial and superior to portions of the internal capsule
|
|
|
What is interconnected with the subthalamic nucleus?
|
basal ganglia
|
|
|
What is the zona incerta?
|
a small mass of gray matter intervening between the subthalamic nucleus and the thalamus
|
|
|
Which is the only subdivision of the diencephalon on the ventral surface of the brain?
|
hypothalamus, located in the median part of the middle cranial fossa just above the diaphragma sella
|
|
|
What are the three main subdivisions of the hypothalamus in the anterior plane?
|
supraoptic (anterior part located dorsal to the optic chiasm); tuberal (located between the mamillary and supraoptic regions; contains infundibulum); mammillary (posterior, named owing to the relation to the mamillary bodies of the cerebral hemisphers which are small ball barring sized located in the rostral part of the interpeduncular fossa)
|
|
|
What are the thalami?
|
two egg shaped masses bordering the third ventricle and dorsal to the hypothalamic sulcus
|
|
|
What is the interthalamic adhesions (or massa intermedia)?
|
in most brains the right and left thalami are fused, partially, across the third ventricle
|
|
|
What is the location of the thalamus?
|
extends anteriorly to the interventricular foramen anterior tubercle; superiorly to the transverse cerebral fissure; and the floor of the lateral ventricle; inferior to the hypothalamic sulcus in the back it overlaps the midbrain
|
|
|
What is relayed in the thalamus?
|
all sensory pathway
|
|
|
anatomical circuits used by what also have relays in the thalamus?
|
cerebellum; basal ganglia; and limbic structure (these various systems utilize more or less separate portions of the thalamus, which has therefore been subdivided into a series of nuclei)
|
|
|
What is the anterior tubercle?
|
a swelling in the thalamus at the interventricular foramen
|
|
|
what is the medullary stria?
|
a bundle of fibers on the dorsal medial surface of the thalamus
|
|
|
Where is the pulvinar nucleus located?
|
to the posterior of the thalamus
|
|
|
What are the eight nuclear masses formed for the large number of nuclei in the thalamus?
|
anterior, medial dorsal, ventral nuclear mass, ventral posterior mass dorsal nuclear mass, pulvinar, centromedian, reticular nucleus
|
|
|
What is the internal medullary lamina?
|
a thin sheet of bundles of myelinated fibers that separates the thalamus into three major divisions: anterior, medial, lateral
|
|
|
What is the anterior division of the thalamus?
|
located at the anterior tubercle of the thalamus and consists of the anterior nucleus
|
|
|
What does the medial subdivision of the thalamus include?
|
larger medial dorsal nucleus and a thing nucleus called the midline nucleus (along the wall of the third ventricle)
|
|
|
The interthalamic adhesion is a bridge of what?
|
the midline nuclei
|
|
|
What is the lateral subdivision composed of?
|
ventral nuclear mass and dorsal nuclear mass
|
|
|
What are the subdivisions of the ventral nuclear mass?
|
ventral anterior, ventral lateral , ventral posterior (ventral posterolateral, ventral posteromedial)
|
|
|
What are the subdivisions of the dorsal nuclear mass?
|
lateral dorsal; lateral posterior; pulvinar
|
|
|
which thalamic nuclei are involved in motor control circuits that include the cerebellum and basal ganglia?
|
ventral anterior and ventral lateral
|
|
|
which thalamic nuclei are involved in sensory?
|
ventral posterior nuclei
|
|
|
The undersurface of the pulvinar has which nuclei?
|
metathalamic, lateral geniculate, medial geniculate
|
|
|
Which nuclei have interconnections to the tectum and are involved in coordinating head and eye movements to sound?
|
lateral and medial geniculate
|
|
|
Where is the centromedian located?
|
within the internal medullary lamina
|
|
|
Which nuclei are related to the medullary laminae?
|
lateral and medial geniculate (one of each on each side)
|
|
|
Where is the reticular nucleus?
|
lateral to the external medullary lamina; it's a thin nucleus forming the most lateral part of the nucleus
|
|
|
What are the intralaminar nuclei?
|
a group of cells enclosed by the internal medullary lamina which splits at other locations within the thalamus
|
|
|
What are the largest of the intralaminar nuclei?
|
centromedia and parafascicular nuclei
|
|
|
What is the centromedian nucleus?
|
a large, rounded nucleus located medial to the VPL/VPM complex; in which the VPM conforms to the rounded shape of the CM (CM is dense collection of cell bodies that cannot be condensed any further)
|
|
|
What is the parafascicular nucleus?
