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119 Cards in this Set
- Front
- Back
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Define "commissure"
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A group of nerve fibers that connect one side of the brain to the other
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Define "decussation"
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The actual crossing of nerve fibers from one side of the brain to the other
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What is a functional system?
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Neurons linked together to convey a particular type of information or task
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Differentiate "fissure" "meatus" "foramen" "fossa" and "groove/sulcus"
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Fissue - narrow cleftlike opening between adjacent parts of the brain through which blood vessels, nerves, or ligaments pass.
Meatus - canal - a tubelike passageway running within bone Foramen - an opening through which blood vessels, nerves, or ligaments pass Sulcus/groove - a ditchlike groove, a furrow or depression that accomodates a soft structure such as a blood vessel, nerve or tendon Fossa - basin-like depression, a depression in or on bone |
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Differentiate "cerebral cortex" and "subcortical matter"
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Cerebral cortex is the "gray matter" on the outer surface of the brain, containing cell bodies, forming folds, creases, and sensory/motor gyri/associations.
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Describe the path of the CSF in the ventricles.
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Lateral ventricles --> Interventricular foramen of Monro --> 3rd ventricle --> Cerebral Aqueduct of Sylvius --> 4th ventricule --> two lateral foramen of Luschka and one medial foramen of Majendie
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List the 12 cranial nerves (including the 3 parts of the trigeminal)
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CN I - Olfactory
CN II - Optic CN III - Oculomotor CN IV - Trochlear CN V - Trigeminal (V1 - Ophthalmic, V2 - Maxillary, V3 - Mandibular) CN VI - Abducens CN VII - Facial CN VIII - Vestibulocochlear CN IX - Glossopharyngeal CN X - Vagus CN XI - Accessory CN XII - Hypoglossal |
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What structure is impinged upon if the uncus herniates onto the tentorial notch (incisura)?
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Midbrain
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What structure is compressed when the cerebellar tonsil herniates against the foramen magnum?
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Medulla - affecting CV, respiration, reticular formation --> coma
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Where is the cerebello-medullary cistern (cisterna magnum)?
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Found below the cerebellum, infero-posterior to the 4th ventricle, above the medulla
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Where is the pontine cistern?
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Below and along the pons
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Where is the quadrigeminal cistern?
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Also known as the superior or cisterna ambiens - superior-anterior to the cerebellum, posterior to the superior and inferior colliculus
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Where is the interpeduncular cistern?
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superior to the pons, anteriorly
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Where is the choroid plexus found?
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Found at the arachnoid granulations in the ventricles (3)
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What is an arachnoid granulation?
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a bulge/granulation of arachnoid layer which protrudes into the superior sagittal sinus through the dura mater, CSF is eliminated.
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List the gyri of the frontal lobe.
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Prefrontal gyrus
Premotor cortex: Superior frontal gyrus, Middle frontal gyrus, Inferior frontal gyrus Gyrus rectus Orbital gyri |
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Which gyrus contains Broca's motor speech area?
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The inferior frontal gyrus
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List the gyri of the parietal lobe.
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Postcentral gyrus
Superior parietal lobule Inferior parietal lobule Supramarginal gyrus Angular gyrus |
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Where is Wernicke's area found?
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Inferior parietal lobule
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List the gyri of the temporal lobe.
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Superior temporal gyrus
Middle temporal gyrus Inferior temporal gyrus Heschl's gyrus - superior and medial to the superior temporal gyrus (primary auditory area) Occipitotemporal gyrus Parahippocampal gyrus |
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List the gyri of the occipital lobe.
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Cuneus gyrus
Lingual gyrus |
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What is the general role of the frontal lobe?
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Functions are motor and limbic.
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What is the general role of the parietal lobe?
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Receives and integrates sensory information
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What is the general role of the temporal lobe?
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Functions include auditory processing, deeper structures relate to memory and learning.
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What is the general role of the occipital lobe?
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Functions are mostly visual processing.
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What does the precentral gyrus do?
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Integrates motor functions - includes the primary motor cortex - controls voluntary movements. Somatotopically organized.
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What does the premotor cortex do?
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Includes the superior, middle and inferior gyri of the frontal lobe - the supplementary motor cortex. Initiates and sequences movements.
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What does the postcentral gyrus do?
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Receives somesthetic (tactile) information
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What do the superior and inferior parietal lobules do?
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Receives from audiovisual areas, discriminates and integrates information.
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What structure has to do with learning and memory? What lobe is it in?
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Hippocampus, within the temporal lobe.
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What gyrus is the primary auditory area?
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Heschl's gyrus
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What is the visual association gyrus?
