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Lecture 10

Week/Lecture 10: Spinal Cord.pdf

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Humber College
BIOL 171

Spinal Cord conducts sensory impulses from body to brain conducts motor impulses from brain to body controls reflex activities Spinal Cord Protection epidural space (filled with fat) cushions spinal cord inside bones to restrict movement meninges (membranes surrounding the brain and spinal cord) triple layer protection dura mater subdural space (deep to dura mater) filled with interstitial fluid arachnoid mater (deep to dura mater) subarachnoid space (deep to arachnoid mater) filled with CSF (cerebral spinal fluid) pia mater follows contours of brain Spinal Cord flattened cylinder 42-45 cm long, 2 cm diameter lies within the spinal canal extends from foramen magnum (hold in base of skull to allow spinal cord to connect to brain) to L4 in newborn, L1 in adult growth of cord stops at age 5 cervical enlargement: area of spinal cord that is slightly thicker b/c of more nerve tissue lumbar enlargement: area of spinal cord that is slightly thicker b/c of more nerve tissue leaving spinal cord conus medullaris cone-shaped end of spinal cord cauda equine dorsal, ventral roots of lowest spinal nerves branching nerves *tail film terminal thread-like extension of pia mater stabilizes spinal cord in spinal canal gray matter unmyelinated (cell bodies, dendrites, axon terminals, some axons) shaped like butterfly (or H) divided into horns dorsal horn somatic, autonomic nuclei one on either side sensory axons ventral horn cell bodies of LMN (lower motor neurons) one on either side lateral horn only in thoracic spinal cord autonomic motor cell bodies gray commissure area in centre where horns connect white matter myelinated (long axons) surrounds gray matter divided into columns (funiculi) lateral columns dorsal column ventral column contains sensory and motor nerve tracts posterior median sulcus (shallow) anterior median fissure (deep) central canal hole running down middle of spinal cord w/CSF Spinal Cord and Spinal Nerves spinal nerves emerge from SC as roots dorsal root contains sensory fibres ventral root contains motor fibres dorsal root ganglion (DRG) ganglion: group of cell bodies contains cell bodies of sensory neurons (coming from dorsal root) Tracts of the Spinal Cord highways for sensory and motor information (sensory tracts ascend, motor tracts descend) name indicates position in SC and (usually) direction of signal ex: anterior spinothalamic tract anterior part of SC impulses travel from SC to thalamus sensory tract Spinal Tracts (**know slides) **motor tracts pyramidal (corticospinal): direct pathways precise, voluntary movements (writing, etc) extrapyramidal tracts: indirect pathways "programmed" automatic movements (swinging arms while walking) coordinate gross movements and visual reflexes (catch a ball) (many different paths: see slide 21) **sensory tracts dorsal columns proprioception (knowing where body parts are at any point in time), discriminative touch (recognizing an object just by touch—reaching into a bag), two-point discrimination (pencil experiment: moving away from eachother), pressure, vibration spinothalamic pain, temperature, deep pressure, crude touch (knowing broad feelings: rough, smoot
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