|
located medial to the centromedian nucleus and has the habenulointerpeduncular tract pass through it
|
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What is the second curved sheet of myelinated fibers that covers the lateral surface of the thalamus?
|
external medullary lamina
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|
What is the thalamic reticular nucleus?
|
thin shell of cell that intervenes between the external medullary lamina and the internal capsule
|
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|
What is the midline nuclei?
|
a rostral continuation of the parts of the periaqueductal gray matter and covers portions of the medial surface of the thalamus
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Where is the midline nuclei located?
|
ventricular surface of the thalamus at the third ventricle
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|
What is the posterior thalamus?
|
area that underlies the rostral part of the cerebral peduncles and the level includes part of the cerebral hemispheres; the corpus callosum; the lateral ventricles; and the caudate and lentiform nuclei
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All thalamic nuclei are a mixture of projection neurons (except the reticular nuclei) whose axons provide what?
|
output from the thalamus and small inhibitory interneurons that use GABA as the neurotransmitter
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|
What percentage fo projection neurons account for in most thalamic nuclei?
|
75%
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|
What are the two types of inputs into the thalamus?
|
specific and regulatory
|
|
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What are specific inputs?
|
neurons that convey information to a given thalamic nucleus may pass on the cerebral cortex and also to additional sites.
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|
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What are two tracts that are examples of specific inputs?
|
medial lemniscus to VPL; optic tract to lateral geniculate nucleus
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|
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What are regulatory inputs?
|
neurons that contribute to decisions about whether and in what form information leaves the thalamic nucleus
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Where do most regulator inputs come from?
|
cortical area to which a given thalamic nucleus projects; thalamic reticular nucleus; diffure cholinergic, noradrenergic, and serotonergic endings from the brainstem reticular formation
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Which input exists in the greatest number in thalamic nuclei?
|
regulatory inputs
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|
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What is an example of a projection input?
|
The lateral geniculate nucleus is a good example of this. 10% of the synapses on projection neurons come from optic tract fibers and half or more come from the visual cortex (projection inputs)
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Distinctive patterns of outputs and specific inputs allow thalamic nuclei to be grouped into what 3 categories?
|
relay nuclei, assoication nuclei, intralaminar and midline nuclei
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What are relay nuclei?
|
receive a well defined bundle of specific input fibers and project to the particular area of the cerbral cortex; role is to deliver information from particular functional system to appropriate cortical areas
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What are association nuclei?
|
project to areas defined as association areas of the cortex but they have characterized patterns of inputs as well; they receive major contingents of specific inputs from the cerebral cortex itself and some from a variety of subcortical structures; thought to be important in distributino and gating of informaiton between cortical areas
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What are the roles of intralminar and midline nuclei?
|
involved in the function of basal ganglia and limbic systems; their specific inputs come from a wide array of sites prominently from the basal ganglia and the limbic system; they project not only areas of the cerebral cortex but even more prominently to parts of the basal ganglia and limbic systems
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|
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What are the two physiological states of projection neurons?
|
tonic mode and burst mode
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What determines the functional mode of a thalamic projection neuron at any given moment?
|
its regulatory inputs
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What is the mode of projection neurons during sleep?
|
during sleep projection neurons are in the burst mode dominated by rhythmic waves of depolarization and are effectively unable to transmit information about their specific inputs.
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|
|
What are the two areas of association in the cortex of in the human brain?
|
prefrontal cortex; parietal occipital temporal association cortex (which occupies the area surrounded by the primary somatosensory, visual, and auditory cortices) - each of these areas have a specific nuclei or nuclear complex associated with it
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What is the interconnection with the prefrontal cortex and is involved in prefrontal functions such as affect and foresight?
|
dorsomedial nucleus
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What are the results of bilateral damage to the dorsomedial nucleus or conections to the forebrain?
|
lose ability to have projected thought or advanced thoughts
|
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|
Major inputs from the dorsal medial nucleus also come from various elements of what system?
|
limbic system (amygdala)
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|
The parietal occipital temporal association cortex involves what?
|
pulvinar/lateral posterior complex of interconnection with the parietal, occipital, and temportal lobes.
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What is the major inputs to the parietal occipital temporal association cortex?
|
visual system
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|
Which thalamic nucleus has no projection to the cerebral cortex?
|
thalamic reticular nucleus
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|
What are the reticular nuclei?
|
a sheet of neurons that receive inputs from the cortex and from thalamic projection neurons and send inhibitory (GABA) projections back to he thalamus. It also receives input from fibers near giving off collaterals such as the VPL/ VPM nuclei complex.
