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312 Cards in this Set
- Front
- Back
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Purpose of Nervouse System
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-To RECEIVE and INTERPRET all outside stimuli
-INTEGRATE info from outside to inside -INITIATE appropriate responses to environment |
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One neuron nervous system
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-Single sensori-motor neuron (receives and initiates response)
-2 features: irritability and conductivity -Modified ectoderm |
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What are 2 cardinal features of the one-neuron system?
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Irritability and Conductivity
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Two-Neuron Nervous System
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-Sensory (Afferent)
-Motor (efferent): within organism -All or none response Ex: monosynaptic muscle stretch reflex |
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Three-Neuron Nervous System
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-Intermediate neuron (interneuron) between motor and sensory
-Higher order synapse on to modify response -Synapse on other interneurons *Allows more processing and flexibility-->SPINAL CORD AND BRAIN |
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Peripheral Nervous System
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-Sensory Input
-Motor Output -Autonomic (Sym, Parasym, Enteric nervous system) |
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Central Nervous System
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(Spinal cord and brain)
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What does the spinal cord contain?
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-Sensory axons carrying sensory info from the periphery to brain
-Cell bodies of motor neurons, which innervate skeletal muscle -Interneurons, which mediate sensory, motor and autonomic info -Ascending and descending fiber tracts |
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What does the brain consist of?
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-Brain stem: medulla, pons, and midbrain
-Cerebellum -Forebrain: diencephalon, telencephalon |
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Role of Brain Stem
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-Receives sensory input from head and neck musculature
-Autonomic control to head, neck, and visceral organs -Integrates and coordinates vital functions: consciousness, respiration, circulation, body tone, eye movements |
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Cerebellum
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Plays a major role in smoothing out and coordinating motor activity
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Diencephalon
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Thalamus and hypothalamus
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Telencephalon
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Olfactory system, limbic system, basal ganglia, neocortex
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Meninges
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Pia, Arachnoid, Dura Mater
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Pia Mater
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Innermost layer, which adheres to the brain surface and follows all convolutions (usually can't see)
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Arachnoid
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Intermediate layer
-Stretches across sulci -CSF fluid is found in the subarachnoid space |
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Dura
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(Pachymeninges)
Tough, outermost layer, tightly adhered to skull -Venous sinus located between two layers |
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How much cardiac output goes to the brain?
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20%=Due to metabolic high demand
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Anterior Circulation of the brain
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-Internal Carotid Arteries (Anterior and Middle Cerebral Arteries)
-Supply the frontal lobes, superior temporal lobes, basal ganglia |
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Poster Circulation of the Brain
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-2 Vertebral Arteries-->unite to form the basilar arteries-->branches to form the 2 posterior cerebral arteries
--> Superior Cerebellar arteries, anterior inferior cerebellar arteries branch off the basilar artery -->Posterior inferior cerebellar arteries branch off vertebral arteries (supply cerebellum and brain stem) -Supplies the brain stem, cerebellum, diencephalon, occipital lobes, inferior temporal lobes |
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Circle of Willis
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-Communication between anterior and posterior circulations
-Consists of anterior and posterior communicating arteries *May limit size of infarction=collateral circulation |
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Venous Drainage: Where does the capillary blood from the brain drain into?
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Superficial and deep cerebral veins
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Venous Drainage: What is the major deep cerebral veins in the brain?
-->Where do these veins drains? |
-Internal Cerebral Vein
-Basal Vein of Rosenthal -Great Vein of Galen -->Drain into the venous sinuses then into the internal jugular vein |
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Basal Vein
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Receives inputs from middle cerebral and others
-Drains part of the frontal lobe, insula, basal ganglia, and hippocampal gyrus |
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Internal Cerebral Veins
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-Run under the fornix, over the stria medullaris on the thalamus
-2 types: terminal vein and choroid vein |
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Choroid Vein
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-Drains the hippocampus, fornix, and corpus callosum
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Terminal Vein
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-Drains the caudate nucleus and thalamus
-Located between the thalamus and the caudate nucleus |
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Middle Cerebral Veins
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-Drain into the cavernous sinuses
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Inferior Cerebral Veins
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-Drain the inferior surfaces of the hemisphere into either the superior sagittal sinus in the frontal lobe or the cavernous or the petrosal sinuses for temporal lobe
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Superior Cerebral Veins
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-Drain the superior, lateral, and medial surface and terminate in the superior sagittal sinus
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Where do the basal veins and internal veins form the great cerebral vein of Galen?
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At the splenium of the corpus callosum
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All the venous blood of the brain drains into the ______ ____ _____ ____ ___.
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Venous sinuses of the dura
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Where does the superior sagittal sinus receive blood from?
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-Superior cerebral veins and superiro dura, CSF via the arachnoid villi
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What joins at the confluence of sinuses?
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-Transverse sinus
-Occipital sinus -Superior sagittal sinus |
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Where does the occipital sinus begin?
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Near the margin of the foramen magnum
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Where is the straight sinus located?
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Along the attachment of the falx cerebri to the tentorium cerebelli
-Ends in te transverse sinus |
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Where does the inferior sagittal sinus run?
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Above the corpus callosum
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The cavernous sinuses, lying just laterally to the ____ _____, drain into the transverse sinuses via the ____ ____>
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-Pituitary stalk
-Petrosal sinuses |
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How does blood drain from the brain to heart?
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Internal Jugular Vein
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What supplies arterial blood to the corpus callosum?
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Anterior Cerebral Artery
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What does occlusion of the anterior cerebral artery cause?
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Generally results in paralysis of the lower body of the opposite side
(The area supplied by the ACA is the "leg" area of motor cortex) |
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What supplies blood to the internal capsule?
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Middle Cerebral artery
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What can occlusion of the middle cerebral artery cause?
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Occlusion of deep branches can causes PARALYSIS and LOSS OF SENSATION of much of the CONTRA-LATERAL BODY
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What supplies the ventral frontal-pareital area?
-->What can occlusion in this areas cause? |
Middle Cerebral Artery
--> Loss of function of speech, somatic sensation, from upper body and head and movement of these parts |
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Posterior Cerebral Artery: What can occlusion cause?
