lecture 4c-spinal cord lesions

Question 1

what is a myotome

Answer 1

the skeletal musculature innervated by motor axons in a given spinal root

Question 2

what is a dermatone

Answer 2

the sensory component of each spinal nerve is distributed to a dermatome, a well defined segmental portion of the skin. conditions that affect the dorsal roots or dorsal root ganglia produce sensory alterations in the distribution of skin segments supplied by that

Question 3

what happens when you have total destruction to the cord at a certain level?

Answer 3

pts eventually lose all somatic sensations below the level of the lesion, and they also lose all voluntary motor control below the level of the lesion
-don’t lose involuntary

Question 4

what accounts for the paralysis everywerhe below the level of the lesion

Answer 4

UMN-corticospinal tract

-spastic paralysis: lose voluntary motor activity below the lesion, you don’t lose involuntary activity

Question 5

what spinal shock

Answer 5

happens right after the injury, early on

• the spinal cord shuts down for a few days-weeks
• during this time, you lose all motor-voluntary AND involuntary, so no reflexes, no muscle tone, no voluntary strength.

-AFTER THIS acute phase of spinal shock do the segmental reflexes and muscle tone return

Question 6

what happens above the level of the lesion?
at the level of the lesion?
below the level?

Answer 6

-normal

• motor: segmental LMN signs (ventral horns/verntral roots)-flaccid paralysis, fasciculations, atrophy, areflexia
• sensory: segmental loss of pain and temp (ventral white commissure) 1-2 lvls below
• motor: UMN signs (spastic paralysis, babinski, etc); paraplegia or tetraplegia
• sensory: no sensations

Question 7

what happens if you have a C1-C4 injury
injuries above C7?
injuries sparing of C7?
thoracolumbar injuries?

Answer 7

• rarely survive w/o immediate ventilatory support
• dependent on others for care
• retain elbow and wrist extension allowing independent ability to transfer to wheelchair
• have arm strength but require wheelchair

Question 8

what is brown-sequared syndrome aka hemicord syndrome or cord hemisection

Answer 8

lesion one half of the spinal cord at a certain level

Question 9

what happens to the white matter sections in cord hemisectoin

Answer 9

dorsal column: loss of proprioception, 2 point tactile, pressure, and vibratory sense. ipsilateral loss and below the level of the lesion

lateral corticospinal tract: UMN signs, ip loss, below level of lesion

spinothalamic tract: loss of pain and temp. contralateral loss. starting 1-2 segments below lvl of lesion

Question 10

what are the affects to the gray horn segments in a a hemisection

Answer 10

ventral horn gray: ipsi LMN signs. only at the level of the lesion (segmental loss)

dorsal horn gray: ipsi loss of pain and temp due ot damage to afferent fibers that have entered but not crossed. (no cell bodies for lissaurer’s to synapse on so can’t cross into ventral white comm)
-at segments located 1-2 lvls below (seg loss)