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|
What is the internal capsule?
|
a compact bundle of fibers in the cleft between the lenticular nucleus (laterally) and the thalamus and the head of the caudate nucleus medial
|
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|
What travels through the internal capsule?
|
almost all neural traffic to and from the cerebral cortex
|
|
|
What are the 5 parts of the internal capsule?
|
anterior limb, posterior limb, genu, retrolenticular part, sublenticular part
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|
|
Where is stroke usually in the internal capsule?
|
posterior limb
|
|
|
What does the anterior limb of the internal capsule contain?
|
contains the fibers interconnecting that anterior nucleus and the cingulate gyrus and most of those interconnecting the dorsomedial nucleus and prefrontal cortex. Also included in this are the fibers (some) from the frontal lobe to the ipsilateral pontine nuclei (frontopontine fibers)
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What does the posterior limb of the internal capsule contain?
|
contains fibers interconnecting the VA and VL with the motor and premotor cortex. It also contains corticospinal and corticobulbar fibers and somatosensory fibers projecting from the VPL /VPM to the post central gyrus.
|
|
|
What does the genu of the internal capsule contain?
|
a transitional zone between the anterior and posterior limbs and contains some frontopontine fibers and many of the interconnecting VA and VL fiber with the motor and premotor cortex. Corticobulbar fibers to motor nuclei of cranial nerves are also located anterior to the corticospinal fibers in the genu.
|
|
|
What does the retrolenticular part of the internal capsule contain?
|
contains most of the fibers interconnecting the thalamus with the posterior portions of the cerebral hemispheres. This includes fibers in both directions to the parietal occipital temporal association complex and the pulvinar / LP complex. There is also a optic radiation which is a large collection of visual system fibers projection from the lateral geniculate nucleus to the calcarine sulcus
|
|
|
What does the sublenticular part of the internal capsule contain?
|
continuous with the retrolenticular part and contains the remainders of the optic radiation. This part also contains the auditory radiation whose fibers pass laterally from the medial geniculate nucleus under the lenticular nucleus and lateral sulcus and then turn superiorly to end in the transverse temporal gyri.
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|
|
What type of functions do cranial nerves have?
|
motor, parasympathetic, sensory
|
|
|
Which cranial nerves supply the extraoccular muscles of eyes?
|
II, IV, VI
|
|
|
Where are the nuclei involved in vertical eye movements located?
|
rostral midbrain
|
|
|
The trigeminal nucleus supplies masticatory and a few other muscles through what?
|
mandibular division of CN V
|
|
|
What does the facial motor nucleus supply?
|
facial muscles and stapedius
|
|
|
CN II contains preganglionic fibers from what?
|
Edinger-Westphal nucleus
|
|
|
Where do the preganglionic fibers of the ED nucleus end?
|
ciliary ganglion, which supplies the sphincter pupillae and ciliary smooth muscles
|
|
|
What supplies the salivary and lacrimal glands?
|
parasympathetic ganglia that receive preganglionic innervation from CN VII and IX
|
|
|
Where do all general somatic sensory fibers from cranial nerve ganglia (V and IX and some from VII and X) end?
|
trigeminal nuclei
|
|
|
What cranial nerves are special senses?
|
I, II, VIII
|
|
|
What cranial nerves are involved in taste fibers and what is their tract?
|
VII, IX, and some from X go in the solitary tract to the rostral end of the solitary nucleus
|
|
|
Which system are the cranial nerves components of?
|
peripheral nervous system that originates in thr brain and upper cervical spinal cord
|
|
|
Why are they called cranial nerves?
|
they exit the CNS through the cranium rather than the vertebral column
|
|
|
Where do cranial nerves (with the exception of I and II) originate?
|
brainstem
|
|
|
Where are the motor and sensory nuclei of cranial nerves located?
|
motor in medial brainstem, sensory in lateral brainstem
|
|
|
Basal refers to what and alar refers to what?
|
basal = motor, alar = sensory
|
|
|
Are sensory receptor cell bodies located in the nucleus itself?
|
not, they will always be located just outside the CN in a ganglion
|
|
|
What type of nerves are CN III, IV, and VI?
|
purely motor
|
|
|
Which muscles does CN III supply?
|
superior rectus, inferior rectus, medial rectus, inferior oblique
|
|
|
What happens to the eye if there is a CN III lesion?