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-Partial Blindness (due to PCA supplying the occipital cortex)
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What supplies the hypothalamus, subthalamus, most of the thalamus, and rostral basal ganglia?
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Central Arteries
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What does the choroidal arteries supply?
-->Why is it of clinical importance? |
-Choroid Plexus, hippocampus, much of the globus pallidus, amygdala, and internal capsule
-->High Susceptibility to Thrombosis |
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What does the anterior and posterior spinal arteries supply?
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-Spinal Cord
-Parent Artery-Vertebral - most of the Pons and Medulla |
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What are the major venous sinuses?
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-Superior and Inferior sagitall sinuses
-Straight sinus -Transverse Sinus -Sigmoid Sinus |
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Describe CSF.
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-Ultrafiltrate of plasma that provides a hydraulic cushion to protect the brain
-May provide communication channel for neurotransmitters |
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Where is CSF found?
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-4 cerebral ventricles
-Subarachnoid Space |
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What secretes CSF?
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Choroid Plexus located in four ventricles
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Describe where and how CSF flows through brain?
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-From 2 Lateral Ventricles-->Foramina of Monro-->3rd ventricle-->Cerebral aqueduct-->4th ventricle-->Foramina of Luschka and Magendie-->Subarachnoid Spave via arachnoid granulations
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Where does the superior sagittal sinus receive blood from?
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-Superior cerebral veins
-Superior dura -Cerebral spinal fluid via the arachnoid villi |
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Where does the blood from the cavernous sinuses flow into?
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-Petrosal sinuses then into the internal jugular vein back to the heart
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Describe the anatomical properties of a neuron.
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-Cell Body (site of protein synthesis)
-Neurites: dendrites and axons |
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What are contained within the soma and dendrites?
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Nissl bodies (RER)
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Where is the site of initiation of action potential in an axon?
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Initial segment
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Graded Potential
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-Passive voltage change in the membrane potential due to excitatory or inhibitory stimuli
-May undergo spatial and temporal summation to effect a response at the axon hillock |
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Name excitatory neurotransmitters
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-Glutamate, Aspartate
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Name inhibitory amino acids
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GABA, glycine
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Function of Glia (General)
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-Located in CNS and PNS
-Insulate, separate and protect neurons -Assist metabolically |
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Astrocytes
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-Form scar tissue in response to injury (gliosis)
-Participate in blood brain barrier -Insulate and separate nerve cell bodies -Provide cytoskeleton framework within the brain -Regulate the ionic milieu by sequestering potassium -->Can proliferate and cause tumor |
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Oligodendrocytes
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-Produce myelin for CNS
-May myelinate one segment of many different axons |
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Microglia
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-Small phagocytes which respond to CNS injury
-May be mesodermal origin |
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Ependymal cells
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-line of ventricles of the brain
-cilia on their surface help move CSF through the ventricular system |
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Schwann Cells
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-Produce myelin for PNS axons
-Can myelinate only one segment of one peripheral axon -Separate and insulate non-myelinated axons in PNS -Phagocytose debris following nerve injury |
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Satellite cells
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-Small glia found in dorsal root ganglia, which support primary sensory cell bodies located in these ganglia
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Where does CSF go after it exits the formamina luschka and foramen magendia?
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Enters the cisterna magna then the arachnoind granulations (one-way valves)
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Brain: Three Major Parts Based on Embryological origins
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-Prosencephalon
-Mesencephalon -Rhombencephalon |
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Divisions of Prosencephalon.
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-Telencephalon
-Diencephalon |
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What is the largest subdivision of the brain and what are its 4 major systems?
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-Neocortex
-Basal Ganglia -Limbic System -Olfactory System |
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What is the responsibility of the neocortex?
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-Initiating voluntary motor activity
-Integrating sensory information |
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What type of higher functions does the neocortex perform?
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-Language, memory, abstraction, reasoning, individual's personality
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The neocortex is a mantle of gray matter that contains ___ ____ of cells.
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6 layers
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What is the neocortex divided into?
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4 Lobes: Frontal, Parietal, Occipital, Temporal
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The ______ separates the frontal and parietal lobes.
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Central Sulcus
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The ____ separates the frontal and parietal lobes from the temporal lobe.
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Sylvian Fissure
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The _____ on the medial surface of the brain separates the parietal and occipital lobes.
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Parieto-Occipital fissure
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What does the frontal lobe contain?
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Primary motor strip (precentral gyrus), secondary motor strip (pre-precentral gyrus), frontal eye fields that control voluntary eye movements
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What does the parietal lobe contain?
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Primary sensory strip (postcentral gyrus)
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What does the temporal lobe contain?
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Auditory cortex (transverse gyrus of Heschl)
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What does the occipital lobe contain and what is it separated by?
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Primary Visual cortex, separated by calcarine fissure
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Where is language localized?
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Dominant (left) hemisphere: Broca's, Wernicke's
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Broca's area
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-Lateral surface of dominant frontal lobe
-Controls the production of language |
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Wernicke's area
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-Near the supramarginal and angular gyri on lateral surface of the dominant temporal lobe
-Controls the understanding of language |
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Association cortex
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Primary motor and sensory modalities are integrated
-Located in all four lobes of brain |
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Where is the motor association cortex found?
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Frontal lobe
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Where is the sensory association cortex locate?
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In parietal, temporal, and occipital lobes
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Components of Basal Ganglia
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-Caudate nucleus
-Putamen -Globus Pallidus |
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What is the job of the basal ganglia?
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Allow the cortex to select wanted patterns of movement, and to suppress unwanted patterns of movement
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What makes up the striatum?
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Caudate nucleus and putamen
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What makes up the lentiform nucleus?
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Putamen and globus pallidus
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What is the job of the limbic system?
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Control Emotional resposiveness and affective behavior, resulting in an individualized interpretive response to external and internal stimuli
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What is the major output of the limbic system?
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Hypothalamus
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What does the hypothalamus control?
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Autonomic nervous system and Neuroendocrine secretions
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What are the corticolimbic structures?
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Hippocampus, Parahippocampal gyrus, cingulate cortex, prefrontal cortex
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What are the subcortical structures?
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Amgydala, septum, nucleus basalis of Meynert, Anterior perforated substance
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Describe the Papez Circuit and its function.
