Spinal Cord

Front 1

central canal

Back 1

filled with CSF and lined with ependymal cells

Front 2

gray matter

Back 2

region of neuronal and glial cell bodies that surrounds the ependymal layer, shaped like a butterfly or the letter H

Front 3

dorsal horn

Back 3

forms the upper arm of the H

contains interneurons and the central terminations of sensory afferent fibers (enter through the dorsal roots)

Front 4

ventral horn

Back 4

forms the lower arm of the H

contains interneurons and the somatic motor neurons (innervate skeletal muscle via exiting axons in the ventral roots)

Front 5

intermediate zone

Back 5

between the dorsal and ventral horn, extends laterally as the lateral horn

contain interneurons and visceral motoneurons associated with autonomic function

Front 6

lateral horn

Back 6

lateral extension of the intermediate zone, only visible in the thoracolumbar cord

Front 7

central gray

Back 7

surrounds the central canal containing the dorsal and ventral gray commissures

contain interneurons and visceral motoneurons associated with autonomic function

Front 8

white matter

Back 8

Surrounds the grey area and contains myelinated and unmyelinated axons (very few neuronal cell bodies) of ascending and descending nerve fibers

Divided into dorsal, lateral, and ventral funiculus
Amount increased from caudal to cranial

Front 9

funiculus

Back 9

"rope-like"

Front 10

dorsal root entry zone

Back 10

edges of the dorsal horn through which the bundles of dorsal root sensory axons enter the cord

Front 11

ventral root

Back 11

motor axons exit the cord at the bottom (ventrolateral aspect) of the ventral horn

Front 12

number of cervical, thoracic, lumbar, sacral, and caudal spinal cord segments

Back 12

8, 13, 7, 3, ~5

Cervical region has one more spinal cord segment than cervical vertebrae because the spinal cod and vertebral column grow at different rates after birth, spinal cord also ends quite cranial to the sacrum

Front 13

conus medullaris

Back 13

termination of spinal cord

dogs at L6/L7

Front 14

cauda equina

Back 14

"horse's tail"

Spinal nerves that descend caudal to the conus modulars and contain only the dorsal and ventral roots

Front 15

cervical (or brachial) enlargement

Back 15

extends from spinal segments C7 to T2 and is the site of exit of the spinal nerves of the brachial plexus which innervate the forelimbs

Front 16

lumbar enlargement

Back 16

extends from spinal segments L4 to S1 and is the exit point of nerves of the lumbosacral plexus, which supplies the hindlimbs

Front 17

lumbosacral plexus

Back 17

supplies the hind limbs

Front 18

Destinations of sensory primary afferent fibers

Back 18

Local spinal reflex interneurons
2nd order interneurons projecting cranially to a supraspinal site
Propriospinal interneurons projecting cranially or caudally to other spinal cord segments
Monosynaptic to lower motor neurons

Front 19

Motor neuron destinations

Back 19

Send axons out through ventral roots, into spinal/peripheral nerve, and innervate a skeletal muscle at a neuromuscular junction
Cell bodies for each muscle grouped in motor neuron pool that spans several segments

Front 20

dermatome

Back 20

the skin ("derma") area innervated by one segment of the spinal cord

includes one spinal nerve and all of its peripheral nerve branches

Front 21

second order interneurons

Back 21

project an axon cranially through an ascending "pathway" to a supra spinal site

Front 22

propriospinal interneruons

Back 22

which project axons cranially or caudally to other spinal cord segments

Front 23

lower motor neurons

Back 23

Utilized when only going to spinal cord

Front 24

upper motor neurons

Back 24

Utilized when under command of the brain

Front 25

divergence

Back 25

One presynaptic neuron may have connections with multiple postsynaptic neurons or multiple connections with one postsynaptic neuron

Front 26

convergence

Back 26

One postsynaptic neuron may receive connections from many presynaptic neurons

Front 27

withdrawl reflex

Back 27

Nociception

occurs all in the spinal cord, doesn't need the brain

Front 28

pain response

Back 28

Requires intact cerebral cortex

Front 29

nociceptors

Back 29

pain receptors

Front 30

injury to brachial enlargement

Back 30

Forelimbs: paralysis, areflexia, atonia, denervation atrophy, sensory disturbance

Hindlimbs: paralysis, hyperreflexia, hypertonia, disuse atrophy, sensory disturbance

Front 31

injury to thoracolumbar region

Back 31

Forelimbs: mostly normal plus Schiff-Sherrington (increase extension of forelimb)

Hindlimbs: paralysis, hyperreflexia, hypertonia, disuse atrophy, sensory disturbance

Front 32

injury to lumbosacral region

Back 32

Forelimbs: normal

Hindlimbs: Paralysis, areflexia, atonia, denervation atrophy, sensory disturbance

Front 33

cutaneous trunci reflex

Back 33

Lesion location determination

skin twitch

Front 34

cutaneous areas

Back 34

Smaller than dermatomes

name given to a particular peripheral nerve

Front 35

Major of info sent to CNS from sensory afferents is either:

Back 35

Not perceived at that moment because of cortical pathway inhibition

OR

Can never perceived because a pathway to the cortex doesn't exist