|
eye is pulled down and out
|
|
|
Where is the CN III nucleus located and where does CN III exit?
|
nucleus located medially in midbrain, nerve exits in interpeduncular fossa
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|
|
Where is the EW nucleus in relation to the occulomotor nucleus?
|
medial and posterior to occulomotor nucleus
|
|
|
What happens when the EW nucleus is damaged?
|
pupil cannot constrict or accomodate light as well
|
|
|
How do eye drops from the ophthamologist inhibit the parasympathetic system causing pupil dilation?
|
acetylcholine antagonist (blocker)
|
|
|
What muscle does CN IV supply?
|
superior oblique
|
|
|
Why is the trochlear nerve unique?
|
it exits the brainstem dorsally and it crosses on its way out
|
|
|
Which eye does the left trochlear nerve nucleus supply?
|
right eye
|
|
|
what does the medial longitudinal fasciculus carry?
|
fibers from the trochlear down to other parts that control neck movement and coordinate other things
|
|
|
What muscle does CN VI supply?
|
lateral rectus
|
|
|
Where is the abducens nucleus located?
|
pons
|
|
|
What is the key landmark for finding the abducens nucleus?
|
facial colliculus, where facial nerve wraps around abducens nucleus
|
|
|
Where does CN VI exit?
|
pontomedullary junction
|
|
|
Which nerve covers all sensation from the face and mouth?
|
trigeminal nerve (V)
|
|
|
To what does the trigeminal nerve carry motor fibers?
|
muscles of mastication: medial pterygoid, lateral pterygoid, masseter, temporalis
|
|
|
Where is the mesencephalic nucleus of CN V located?
|
runs along the fourth ventricle and cerebral aqueduct just outside the periaqueductal gray
|
|
|
Where is the motor nucleus of CN V located?
|
midpons, landmark is streaking trigeminal nerve fibers through the middle cerebellar peduncle
|
|
|
Where is the main sensory nucleus of the trigeminal nerve located?
|
in the mid-pons lateral to the motor nucleus
|
|
|
Where is the spinal nucleus of CN V easiest to see?
|
caudal medulla
|
|
|
What does the spinal nucleus of V resemble in the spinal cord?
|
dorsal horn of spinal cord
|
|
|
What does the spinal tract of V resemble in the spinal cord?
|
Lissauer's tract
|
|
|
What does CN VII carry?
|
motor fibers to muscles of facial expression, sensation of taste, parasympathetic fibers to salivary glands
|
|
|
Where does CN VII exit?
|
mid-pontine, near pontomedullary junction
|
|
|
What carries taste of the anterior 2/3 of tongue?
|
facial nerve (VII)
|
|
|
What carries taste of palate and posterior 1/3 of tongue?
|
glossopharyngeal nerve (IX)
|
|
|
What is the pathway of taste?
|
taste fibers enter solitary tract of medulla and synapse in surrounding solitary nucleus
|
|
|
What does CN VIII carry?
|
auditory information from cochlea and vestibular information from semicircular canals, utricle, and saccule
|
|
|
Why is CN VIII clinically important?
|
acoustic neuroma (common type of tumor) can arise the the nerve as it exits the brainstem
|
|
|
Where are the cochlear and vestibular nuclei located?
|
cochlear = draped over inferiro cerebellar peduncles, vestibular = several subdivisions and extend throughout a large fraction of pons
|
|
|
Does CN IX have a nucleus?
|
no, it shares a nucleus with VII and X
|
|
|
Where does sensory motor information of IX go?
|
sensory foes to solitary nucleus (VII and X), motor comes from nucleus ambiguus (X)
|
|
|
What do parasympathetic fibers of IX innervate?
|
salivary glands
|
|
|
What nerves exit from the post-olivary sulcus?
|
IX, X, XI
|
|
|
Where are sweet, salty, bitter, and sour?
|
sweet and salty = anterior 2/3, bitter and sour = posterior 1/3 (gag reflex)
|
|
|
Where do the afferents of the inferior salivatory nuclei go?
|
jump in and go along with CN IX
|
|
|
What does the nucleus ambiguus innervate?
|
striated muscle throughout neck and thorax
|
|
|
What are indications of problems with the vagus?
|
hoarseness, deviation of uvula
|
|
|
Where is the nuclei of vagus located?
|
rostral medulla
|
|
|
What is the dorsal nucelus of vagus?
|
secretomotor parasympathetic nucleus (stimulates glands)
|
|
|
What does the solitary nucleus receive?