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Function: Incorporating new memory
Hippocampus-->fornix-->Anterior Nucleus of the thalamus-->cingulate cortex-->hippocampus |
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What occurs with bilateral lesions to the Papez circuit?
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Inability to incorporate new memory
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What does the olfactory system consist of?
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Olfactory bulb and tract, Olfactory striae, and the uncus
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The olfactory system has major input into the _____ _____.
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Limbic System
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What is the only system that bypasses the thalamus to the cortex?
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Olfactory system
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What makes up the diencephalon?
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Thalamus
Hypothalamus Subthalamus Epithalamus |
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Thalamus
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-Mjr sensory and motor relay station for the cortex=Gateway
-All sensory modalities (except for olfactory) and all motor relay info form the cerebellum and basal ganglia, and limbic info are processed by the thalamus before reaching the cortex |
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Hypothalamus
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-Location: lies ventral to thalamus and surrounds the 3rd ventricle
-Mjr output structure for the limbic system (neuroendocrine and autonomic) -Visceral regulatory areas: control various visceral activites |
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What is the head nucleus of the autonomic nervous system?
-->What does it influence |
Hypothalamus
-->Sympathetic and Parasympathetic output with respect to limbic inputs |
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What does the hypothalamus' neuroendocrine function include?
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Oxytocin, Vasopressin
-Hormonal Release -Inhibiting factors: CRF, GnRH, TRH, dopamine into the hypophyseal-portal system which control the release of the anterior pituitary hormones into the blood |
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What visceral activities does the hypothalamus do?
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Feeding, drinking, reproduction, thermoregulation
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Subthalamus
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-Integrally related to the basal ganglia
-Direct connections with the globus pallidus |
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What does a lesion in the subthalamus cause?
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-Hemiballismus: a involuntary movement disorder in the contralateral limbs
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What does the epithalamus consist of?
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-Pineal gland, habenular nuclei, habenular commisure
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What does the epithalamus have significant connection to?
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Limbic
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Pineal Gland
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-Part of the Epithalamus
-Secretes melatonin -Tumors of the pineal gland compress the pretectum and cerebral aqueduct, resulting in paralysis of upgaze and obstructive hydrocephalus (Parinaud's syndrome) |
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Parinaud's syndrome
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Tumors of the pineal gland compress the pretectum and cerebral aqueduct, resulting in paralysis of upgaze and obstructive hydrocephalus
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Name the parts of the brain stem
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-Mesencephalon (midbrain)
-Rhombencephalon (hindbrain): metencephalon (pons and cerebellum), myelocephalon (medulla) |
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What does the brain stem contain?
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Ascending sensory, Descending motor fiber tracts, Cranial nerve nuclei, secondary motor and sensory nuclei, autonomic pathways and "centers", reticular formation
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3 Anatomical regions of the brain stem
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Tectum (roof), Tegmentum (Core), Base
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Tectum
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(Roof)
-Portion of the midbrain dorsal to the cerebral aqueduct and consisting of the superior and inferior colliculi (quadrigeminal bodies) |
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Tegmentum
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-The core of the brainstem located between the tectum and base of the midbrain, pons and medulla
-Contains the reticular formation, cranial nerve nuclei, and ascending lemniscal sensory tracts |
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Base
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-the most ventral portion of the midbrain, pons and medulla
-Contains the descending motor tracts |
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What are located at the base of the brainstem?
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-Cerebral peduncles, basis pontis, medullary pyramids
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What 5 functional components can the brainstem be divided
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Motor, sensory, autonomic, cerebellar, and reticular formation
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Name the lower motor neurons
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CN III, IV, V, VI, VII, nucleus ambiguus IX, X, spinal accessory XI, XII
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Name the nuclei for upper motor neurons
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Red Nucleus, superior and inferior colliculi, lateral and medial vestibular, and medial pontine and medullary reticular formation
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Name some descending tracts
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Corticospinal tract, corticobulbar tract, rubrospinal tract, lateral and medial vestibulospinal tracts, pontine and medullary reticulospinal tracts, ans the tectospinal tract
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What is the only upper motor neuron tract that synapses on the brain stem lower motor neuron?
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Corticobulbar
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UMN Nucleus: Primary and Secondary Cortex (1)
What's the Descending UMN Tract and Target LMN? |
Descending UMN Tract: Corticospinal
Target LMN: Flexor LMN |
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UMN Nucleus: Primary and Secondary Cortex (2)
Whats the Descending UMN tract and Target LMN? |
Descending UMN Tract: Corticobulbar
Target LMN: Brain stem LMN |
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UMN Nucleus: Red Nucleus
What's the Descending UMN tract and Target LMN? |
Descending UMN Tract: Rubrospinal
Target LMN: Flexor LMN |
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UMN Nucleus: Superior and Inferior colliculi
What's the Descending UMN tract and Target LMN? |
Descending UMN Tract: Tectospinal
Target LMN: Cervical LMN |
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UMN Nucleus: Lateral Vestibular
What's the Descending UMN tract and Target LMN? |
Descending UMN Tract: Lateral vestibulospinal
Target LMN: Extensor LMN |
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UMN Nucleus: Medial Vestibular
What's the Descending UMN tract and Target LMN? |
Descending UMN Tract: Medial Vestibulospinal
Target LMN: Cervical LMN |
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UMN Nucleus: Medial Vestibular
What is the Descending UMN Tract and Target LMN? |
-Descending UMN Tract: Medial vestibulospinal
Target LMN: Cervical LMN |
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UMN Nucleus: Pontine Reticular formation
What is the Descending UMN Tract and Target LMN? |
-Descending UMN Tract: Pontine reticulospinal
-Target LMN: Extensor LMN |
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UMN Nucleus: Medullary reticular formation
What is the Descending UMN Tract and Target LMN? |
-Descending UMN Tract: Medullary reticulospinal
-Target LMN: Flexor LMN |
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Sensory Modality: Somatosensory Protopathic
What are the Secondary Sensory Nucleus and Ascending Lemniscus? |
Secondary Sensory Nucleus: Dorsal horn of spinal cord
Ascending Lemniscis: Spinal Lemniscus |
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Sensory Modality: Sematosensory Epiciric
What are the Secondary Sensory Nucleus and Ascending Lemniscus? |
-Secondary Sensory Nucleus: Nuclei gracilis and cuneatus
-Ascending Lemniscus: Medial Lemniscus |
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Sensory Modality: Taste
What are the Secondary Sensory Nucleus and Ascending Lemniscus? |
-Secondary Sensory Nucleus: Nucleus solitarius
Ascending Lemniscus: Solitario-thalamic tract |
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Sensory Modality: Facial Sensory Protopathic
What are the Secondary Sensory Nucleus and Ascending Lemniscus? |
Secondary Sensory Nucleus: Descending nucleus of CN V
Ascending Lemniscus: Trigeminal lemniscus |
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Sensory Modality: Facial Sensory Epicritic
What are the Secondary Sensory Nucleus and Ascending Lemniscus? |
Secondary Nucleus: Main sensory nucleus of CN V
Ascendning Lemniscus: Trigeminal lemniscus |
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Sensory Modality: Auditory
What are the Secondary Sensory Nucleus and Ascending Lemniscus? |
Secondary Sensory Nucleus: Dorsal and Ventral cochlear nuclei; Acessory auditory nuclei
Ascending Lemniscus: Lateral lemniscus |
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Sensory Modality: Vestibular
What is the Secondary Sensory Nucleus? |
Superior, inferior, lateral and medial vestibular nuclei
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What does the superior cerebellar peduncle connect?