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Precuneus gyrus
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What gyrus augments the precentral gyrus and postcentral gyrus?
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Paracentral gyrus - contains parts of the motor and sensory homunculus (mostly lower extremity)
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What lobe contains the cingulate gyrus?
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The 5th, the limbic lobe.
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What is regulated by the limbic system?
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Emotions, moods, behaviors, learning, visceral processes
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What is the role of the corpus callosum?
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It has huge bundles of axonal fibers, relays information between the brain hemispheres
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Name the four parts of the corpus callosum.
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Rostrum
Genu Body Splenium |
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Where are the olfactory bulb and tract located?
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Between the orbital gyri and gyrus rectus
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What is the rostral part of the parahippocampal gyrus?
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Uncus
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What are the four main parts of the diencephalon?
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Dorsal thalamus
Subthalamus (Ventral thalamus) Epithalamus Hypothalamus |
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What are the roles of the anterior and posterior commissures?
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Anterior - axonal fibers that relay information to and from the temporal lobes
Posterior - axonal fibers that are part of the visual system. |
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What is the Fornix?
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Axonal fibers that leave the hippocampus and project to the hypothalamus or septal areas.
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What is the septum pellucidum?
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Layer that separates the two ventricles
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What are the structures of the basal nuclei?
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Caudate nuclei
Putamen Globus pallidus Subthalamus Substantia nigra |
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What basal nuclei structures are in the corpus striatum?
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Caudate nuclei
Globus pallidus Putamen |
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What two basal nuclei structures compose the lentiform nucleus?
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Globus pallidus
Putamen |
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What are the three components of the brainstem?
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Midbrain
Pons Medulla Oblongata |
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What is the role of the brainstem?
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Relay information to and from the cortex via axons. Also contain nuclei involved in audio and visual processing, autonomic responses, and sensory/motor functions of the face
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What are some structures on the Midbrain (posterior, anterior)?
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Posterior - superior colliculus (visual), inferior colliculus (auditory).
Anterior - cerebral peduncles, tentorial notch |
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What are some structures on the Pons (posterior, anterior)?
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Anterior - bulges, relay information.
Posterior - superior, middle and inferior cerebellar peduncles. Superior medullary velum, facial colliculus, cerebellar pontine angle |
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What are some structures on the Medulla?
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Anterior - Pyramids, Olives
Posterior - Gracile tubercles, Cuneate tubercles |
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What is the role of the Cerebellum?
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Functions to coordinate and monitor motor activity
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Swelling of the infratentorial compartment affects what part of the CNS?
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Affects the brainstem and cerebellum
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What are the two major reflections of dura?
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Falx cerebri
Tentorium cerebelli |
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What is Chromatolysis?
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Damage to an axon provokes a series of morphological changes in the neuronal cell body, particularly disruption and dispersal of Nissl bodies, rearrangement of the cytoskeleton, accumulation of intermediate filaments, swelling.
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Describe Wallerian degeneration.
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A process that results when a nerve fiber is cut or crushed – in which part of the axon separated from the neuron’s cell nucleus degenerates. Aka anterograde degeneration. Macrophages and Schwann cells come by to clean up.
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Briefly describe the nerve-effect etiology behind Multiple Sclerosis.
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An autoimmune disease that attacks the myelin on axons and interferes with conduction of action potentials.
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Briefly describe the nerve-effect etiology behind Myasthenia Gravis.
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An autoimmune disease that affects the postsynaptic nicotinic acetylcholine receptors to inhibit binding at the sites.
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What is a Schwannoma?
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Peripheral nerve tumor originating from Schwann cells.
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In what part of the nervous system does Herpes Zoster stay dormant?
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Trigeminal ganglia and Posterior root ganglia
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Where does the myelin sheath originate in the CNS? PNS?
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CNS - Oligodendrocytes
PNS - Schwann cells |
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What are Nissl bodies?
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Rough endoplasmic reticulum
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What protein is used for retrograde transport? Anterograde?
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Anterograde transport - Kinesin
Retrograde transport - Dynein |
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What is an Astrocyte and what is its role?
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Also known as astroglia, Astrocytes are important cells which maintain the CNS neurons - supply nutrients, clean up apoptosis, maintain extracellular ion balance, participates in the repair and scarring process.
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What are Microglia and what is their role?
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Microglia are macrophages of the CNS - first line of defense against infection. 20% of total glial cells.
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What are Oligodendrocytes and what is their role?
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They are a variety of neural glia, which extends appendages and wraps around axons of nearby CNS cells - acts as a myelin sheath, and semi-organization.