|
taste information, sensation from back of throat, visceral sensation (blood pressure receptors, blood-oxygen receptors, sensation in larynx and trachea, stretch receptors of gut)
|
|
|
Where does CN XII exit?
|
pre-olivary sulcus
|
|
|
What does CN XII innervate?
|
muscles of tongue
|
|
|
what indicates problems with XII?
|
tongue deviates to weak side
|
|
|
Where is the hypoglossal nucleus located?
|
midline throughout most of medulla
|
|
|
Where do the neurons of CN I enter the cranium?
|
cribriform plate of ethmoid bone and synapse in olfactory bulb of brain
|
|
|
What type of cell bodies are associated with CN I?
|
bipolar neurons
|
|
|
What is the term for loss of smell?
|
anosmia
|
|
|
What type of neurons does the optic nerve consist of?
|
tertiary sensory neurons arising in retina
|
|
|
Where does the optic nerve enter the cranium?
|
optic canal in the lesser wing of spehnoid bone
|
|
|
What type of tract is the optic nerve?
|
CNS tract rather than a true cranial nerve because retina and optic nerve develop from optic vesicle (an outgrowth of brain)
|
|
|
What nerves go through the superior orbital fissure?
|
III, IV, V1, VI
|
|
|
What does the superior division of the occulomotor complex supply?
|
lecator palpebrae superioris and superior rectus
|
|
|
What does the inferior division of the occulomotor complex supply?
|
medial rectus, inferior rectus, inferior oblique
|
|
|
In what direction does the superior oblique push eye?
|
down and in
|
|
|
What does damage to CN IV do?
|
eye goes up and out
|
|
|
Where does the trigeminal (V) exit?
|
lateral surface of the pons
|
|
|
What does the trigeminal ganglion correspond to in the spinal cord?
|
dorsal root ganglion of the spinal nerve
|
|
|
Where does V2 (maxillary nerve) exit the skill?
|
foramen rotundum into pterygopalatine fossa
|
|
|
What is the path of V2 after it enters the pterygopalatine fossa?
|
reenters infraorbital canal and exits through infraorbital foramen to innervate skin below eye and above mouth
|
|
|
Where does V3 exit the cranium?
|
foramen ovale
|
|
|
Why is V3 interesting?
|
some sensory neurons, specifically those conducting proprioceptive input from jaw muscles, have cell bodies located within the CNS rather than in the trigeminal ganglion
|
|
|
What is special about the mesencephalic nucleus?
|
it is the only place where pseudounipolar neurons exist in the CNS, the only cell bodies of PNS nerves located in CNS
|
|
|
What are the divisions of V1?
|
frontal, nasociliary, lacrimal
|
|
|
What does the lacrimal nerve act as a carrier for?
|
parasympathetics coming from CN VII
|
|
|
What are the divisions of V2?
|
infraorbital, posterior superior alveolar, palatine, nasopalatine
|
|
|
What is medial strabismus?
|
convergent squint caused by injury to abducens nerve
|
|
|
What is the branchial motor pathway of the facial nerve?
|
facial motor nucleus through internal acoustic meatus through stylomastoid foramen to muscles of facial expression
|
|
|
What does the geniculate ganglion contain?
|
cell bodies of general sensory neurons innervating the skin behing the ear as well as special sensory neurons innervating anterior 2/3 of the tongue
|
|
|
What are the branches of the facial nerve?
|
temporal, zygomatic, buccal, mandibular, cervical
|
|
|
Where do fibers of the superior and inferior salivatory nuclei go?
|
superior = lacrimal gland, inferior = sublingual and submandibular glands
|
|
|
What type of cell bodies are located in the spiral and vestibular ganglia?
|
bipolar neurons
|
|
|
What is the inferior ganglion associated with?
|
general sensation and taste from posterior 1/3 of tongue, visceral sensation, taste from epiglottis and back part of throat
|
|
|
where do cerebellar nuclei receive extra cerebellar afferents?
|
from the vestibular nuclei, reticular nuclei, pontine nuclei, and spinocerebellar tracts
|
|
|
what is the destination of the efferent fibers of the cerebelllar nuclei?