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Midbrain with the cerebellum
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What does the middle cerebellar peduncle connect?
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Pons withe cerebellum
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What does the inferior cerebellar peduncle connect?
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Medulla with the cerebellum
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What can lesions to the peduncles or the cerebellum cause?
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-Produce ataxia with a course action tremor
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Reticular Formation
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-Forms core of the entire brain stem
-Responsible for maintaining consciousness, maintaining general muscle tone and posture, processing noxious stimuli, regulating major visceral functions |
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What is the medial portion of reticular formation's function?
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Motor function
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What is the lateral portion of reticular formation's function?
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Sensory function
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Where is the autonomic portion of reticular formation's function?
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Not as precisely localized and is found scattered throughout the entire reticular formation
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Describe the motor components of reticular formation.
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-Maintenance of muscle tone and posture by means of the pontine (extensor) and medullary (flexor bias) reticulopsinal
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Describe the sensory components of reticular formation.
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-Processing slow pain info via te spinoreticular tract
-Maintenance of consciousness: awakens the cortex in response to noxious stimuli |
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Describe the autonomic components of reticular formation.
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Control blood pressure, respirations, cardiac functions, and GI function
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Function of cerebellum
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-Comparator and coordinates and smoothes out motor activity= compares the position of body parts in space with the intended movement of those body parts
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What does the cerebellum consist of?
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Vermis (trunk), Cerebellar hemispheres (arm and leg)
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To what vertebra does the spinal cord extend?
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Extends from foramen magnum to the L1 vertebral level
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Segments of Spinal Cord
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8 cervical
12 thoracic 5 lumbar 5 sacral 1 coccygeal |
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Dorsal funiculus contains mainly _____ _____ ____.
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Ascending somtaosensory tracts
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Lateral and ventral funiculi contain ___ ___ __.
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Both ascending sensory and descending motor tracts
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Which Rexed laminate contains secondary sensory cells?
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Laminae I-V
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What does the PNS consist of?
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Peripheral nerves, primary sensory cell bodies found in the dorsal root ganglia, sensory receptors, neuromuscular junctions, autonomic ganglia cells
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What does the PNS contain?
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motor, sensory, autonomic componenst
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Motor Components of PNS
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Axons of lower motor neurons and the neuromuscular junction
(Ach is a neurotransmitter at the neuromuscular junction) |
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Sensory Components of PNS
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Sensory receptors, primary sensory axons and primary sensory cell bodies (found in DRG and CN ganglia)
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Autonomic components of PNS
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Sympathetic and Parasympathetic preganglionic axos, ganglion cells, and postganglionic axons
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Sympathetic Nervous System
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-System that arouses the organism to prepare for "fight or flight" activity
-Thoraco-lumbar system: preganglionic cell bodies located in intermediolateral cell column of spinal cord segments T1-L2 |
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Where are postganglionic cell bodies found for the sympathetic nervous system?
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-Sympathetic chain ganglia (found at all nerve levels, attached to spinal nerves by gray and white rami communicantes)
-Sympathetic collateral ganglia (from splachnic nerve that exit the sympathetic chain ganglia) |
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____ is the preganglionic sympathetic neurotransmitter, and _______ is the postganglionic sympathetic neurotransmitter.
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Ach, NE
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Parasympathetic Nervous System
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-Mainly homeostatic, allowing for maintenance and repair of the body
-Cranio-sacral (S2-4) |
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CN III's Target
-Name the nucleus and ganglion? |
-Target: Pupillary constriction, accomodation
-Nucleus: Edinger Westphal -Ganglion: Ciliary |
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CN VII's Target
-Name the nucleus and ganglion? |
-Target: 1) Lacrimal glands 2) Submandibular and sublingual salivary glands
-Nucleus:Superior salivatory -Ganglion: 1) Pterygopalatine 2) Submandibular |
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CN IX's Target
-Name the nucleus and ganglion? |
-Target: Parotid Gland
-Nucleus: Inferior salivatory -Ganglion: Otic |
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CN X's Target
-Name the nucleus and ganglion? |
-Target: Heart, lung, liver, gut, splenic flexure
-Nucleus: Dorsal motor nucleus of vagus nerve -Ganglion: Intramural of organ |
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_______ is the preganglionic parasympathetic neurotransmitter, and ________ is the postganglionic parasympathetic neurotransmitter.