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What is a fasciculus? What is its covering?
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A fasciculus is a nerve bundle - the protective sheath is "perineurium"
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What is Epineurium? Endoneurium?
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Epineurium - Outermost layer of connective tissue surrounding a PNS nerve - includes the blood vessels supplying the nerve. Consists of adipose tissue and fibrocollagenous tissue.
Endoneurium - a protective sheath of connective tissue that encloses the myelin sheath of a nerve fiber within a fasciculus |
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List 5 neurotransmitter substances.
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Acetylcholine
Noradrenaline Dopamine Serotonin GABA (gamma-amino-butyric-acid) |
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Describe the components of the anterior blood supply of the brain.
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Internal carotid artery --> anterior cerebral artery (1st branch: ophthalmic artery; 2nd branch: posterior communicating artery; 3rd branch: Callosomarginal artery; 4th branch: Pericallosal artery);
--> middle cerebral artery --> branches into M1, M2, M3, M4...; Lenticulostriate artery; |
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What structure is supplied by the pericallosal artery?
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Corpus callosum
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What region of the brain is served by the Middle Cerebral Artery?
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Lateral surface of the brain
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Describe the components of the posterior blood supply of the brain.
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Vertebral artery (branches that fuse become the anterior spinal artery); 2 posterior spinal arteries; 2 Posterior inferior cerebellar arteries; Fusion --> Basilar artery from which branch pairs (anterior inferior cerebellar arteries; superior cerebellar arteries; posterior cerebral arteries);
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What vessels contribute to the Circle of Willis?
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Anterior communicating artery
Anterior Cerebral Artery Internal carotid artery Posterior communicating artery Posterior cerebral artery Basilar artery |
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What is a watershed area?
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Border zone - areas where the major arteries terminate - there is an anterior border zone and a posterior border zone.
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Where is an anterior watershed infarct and what are some symptoms?
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Between anterior and middle cerebral arteries
Causes contralateral hemiparesis of the lower extremities, expressive language deficits, behavioral changes; |
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Where is a posterior watershed infarct and what are some symptoms?
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Between the posterior and middle cerebral arteries
Causes visual losses and some language problems. |
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What arteries supply the midbrain?
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Basilar artery
Superior cerebellar artery |
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What arteries supply the medulla?
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anterior spinal artery, vertebral artery, PICA, posterior spinal artery, AICA
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What arteries supply the pons?
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Basilar artery branches: long circumferential, short circumferential, paramedian
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Describe the route of superficial venous drainage from the brain.
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Superficial veins: superficial middle cerebral vein --> cavernous sinus; Superior anastamotic vein of Trolard --> superior sagittal sinus; Inferior anastamotic vein of Labbe --> transverse sinus;
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Describe the route of deep venous drainage from the brain.
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Deep veins - thalamostriate vein, internal cerebral veins, and great cerebral vein of Galen --> straight sinus --> confluence of sinuses; Inferior sagittal sinus and superior sagittal sinus --> straight sinus --> confluence of sinuses
Confluence of sinuses --> Transverse sinuses --> Sigmoid sinuses --> Internal Jugular Vein Cavernous sinus --> Inferior petrosal (--> IJV) and Superior petrosal (Sigmoid sinus --> IJV) |
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Describe the route of drainage from the brain starting with the cavernous sinus.
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Cavernous Sinus --> Superior and Inferior Petrosal Sinuses
Superior Petrosal Sinus --> Sigmoid Sinus Inferior Petrosal Sinus --> Internal Jugular Vein Transverse Sinus --> Sigmoid Sinus --> Internal Jugular Vein Confluence of sinus - receives from the Straight Sinus and Superior Sagittal Sinus, drains into the Transverse Sinus --> Sigmoid Sinus --> Internal Jugular Vein |
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What short branch of the straight sinus is more susceptible to injury?
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vein of Galen
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What cranial nerves would be affected by a rupture of the internal carotid arteries?
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CN III
CN IV CN V1 CN V2 CN VI |
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What is an aneurysm and where do they most often occur?
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Dilation of the vessel wall, tunica media
85% on internal carotid branches |
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What is a transient ischemic attack?
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Sudden loss of neurological function that resolves in a few minutes to a few hours - occurs when small emboli occlude small vessels.
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What is an arteriovenous malformation?
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When major arteries/veins do not develop normally, capillary bed is missing or abnormal
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What is an epidural hemorrhage and how would it appear radiographically?
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Extravasated blood strips dura from the skull, usually from injury to meningeal artery or vein - appears short and wide because blood doesn't cross through dura.
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What is a subdural hemorrhage and how would it appear radiographically?
