Spinal Cord - Spinal Cord Functions of the Cord Conduction...

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Spinal Cord Functions of the Cord Conduction contains bundles of nerve fibers that conduct information up and down the cord Locomotion - control of repetitive coordinated contractions of several muscle groups in the limb consist of central pattern generators- CPG are neural circuits that produce self- sustaining patterns of behavior without sensory input (Examples: locomotion, respiration, mastication). Gross Anatomy extends from foramen magnum to L1 averages 1.8 cm thick and 45 cm long gives rise to 31 pairs of spinal nerves divided into cervical, thoracic, lumbar, and sacral regions Different Levels of Spinal Cord Control Cervical - neck, shoulder, outer arms, hand Thoracic -inner arm, chest, abdomen lumbar - front of leg and foot Sacra l- back of leg and foot Gross Anatomy cervical enlargement- (C3-T2) gives rise to nerves of the upper limb lumbar sacral enlargement (T9-T12)- give rise to nerves of the pelvic region and lower limbs Gross Anatomy medullary cone- taper of the distal cord cauda equina- bundle of nerves originating from the lumbar and sacral cord Terminal filum- fibrous continuation of the cord beyond the medullary cone consists of pia mater and neuroglial elements . s a vestige of the spinal cord of the embryonic tail , but in the adult it has no functional significance . Cauda Equina and Terminal Filum Cauda equina with conus medularis and terminal filum Cauda Equina Meninges of the Spinal Cord three fibrous membranes that encloses the cord dura mater- tough outer covering epidural space- between vetebrae and dura mater, contains blood vessels and adipose tissue subdural space- space between dura and arachnoid mater arachnoid mater subarchnoidl space- contains CSF
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pia mater- translucent membrane that close contours the cord and forms the terminal filum beyond the medullary cone Lumbar Puncture The needle is inserted between the arches of L3 and L4 . This avoids any damage to the spinal cord . Cross-Section: Gray Matter Cross-Section: Gray Matter The dorsal horn is a multi-layered structure. The thin outermost layer is called the posterior marginalis layer. The wide pale second layer is called the substantia gelatinosa , and the layer deep to that is called the nucleus proprius . Cross-Section: White Matter Spinal Tracts Columns consist of subdivisions called tracts or fasciculi ascending tracts- carry sensory info up the cord descending tracts- conduct motor impulses down the cord Decussation- crossover contralateral- when origin and destination are on opposite sides of the body ipsilateral- on same side Ascending Tracts Sensory signals typically travel across three neurons from origin to destination first order neuron- detects stimulus and transmits to cord second order neuron- relays form cord to thalamus in brain stem third order neuron- relays to sensory region of the cerebral cortex
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Spinal Cord - Spinal Cord Functions of the Cord Conduction...

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