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ACh, ACh
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Somatic Efferent (SE) column
|
-Modality: LMN myotomes
-Central Connections: Motor cortex, Cortiocobulbar tract -Brain Stem Nucleus: III, IV, VI, XII -Cranial Nerve: III, IV, VI, XII -Ganglion: None -Target: Extraocular muscles, Tongue |
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Special Visceral Efferent (SVE) column
|
-Modality: LMN, Brachial arches
-Central connections: Motor cortex, corticobulbar tract -Brain Stem Nucleus: V----VII---Nucleus ambiguus -Cranial Nerve: V ---VII, IX--- X -Target: Muscles of Mastication, Facial Expression, Pharynx, Larynx |
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General Visceral Efferent (GVE) column
|
-Modality: Parasympathetic
-Central Connections: Hypothalamus -Brain Stem Nucleus: Edinger-Westphal Superior Salivatory---Inferior Salivatory, Dorsal motor N. of X -Cranial Nerve: II, VII-----IX, X -Ganglion: Ciliary, Pterygopalatine, Submandibular----Otic, Intramural -Target: Pupil constrictor, lacrimal glands, submandibular and sublingual sal. glands, parotid glands, heart, lung, gut |
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Somatic Visceral Afferent (SVA) column
|
-Modality: Taste
-Central Connections: VPM via solitario-thalamic tract -Brain Stem Nucleus: Nucleus solitarius-rostral portion -Cranial Nerve: VII, IX, X -Ganglion: Geniculate, petrosal, nodose -Target: Ant 2/3 tongue. Post 1/3 tongue, epiglottis |
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General Somatic afferent (GSA) column
|
-Modality: Facial sensation
-Central connections: VPM-trigeminal lem---VPM-trigimenal lem -Brain Stem Nucleus: Main sens N.V---Spinal nucleus V -Cranial Nerve: V1,2,3---V1,2 (VII, IX, X) -Ganglion: Trigeminal----Trigeminal (Gen, Petr, Nod) -Target: Epicritic-face, Protopathic-face, pharynx, layrnx |
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Special Somatic Afferent (SSA) column
|
-Modality: Hearing, Balance
-Central Connections: Lat lem, MCB, Ctx, MLF, Cbl, VST, reticular formation -Brain Stem Nucleus: Cochlear N: D and V---Vestibular N: S, I, L, M -Ganglion: Spiral, Scarpa's (Vestibular) -Target: Cochlea, Vestibular apparatus |
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What does the motor system consist of?
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Lower motor neurons, upper motor neurons, several specialized structures that help coordinate patterns of motor activity
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5 Parts of Motor System
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Pyramidal system (corticospinal), extra-pyramidal system ,corticobulbar, cerebellum and basal ganglia
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The motor system is a two-neuron system, containing _____ and _____.
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UMN, LMN
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Where are UMN located?
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Cerebral cortex, brain stem
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Where are LMN located?
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Ventral horn of spinal cord, several brain stem cranial motor nerve nuclei
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Do the cerebellum and basal ganglia talk to LMN directly?
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NO
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Corticospinal (Pyramidal) System
|
Betz cells in Primary motor cortex, Secondary motor cortex---< Cervical,Lumbosacral LMS, interneurons
Course: Motor Cortex-- > Posterior Limb of Internal Capsule ---> Cerebral peduncle --->Basis pontis ---> Pyramids --X--->Lateral Funiculus Decussates: at the pyramidal at the caudal portion of the medulla (one axon in length) Flexor Bias |
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Telencephalon: Tract Location
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Corona radiata
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Diencephalon: Tract Location
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Internal Capsule (posterior limb)
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Midbrain: Tract location
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Cerebral peduncle
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Medulla: Tract Location
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Pyramids (Decussation)
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Spinal Cord: Tract Location
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Lateral Funiculus of spinal cord
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Rubrospinal Tract
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Course: Red Nucleus (receives input form cerebral cortex and cerebellum)--X---brainstem---> lateral funiculus of spinal cord---< indirectly via interneurons on Spinal LMNs
Flexor Bias, assists corticospinal tract in providing motor control to distal extremeties |
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What do lesions to the rubrospinal tract produce (solely on this tract)?
|
Decorticate: FLEXION fo the Upper extremities and EXTENSION of the lower extremities
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Lateral Vestibulospinal tract
|
Course: Lateral Vestibual nucleus (cells of origin with input from vestibular apparatus) ---> ipsilaterally through brainstem and ventral funiculus of spinal cord ---< directly and via interneurons of spinal LMNs
Extensor bias, imp't in the maintenance of antigravity tone and upright posture Inhibited by red nucleus |
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What does a lesion of the red nucleus cause on the lateral vestibulospinal tract?
|
(Red nucleus inhibits lateral vestibulospinal tract)
Decerebrate posturing: Produce uninhibited extension of all four extremities |
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Pontine recticulospinal tract
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Course: Pontine reticular formation (cells of origin located here, receives input form spinoreticular sensory fibers) ---> ipsilaterally through brain stem, ventral funiculus of spinal cord ---< via interneurons on spinal LMNs
Extensor bias, assists the lateral vestibulospinal tract in maintaining extensor tone, particularly in response to cutaneous noxious stimuli |
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Medullary Reticulospinal tract
|
Course: Medullary reticular formation (cells of origin, depesn upon cortical input) ---> ipsilaterally thru brainstem, ventral funiculus of spinal cord ---< via interneurons on spinal LMNs
Flexor bias, augmenting the effects of corticospinal and rubrospinal LMNs |
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Medial Vestibulospinal tract
|
Course: Medial vestibular nucleus (cells of origin, input from vestibular apparatus) ---> descends ipsilaterally thru brain stem, ventral funiculus of cervical spinal cord ----< DIRECTLY on cervical LMNs
Coordinate Head and Neck motion with vestibular input for maintenance of head pos'n |
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Tectospinal tract
|
Course: Superior and inferior colliculus (cells of origin, visual and auditory input) --X-->Descends in medial-dorsal brain stem and ventral cervical spinal cord ----< via interneurons on Cervical LMNs
Coordinate head and neck motion with visual, and to a lesser extent auditory, stimuli for maintenance of head position |
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Corticobulbar: How does it differ from the corticospinal tract?
|
-Innervates brain stem
-Travels in GENU of internal capsule -Provides both ipsilateral and contralateral innervation to all brain stem LMNs with the exception of LMNs supplying the lower half of the face |
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Describe facial LMNs of corticobulbar tract.