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Occurs between the arachnoid and dura, results from the bridging veins tearing as they enter the superior sagittal sinus from a front or back blow, appears long and thin because it is running between dura and arachnoid layers.
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What is a subarachnoid hemorrhage and what kinds of symptoms would be produced?
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Bleeding beneath the meninges against the brain, symptoms include sudden onset of headache, stiff neck, loss of consciousness.
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What is a cerebral hemorrhage?
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Caused by hypertension often times, and often occurs at the lenticulostriate arteries - causes the "classic" stroke.
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Where do arteries tend to bleed in the meninges?
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Subarachnoid space
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Where do veins tend to bleed in the meninges?
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Extracranially, epidurally, subdurally.
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What may cause a peripheral nerve injury?
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Metabolic, collagen disease, malignancy, toxins, thermal or mechanical injury
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What are some causes of secondary injury to a nerve?
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Infection, scarring, callus, vascular complications
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What are the possible outcomes from damage to...
Soma Dendrites Axon |
Soma - cell will die
Dendrites - cell may die Axon - cell may die, or may recover (in which case it may have a different axon path) |
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What are the three stages of neuronal injury?
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Retraction
Inflammation Degeneration |
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What is occurring 2-3 days after distal degeneration of nerve fibers?
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Distal segments begin to fragment, Schwann cells close to the injury site are activated, there is de-differentiation, down-regulation of myelin genes, up-regulation of regeneration associated genes (RAG)
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What is occurring 3 days after distal damage to nerve fibers?
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Macrophages infiltrate distal nerve stump to remove majority of debris, takes about 1 month
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What is occurring 7 days after distal damage to nerve fibers?
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Schwann cells are mitosing, phagocytosing the debris.
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What is occurring 25-30 days after distal damage to nerve fibers?
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Axonal debris is cleared, bands of von Bungner may be present, guiding regeneration.
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What are bands of von Bungner?
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Schwann cells surround empty endoneural tubes to form bands of von Bungner, which guide and support axons to regenerate from the proximal nerve stump into and through the endoneural tubes of the distal nerve stump to promote regeneration.
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What is primary/retrograde/traumatic degeneration?
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Degeneration proximal to the point of detachment - only as far as the next node of Ranvier. Histologically the same as Wallerian degeneration.
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List three major change that occur with Chromatolysis.
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Dispersion of Nissl bodies (RER) to the outer side of the nuclear membrane and to the perimeter of the cytoplasm
Movement of the nucleus to an eccentric position within the cell body Swollen appearance |
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How soon can axon sprouting occur after an injury?
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Within 24 hours
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Are axon sprouts myelinated or unmyelinated?
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Axon sprouts are unmyelinated until later on in regeneration
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What is the critical gap width for neuron regeneration?
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2mm - otherwise the signals are too diluted to induce regeneration
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What is a neuroma?
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Neurites migrate aimlessly across a large gap. They can be stump neuromas or neuromas in continuity - very painful.
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How is CNS regeneration different/impaired compared to PNS regeneration?
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CNS axons undergo Wallerian degeneration, but usually do not up-regulate RAG to support regeneration. They often have many collateral branches so even with losses they still receive signals, so no "regeneration" signal.
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How does having oligodendrocytes in the CNS, vs Schwann cells, affect regeneration?
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Oligodendrocyte myelin takes much longer to degenerate, and myelin is associated with inhibitors of axonal regeneration, promotes proliferation of astroglia (creating a glial scar), which creates further barriers.
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List three oligodendrocyte-derived myelin associated inhibitors.
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Nogo (associated with stopping growing neurites and AI disorders like MS)
Myelin-Associated Glycoproteins (MAG) Oligodendrocyte-myelin glycoprotein |
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Define "Motor unit"
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A single motor neuron together with all of the muscle fibers that it innervates.
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How do fine and coarse motor movements differ in neuron number?
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There are more neurons with fine motor movements - each has a small patch of innervation, allowing for very specific movements - more often lost with injury
Coarse motor movements - each neuron has a large patch of innervation, allowing for more coordinated movements |
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How do Osmium Tetroxide stained nerve cross sections differ, between healthy and regenerated sections?
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Healthy sections - thicker myelin staining, fewer in number
Regenerated sections - thinner myelin staining, more in number |
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List stains for axons.
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Nauta, Fink-Heimer
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Name a stain for degenerating myelin.
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Marchi
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Name a stain for non-degenerating myelin (absence = anterograde degeneration)
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Weil, Weigert technique
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How does degenerating myelin appear differently under EM?
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Thick, very irregular border
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