|
1-reticular and vestibular nuclei of medulla and pons 2-red nucleus of the midbrain 3-ventral lateral nucleus of the thalamus
|
|
|
Archicerebellum: lobe and nuclei
|
flocculonodular lobe and fastigial nuclei
|
|
|
Archicerebellum: function
|
maintanence with equilibrium (balance)
|
|
|
Archicerebellum: associated peduncle
|
connection with vestibular nuclei and reticular nuclei through inferior cerebellar peduncles
|
|
|
Archicerbellum: cortical efferent projections
|
project to fastigial nucleus → project back to vestibular nuclei and reticular formation. Mediated by vestibulospinal and reticulospinal projections
|
|
|
Paleocerebellum: function
|
influences muscle tone and posture
|
|
|
Paleocerebellum: associated tracts
|
dorsal and ventral spinocerebellar
|
|
|
Paleocerebellum: peduncles
|
inferior (dorsal) and superior (ventral)
|
|
|
Paleocerebellum: fiber termination
|
in the cortex of the ipsilateral vermis and paravermis
|
|
|
Paleocerebellum: nuclei
|
globose and emboliform
|
|
|
Paleocerebellum: interposed nuclei projections
|
project via the superior cerebellar peduncles to contralateral red nuceli where they influence cells giving rise to rubrospinal tract
|
|
|
Neocerebellum: function
|
muscular coordination, trajectory speed and force of movements
|
|
|
Neocerebellum: main fibers
|
pontocerebellar, terminate in lateral parts of the cerebellar hemispheres
|
|
|
Neorcerebellum: output
|
to dentate nucleus which projects to contralateral red nucleus and ventral latral nucleus of the thalamus
|
|
|
Neocerebellum: decussation of fibers
|
before reaching red nucleus, some pay pass the nucelus and go straight to the VL thalamus
|
|
|
How is extensive is the damage the higher up the lesion?
|
The higher up the lesion => the greater/more significant the symptoms
|
|
|
What type of innervation do the motor cranial nerves receive from the corticobulbar tract?
|
bilateral innervation, meaning that both the left and right pairs of CNs are innervated by motor strips of the right and left cerebral hemispheres
|
|
|
Will unilateral lesions of the corticobulbar tract strongly affect the CNs ability to receive information about voluntary motor movement from the cortex?
|
slightly, both sides will still be able to receive information but the message may not be as strong (paralysis will NOT occur)
|
|
|
What do bilateral lesions to the corticobulbar tract do?
|
cause serious, spastic dysarthira; pseudo-bulbar palsy will occur
|
|
|
What two CNs receive only contralateral innervation from the corticobulbar tract?
|
CN XII (part that controls tongue protrustion) and CN VII (part that innervates lower face) => these lesions do not affect speech
|
|
|
the extrapyramidal tract is involved in what kinds of movements?
|
gross movements, helps with posture and muscle tone, regulates reflexes, and facial expression
|
|
|
What are the components of the extrapyramidal tract?
|
basal ganglia, red nucleus, reticular formation and cerebellum (all these send information to lower motor neurons in an indirect, multi-synaptic fashion)
|
|
|
What is the function of the basal ganglion?
|
acts to inhibit the release phenomenon (rapid firing of motor neurons) and is aided by the substantia nigra of the midbrain => the head, hands, and fingers are most often affected
|
|
|
What NTs are involved in the inhibitory function of the basal ganglia?
|
dopamine (substantia nigra), acetylcholine, and GABA
|
|
|
What is the pathway of the rubrospinal tract?
|
the cerebellum sends information to spinal nerves: cerebellum -> superior cerebellar peduncles --> red nucleus --> spinal nerves
|
|
|
What type of information is sent through the rubrospinal tract?
|
information for somatic motor (skeletal muscle control) and regulation of muscle tone, smoothness of movement and for posture
|
|
|
What is the reticulospinal tract?
|
runs from the reticular nuclei of the pons and medulla to the spinal nerves; is involved in somatic motor and control of autonomic functions
|
|
|
What is the tectospinal tract?
|
point of origin is throughout the brainstem (especially in the midbrain) and ends in the spinal nerves; is involved in control of neck muscles and visual and auditory reflexes
|
|
|
What is the vestibulospinal tract?
|
runs from the vestribular nuclei located in the lower pons and medulla to the spinal nerves; is involved with balance
|
|
|
What is the pyramidal system involved with?
|
instigating, terminating, and altering movement
|
|
|
Where do the pyramidal tracts (corticospinal and corticobulbar) arise from?
|
motor areas and some from B3a of the neocortex
|
|
|
a lesion in the anterior corticospinal tract above the spinal segment where is synapses results in what?
|
contralateral motor loss of what is innervated because the fibers have not crossed yet
|