|
-Lower facial LMNs receive only CONTRALATERAL UMN innercation via the corticobulbar tract, and hence unilateral lesions to this tract result in CONTRALATERAL LOWER FACIAL WEAKNESS
(Upper facial strength remains normal because the ipsilatearl projection of the corticobulbar tract to the upper half of the facial nucleus remains intact) |
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Pseudobulbar palsy
|
Bilateral cortical lesions produce bilateral corticobulbar tract dysfunction, manifesting as generalized facial bulbar weakness with difficulty speaking and swallowing (spastic dysarthria and dysphagia)
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Cerebellum
|
-A "comparator", coordinates and smoothes out motor activity by comparing the position of body parts in space with intended movement of those body parts
- |
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Vermis
|
Coordinates the trunk
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Paravermis
|
Coordinates proximal appendicular (arm and leg) movement
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cerebellar hemispheres
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Coordinates distal appendicular movements
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What do cerebellar lesions cause?
|
-Ataxia: uncoordinated movements
-Dysmethria: difficulty judging distances when reaching for objects -truncal instability |
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What does a lesion to the sensory input to the cerebellum cause?
|
Usually ipsilateral=ipsilateral ataxia
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Layers of the cerebellar cortex
|
-Molecular layer (outermost layer): contains dendrites of Purkinje cells, parallel fibers that arise from granule cells, climbing fibers that arise from the inferior olivary nucleus, and basket and stellate cells
Purkinje layer: contains purk. cells -Granule cell layers: contains granule cells, mossy fibers and Golgi II |
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Layers of cerebellum (2)
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Cortex (grey matter)
Deeper white matter |
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What are the major source of output for the cerebellum?
|
Deep cerebellar nuclei
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What are the major output cell of the cerebellar cortex?
|
Purkinje cells
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Name the 4 deep cerebellar nuclei
|
-Fastigual: vermis outflow
-Globose and emboliform nuclei: paravermis outflow -Dentate nucleus: cerebellar hemisphere outflow |
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Where do the inputs of the cerebellum come from?
|
-Spinal Cord containing proprioceptive info
-Cerebral cortex, containing info about intended motor activity -->the cerebellum then compares these two inputs and feeds this info back to the cerebral cortex UMNs via the thalamus=smooth and coordinated movement |
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Types of fibers for cerebellar input
|
-Climbing fibers
-Mossy fibers |
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Climbing Fibers
|
Carries input info from the inferior olive only to the cerebellum
Send to deep cerebellar nuclei-Synapse directly on Purkinje cell dendrites |
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Mossy fibers
|
Carries input info from all other sources other than the inferior olive to the cerebellum (spinocerebellar tracts, motor cortex, vestibular nuclei, reticular formation, trigeminal system, and superior and inferior colliculi)
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How do mossy fibers send to collaterals to the deep cerebellar nuclei?
|
Mossy fibers first synapse on granule cells whose axons, called parallel fibers, synapse on Purkinje cell dendrites
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What modulate the climbing fiber, mossy fiber and parallel fiber input into the cerebellar cortex?
|
stellate cells, basket cells, Golgi II cells
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The _______ is the major source of output form the cerebellar cortex, and this output is _____.
|
Purkinje cell, inhibitory
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Where does coarse adjustment occur for the cerebellum?
|
Deep cerebellar nuclei
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Where does fine adjustment occur?
|
Cerebellar cortex
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Where do most inputs enter the cerebellum?
|
Inferior and Middle cerebellar peduncles
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Where do most outputs exit the cerebellum?
|
Via the superior cerebellar peduncle
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Cerebellar Peduncle: Inferior
Input? |
Dorsal spinocerebellar tract, cuneocerebellar tract, rostral spinocerebellar tract, vestibular nuclei, reticular formation, trigeminal system, inferior olive
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Cerebellar Peduncle: Inferior
Output? |
Vestibular nuclei
Reticular formation |
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Cerebellar Peduncle: Middle
Input? |
Cerebral cortex (via pontine nuclei)
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Cerebellar Peduncle; Superior
Input? |
Ventral spinocerebellar tract,
superior and inferior colliculi, reticular formation, trigeminal system |
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Cerebellar Peduncle: Superior
Output? |
Nucleus VL of thalamus, red nucleus, reticular formation
|
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Dorsal and ventral spinocerebellar tracts
|
Carry proprioceptive info from spinal level T6 and below
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Cuneocerebellar and rostral spinocerebellar tracts
|
Carry proprioceptive info from above spinal level T6
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What do the dorsal spinocerebellar and cuneocerebellar tracts process?
|
Muscle spindle info
-This info is carried into the spinal cord by group Ia and group sensory fibers |
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What do the ventral and spinocerebellar tract process?
|
Golgi tendon organ info, info is carried into the spinal cord by group Ib sensory fibers
|
|
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Spinocerebellar tracts
|
-Two neuron chains
-Primary sensory neuron synapsing on a relay nucleus in either the spinal cord or brain stem |
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|
Vestibulo-cerebellum: What the embryonic name?
|
Archicerebellum
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|
|
Spino-cerebellum: What's the embryonic name?
|
Paleocerebellum
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|
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Ponto-cerebellum: What's the embryonic name?
|
Neocerebellum
|
|
|
Name some disorders of the basal ganglia.
|
(Movement disorders, excess or a paucity-smallness of movement)
Parkinson's disease, Huntington's disease, Tourette's syndrome |
|
|
5 Structures of the Basal Ganglia
|
Caudate nucleus, putamen, globus pallidus, substantia nigra, and subthalamus
|
|
|
Sensory component of Basal Ganglia
|
Striatum (caudate and putamen)=receives input
|
|
|
Motor component of Basal Ganglia
|
Globus pallidus
|
|
|
What does the striatum receive input from?
|
-Cerebral cortex, thalamus (mainly nucleus CM), brain stem rpahe nuclei, the substantia nigra
|
|
|
Where does the globus pallidus project its output?
|
To primary motor and premotor cortex via nuclei VL and VA of the thalamus
-->reciprocal connection with the subthalamus |
|
|
Where are lower motor neurons located?
