15 Neuroanatomy Overview - PSL302Y: Lecture 14, by Prof....

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Neuroanatomy Overview : Major Structures in CNS Neuron - Major fxnal component of CNS - Cell body (or soma ) - Dendrites : present if neuron receives synaptic input - Axon : present if neuron generates axn potential; conductive’ wire of CNS - Neither of these components necessary to make a neuron - I.e. Possibly no axon in sensory cells - Prototypical neuron has both - At terminal of axon is bouton : synapse w/ dendritic tree - Also on soma or an axon (presynaptic inhibition) - Both terminals make 1 synapse on the post-synaptic cell - Axon wraps around dendrites and making all kinds of synaptic contact - Called synapses en passant : axon continues along - Has these varicosities (bulges) full of vesicles and some mitochondria, release transmitters to post-synaptic dendrites at various locations Synapse en passant RP: reserve pool of vesicles RRP: readily releasable pool PSL302Y: Lecture 14, by Prof. MacKay Mon., Oct.18, 2010
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Spinal Cord : cross-section - Neuronal soma in s.c. all lodged w/i grey matter (butterfy shape, cross-section) - Surrounded by vertebrae - Central canal oF grey matter ±lled w/ cerebral spinal fuid (linked to IVth ventricle) - Soma in grey matter in dorsal horn and ventral horn - In humans, ventral horn also called anterior horn + dorsal horn as posterior horn - Btwn dorsal and ventral horns is the intermediate zone (link dorsal and ventral horns) - Surrounding the grey matter is white matter (Funiculus): Full oF axonal tracts (myelinated = lipid = white) - Subdivided into 3 regions: dorsal columns, lateral Funiculus + ventral Funiculus - Dorsal roots entering s.c. divides dorsal columns + lateral Funiculus - Ventral root exiting s.c. divides btwn lateral + ventral Funiculi - Dorsal roots carry aFFerents (sensory axons) - Cell bodies in dorsal root ganglions - Axons terminate in dorsal horn - Interneurons in intermediate zone - Ventral horns: motor neurons exit to go to muscles - Bony casing oF spinal cord: roots exit via holes in vertebrae - Dorsal root ganglia would sit outside holes (unprotected) Spinal cord: sagittal section - Segments oF s.c. de±ned by dorsal or ventral root - 1 dorsal + ventral root on each side - New dorsal root = new s.c. segment - Subdivide: cervical, thoracic, lumbar, sacral - S.c. not aligned w/ vertebrae that have same number scheme - Spinal cord is shorter than backbone & terminates in the small oF the back - Dorsal + ventral roots join up = nerves -> some can branch: axons switch over to another nerve (interchange axons = plexus) - Big plexus at cervical region (serving arms); another plexus at lumbar cord (serving legs) 8 12 5 5 PSL302Y: Lecture 14, by ProF. MacKay Mon., Oct.18, 2010
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- Alignment: actual #ing of segments according to where roots exit at which vertebrae; that’s where vertebrae aligns w/ spinal segments - Sacral segments not aligned spatially w/ backbone, but actual root exiting are
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This note was uploaded on 03/27/2012 for the course PSL PSL300 taught by Professor Mackayfrench during the Fall '11 term at University of Toronto- Toronto.

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15 Neuroanatomy Overview - PSL302Y: Lecture 14, by Prof....

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