|
Ventral horn of the spinal cord (anterior horn cells) and in brain stem cranial motor nerve nuclei
|
|
|
Nucleus: Ventral Horn
Nerve: ? Target: ? |
Nerve: Spinal Nerves
Target: Limb and trunk musculature |
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|
Nucleus: Oculomotor
Nerve: ? Target:? |
Nerve: CN III
Target: Extraocular muscles: SR, IR, MR, IO, Levator pelpebrae |
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|
Nucleus: Trochlear
Nerve:? Target? |
Nerve: IV
Target: Superior Oblique muscle |
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Nucleus: Abducens
Nerve: ? Target: ? |
Nerve: VI
Target: Lateral rectus muscle |
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Nucleus: Trigeminal motor
Nerve: ? Target:? |
Nerve: CN V
Target: Muscles of Mastication |
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|
Nucleus: Facial
Nerve: ? Target:? |
Nerve: VII
Target: Muscle of facial expression |
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|
Nucleus: Ambiguus
Nerve: ? Target: ? |
Nerve: CN IX, X
Target: Pharyngeal and laryngeal muscles |
|
|
Nucleus: Spinal accessory
Nerve:? Target:? |
Nerve: CN XI
Target: Sternocleidomastoid and trapezius |
|
|
Nucleus; Hypoglossal
Nerve: ? Target: ? |
Nerve: CN XII
Target: Tongue musculature |
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|
Primary sensory info entering the CNS forms 3 types of functional secondary sensory, called channels: ______, ____, ______
|
Reflex channels
Cerebellar channels Lemniscal (ribbon) channels |
|
|
Two types of reflex channels
|
Monosynaptic channels
Polysynaptic channels |
|
|
________ carry conscious sensory information to the cortex.
|
Lemniscal channels
|
|
|
Describe the three neuron system of the lemniscal channels
|
DRG or CN ganlia--Primary sensory axons--> Secondary sensory axons (brain stem or spinal cord)--> tertiary sensory axons
|
|
|
The somatosensory system carries and processes somatosensory information from the ____ and ____.
|
Trunk and limbs
|
|
|
What do the epicritic modalities include?
|
Fine, discriminative touch, position sense and vibration
|
|
|
What do the protopathic modalities include?
|
Poorly localized touch, and pain and temperature perception
|
|
|
What are the sensory receptors for the epicritic system include?
|
Encapsulated nerve endings: muscle spindles, Golgi tendon organs, Pacinian corpuscles, and Meissner's corpuscles
|
|
|
Where are the primary sensory cell bodies located for the epicritic system?
|
DRG
|
|
|
What part of the spinal cord does the epicritic system pass through? (somatosensory)
|
Dorsal funiculus (dorsal column)
|
|
|
Where does the epicritic system synapse with the nuclei gracilis and cuneatus? (somatosensory)
|
In medulla
|
|
|
(Somatosensory) The ________ are located medially and carry epicritic info from level T6 and below.
|
nucleus and fasciculus gracilis
|
|
|
(Somatosensory) The ______ are located lateral to nucleus and fasciculus gracilis and carry epicritic info from spinal level T6 and above.
|
Nucelus and fasciculus cuneatus
|
|
|
Course of Epicritic System (Somatosensory)
|
Encapsulated nerve ending receptor---> DRG---> Dorsal Funiculus--> Gracilis (Below T6) or Cuneatus (Above T6)--X--in--medulla (int. arcuate fibers)-- Medial lemniscus--> nucleus VPL of the thalamus---Corona radiata---> Primary sensory cortex
|
|
|
Protopathic (Spinothalamic) system: Fast pain and temperature (Somatosensory)
|
Receptors (A Delta fibers)---> DRG---<Rexed laminae I and V --X---in the anterior white commisure of spinal cord---> ascend contralateral lateral funiculus and brain stem as SPINOTHALAMIC TRACT---> nucleus VPL of the thalamus-----> corona radiata----->Primary sensory cortex
|
|
|
Protopathic (Spinothalamic) system: Slow pain (somatosensory)
|
Receptor (bare nerve endings=C fibers)---> DRG---< Rexed Laminae II, III (substantia gelatinosa)--< Rexed laminae IV, V (nucleus proprius), laminae VII (intermediate gray)--X-> Anterior White Commissure of the spinal cord--Ascend contralateral lateral funinculus---SPINORETICULAR TRACT of brain stem---> Reticular formation----> nucleus CM of the the thalamus (may send)----> secondary sensory cortex (SII) and non specific areas of cortex for further slow pain processing
|
|
|
Trigeminal Sensory System
|
Carries and processes sensory information from the face
|
|
|
Trigeminal Epicritic system
|
Trigeminal ganglion (primary cells)---> lateral pons via trigeminal nerve---< main sensory nucleus of CN V--X---> ascends trigeminal lemniscus to nucleus VPM of thalamus---> corona radiata---> latearl portion of the primary sensory cortex
|
|
|
Trigeminal Protopathic System (fast pain)
|
Trigeminal ganglion (primary cells) ---> Lateral pons via trigeminal nerve ---< descending nucleus of CN V ---X--> Trigeminal Lemniscus---> Nucleus VPM of the thalamus---> corona radiata--> lateral portion of the primary sensory cortex
|
|
|
Trigeminal Protopathic Sensory System (Slow pain)
|
Trigeminal ganglion (primary cells) ---> Lateral pons via trigeminal nerve ---< descending nucleus of CN V ---> Reticular formation (may project)---> nucleus CM of the thalamus---> secondary sensory cortex (SII)
|
|
|
What are the two modalities processed by the visceral sensory?
|
Taste and visceral sensation
|
|
|
What are the 3 cranial nerves involved with the taste system (visceral sensory)?
|
VII: Geniculate ganglion, ant. 2/3 of tongue
IX: petrosal ganglion, post. 1/3 of tongue X: nodose ganglion, epiglottis |
|
|
Course of taste system (visceral sensory)
|
Primary sensory afferents carrying taste info via CN VII, IX, X---> solitary tract in dorsal medulla--< rostral portion of nucleus solitarius-----ipsi----> solitario-thalamic tract---> nucleus VPM of the thalamus---> corona radiata---> Lateral portion of the post-central gyrus---> portion of insular cortex
|
|
|
Visceral sensation
|
Petrosal ganglion IX and nodose ganglion X (primary sensory cell bodies)--->Brain stem via CN IX and X-->Solitary tract in dorsal medulla--< caudal portion of the nucleus solitarius---> dorsal motor nucleus of CN X AND other medullary autonomic ctrs (allows reflex regulation of cardiovascular and respiratory responses)
|
|
|
The auditory system converts ____ ____ of sound into _____ ____. What else does it do?
|
-Mechanical energy, electrical signals
-Anaylzes these for tone, loudness, and timbre, and interprets these properties with respect to the understanding of speech |
|
|
What does the peripheral apparatus include?
|
Outer ear, middle ear, and inner ear
|
|
|
Outer Ear
|
Pinna and external ear canal
|
|
|
Middle Ear
|
Tympanic membrane, ossicels (malleus, incus, and stapes), muscles (tensor tympani (CN V), stapedius (CN VII))
|
|
|
Inner Ear
|
Oval window, round window, cochlea (scala vestibuli, scala tympani, scala media, helicotrema, basilar membrane, Reissner's membrane, tectorial membrane, Organ of Corti, inner and outer hair cells, perilymph, endolymph)
|
|
|
Where are the primary cell bodies for the cochlear nerve located?
|
Spiral (auditory) ganglion located in the spiral of the cochlea
|
|
|
Central auditory connections
|
CN VIII (spiral ganglion)--> Cochlear nucleus (pons)---> Lateral lemniscus--> Inferior colliculus (Midbrain)---> Medical geniculate nucleus (thalamus)---> transverse gyrse of Heschl (temporal lobe)
|
|
|
What accessory auditory nuclei are interposed between the cochlear nuclei and the lateral lemniscus in the pons?
|
Nucleus of lateral lemniscus, trapezoid body, and superior olivary nucleus
|
|
|
Superior olivary nucleus
|
IMPORTANT IN SOUND LOCATION
-Each of cells receives auditory input from both the right and left ears and integrates the temproal sequence of the sound striking each ear at a slightly different time. --> This allows one to localize sound on the azimuth (horizontal plane) |
|
|
What happens with a lesion in the one ear?
|
Only produce a generalized, bilateral diminution in auditory acuity
|
|
|
Where are the most common places for unilateral hearing loss lesions?
|
Peripheral auditory apparatus, cochlear nerve or cochlear nuclei
|
|
|
What does the vestibular system sense?
|
Changes in head and body position in space and uses this info in numerous ocular and somatic reflex circuits
|
|
|
What are the 2 type of receptors of the peripheral apparatus?
|
Those that sense angular acceleration
Those that sense linear acceleration |
|
|
Angular Acceleration Receptors(Visceral System)
|
Semicircular canals filled with endolymph with dilated portion on one end
-Ampulla contains hair cells that protude into a gelatinous substance=cupula -Hair cells have tonic rate of electrical firing--->any deflection results in a change in the baseline electrical firing rate, which then propaagtes down the vestibular nerve into the brain stem |
|
|
Linear acceleration (Visceral System)
|
Receptors: utricle and saccule
-Structures contain hair cells that have calcium carbonate crystals sitting on them -Moving head causes gravity to deflect the calcium and the attached hair cells=electrical potential that propagates down the length of the vestibular nerve into the brain stem |
|
|
Where are the primary sensory cell bodies for the vestibular system located?
|
Vestibular (Scarpa's) ganglion
|
|
|
Where do the axons from the vestibular ganglion synapse?
|
Superior, inferior, lateral, medial vestibular nuclei in the pons
|
|
|
Where do the sup, inf, lat, med vestibular nuclei project?
|
Spinal cord (lat and med vestibulospinal tracts), Cerebellum (vermis and flocculo-nodular lobe), Reticular formation (vomiting ctr in medullat), Extraocular muscles (via the longitudinal fasciculus (MLF) and CN nuclei II, IV, VI), medial geniculate body (conscious perception of orintaiton of the body in space)
|
|
|
What does the visual system do?
|
Transforms light energy into electrical energy by means of specialized cells located in the retina
|
|
|
What are the four different places that the axons from the retinal ganglion cells project?
|
Lateral geniculate nucleus of the thalamus, the pretectum of the midbrain, the superior colliculus, hypothalamus
|
|
|
Retinal ganglion cells axons destined for conscious perception of vision synapse in the _______.
|
Lateral geniculate of the thalamus---> optic radiations---> primary visual (striate) cortex located on the banks of the calcarine fissure
|
|
|
Pretectum
|
-Retinal ganglion cell axons involved with the pupillary light reflex bypass the lateral geniculate body and synapse via interneurons on the NUCLEUS OF EDINGER WESTPHAL in the midbrain--> ciliary ganglion--> pupillary constrictor muscle via CN III
|
|
|
Pupillary reflex is a ____ and _____ reflex; fiber crossing occurs in the ______, the ____ and in _____.
|
-Direct, consensual
-Optic chiasm, pretectum, posterior commissure |
|
|
Superior colliculus
|
Retinal ganglion cell axons involved with visual reflexes synase here
|
|
|
What 3 ares does the superior colliculus project?
|
Spinal cord (tectospinal), cerebellu, (sup cerebellar peduncle), pulvinar of the thalamus (which in turn projects to association visual corte)
|
|
|
Hypothalamus(visual system)
|
retinal ganglion cell axons project to the suprachiasmatic nucleus of the hypothalamus--> SETS CIRCADIAN LIGHT-DARK RHYTHMS (imp't for the secretions of many pitu hormones0
|
|
|
Lesion: Optic Nerve
|
Ipsilateral monocular blindness
|
|
|
Lesion: Optic chiasm
|
Bitemporal hemianopsia
|
|
|
Lesion: Optic tract
|
(VERY RARE)
contralateral homonymous hemianopsia |
|
|
Lesion: Lateral geniculate nucleus
|
Contralateral homonymous hemianopsia
|
|
|
Lesion: Temporal Optic radiations (Meyer's loops)
|
Contralateral superior quadrantanopsia (pie-in-the-sky defect)
|
|
|
Lesion: Parietal optic radiations
|
Contralateral inferior quadrantanopsia (pie-in-the-floor defect)
|
|
|
Lesion: Occipital cortex
|
Contralateral homonymous hemianopsia
|
