Lab Section 4

Question 1

what is a radiculopathy?

Answer 1

damage to a spinal nerve, a dorsal root or a ventral root

Question 2

what is a myotome and a dermatome?

Answer 2

a myotome is all of the muscles supplied by a spinal nerve and a dermatome is all of the skin supplied by a spinal nerve

Question 3

what spinal segments contribute to the cervical plexus and what does it supply?

Answer 3

C1-4

the muscles and skin of the neck

Question 4

what spinal segments contribute to the brachial plexus and what does it supply?

Answer 4

C4-T1

muscles and skin of the arm

Question 5

what spinal segments contribute to the lumbar plexus and what does it supply?

Answer 5

L1-4

the inguinal region, the lower abdominal region and the anterior and middle compartments of the thigh

Question 6

what spinal segments contribute to the sacral plexus and what does it supply?

Answer 6

L4-S4

the gluteal region, the posterior compartment of the thigh and the entire leg and foot

Question 7

at what level does the spinal cord end? what does it continue as?

Answer 7

at L1

continues as the cauda equina

Question 8

describe the divisions of the sciatic nerve.

Answer 8

sciatic nerve innervates the hamstrings before dividing into the tibial and common fibular nerves
the common fibular divides into the superficial and deep fibular nerves

Question 9

what is the difference between a peripheral mononeuropathy and a plexopathy?

Answer 9

a peripheral neuropathy is of one peripheral nerve while a plexopathy may be more diffuse

Question 10

under what conditions could an incomplete lesion of a peripheral nerve exist? what are the symptoms?

Answer 10

with a nerve entrapment

partial loss of sensation or pasesthesia and weakness of the muscles the nerve supplies

Question 11

what would cause a radiculopathy and what is it associated with?

Answer 11

a herniated disc compressing the root

burning or tingling of the dermatome with reduced sensation and reduced strength of the muscle supplied by it

Question 12

which disc herniations are most common?

Answer 12

C6, C7, L5 and S1 (lumbosacral far more common)

Question 13

what test is helpful for diagnosis of nerve root compression in the lumbosacral region?

Answer 13

straight leg raising test or the crossed straight leg raising test because it results in traction of the nerve roots

Question 14

decreased biceps reflex could be caused by which two radiculopathies? what differentiates them?

Answer 14

C5 and C6

C6 also has a decreased brachioradialis reflex

Question 15

decreased triceps reflex is caused by which radiculopathy?

Answer 15

C7

Question 16

a decreased patellar reflex comes with which radiculopathies? what other symptom is common?

Answer 16

L2-3

waddling gait

Question 17

damage to L5 gives what positive sign?

Answer 17

The trendelenberg sign (patient lifts leg up and the hip sags)

Question 18

loss of the achilles tendon reflex can point to which radiculopathy?

Answer 18

S1

Question 19

what type of information is contained within the cell bodies of the intermediate gray area?

Answer 19

a mixture of sensory and motor neurons

Question 20

what type of axons carry epicritic information and where do they enter the dorsal cell column?

Answer 20

large myelinated axons that enter medially within the dorcal funiculus

Question 21

which large myelinated axons synapse onto the dorsal horn?

Answer 21

axons that inhibit pain signals

Question 22

what type of axons carry protopathic information and how do they travel up the spinal cord?

Answer 22

small un myelinated (or with little)

ascend or descend in Lissauer’s tract a few segments and synapse on the dorsal horn contralaterally

Question 23

which sensory neurons may project directly to motor neurons and why?

Answer 23

proprioceptive

because they contain information about muscle length and tension to govern reflexes

Question 24

what are reflexes mediated by?

Answer 24

interneurons

Question 25

what is a motor nucleus?

Answer 25

motor nuclei that are located over one or more spinal segments. all innervate the same muscle

Question 26

which spinal levels contain the most gray matter?

Answer 26

C5-T1 (arm) | L3-S2 (leg)

Question 27

what type of motor nuclei project to the limb muscles? what do the other motor nuclei do?

Answer 27

lateral motor nuclei | medial motor nuclei innervate axial muscles

Question 28

what happens to the amount of white matter as you ascend the spinal cord?

Answer 28

it increases because of there are more axons from below

Question 29

what other horn is associated with the thoracic spine? what does it contain?

Answer 29

the intermediolateral horn | contains cell bodies from the preganglionic sympathetic neurons

Question 30

at what level can you find Clarke's nucleus and where is it located?

Answer 30

in the thoracic spine (T5 or 6) | located on the medial aspect of the dorsal horn close to the central canal of the spine

Question 31

what are the three funiculi and where are they located?

Answer 31

dorsal- between the two dorsal horns lateral- lateral to the gray matter (between the ventral and dorsal roots) anterior- anterior to the two ventral roots

Question 32

damage to what two areas are necessary to eliminate epicritic sensation below a spinal level?

Answer 32

damage to the dorsal funiculus and the dorsal part of the lateral funiculus

Question 33

the anterolateral system is made up of what kind of axons?

Answer 33

spinoreticular, spinotectal and spinothalamic axons carrying protopathic information

Question 34

describe the touch information carried by the anterolateral system.

Answer 34

less discriminative (less discrete)

Question 35

what is dissociated sensory loss?

Answer 35

as a result of damage to the spinal cord, it is loss of sensation on one side of the body paired with loss of protopathic sensation on the other side of the body

Question 36

what information is carried by the spinocerebellar system? what fasciculus first carries it?

Answer 36

proprioceptive | at first are carried by the gracile and cuneate fasciculi

Question 37

axons from clarke's nucleus gather into what? where do these axons end up going?

Answer 37

the dorsal spinocerebellar tract on the same side of the spine end up going into the inferior cerebellar peduncle

Question 38

where does proprioceptive information from the top of the body synapse? where do they go from there?

Answer 38

in the accessory cuneate nucleus in the medulla | from there, they go to the inferior cerebellar peduncle

Question 39

what do corticospinal axons from the sensory cortex do and where do they synapse?

Answer 39

they modulate sensory input | synapse in the dorsal horn

Question 40

what percentage of the corticospinal tract does not cross in the medulla? what does it turn into?

Answer 40

10% | the ventral corticospinal tract (controling axial and proximal muscular movement to prepare for distal movement)

Question 41

which brainstem-spinal tracts are involved with distal and which with proximal motor control?

Answer 41

rubrospinal- distal | vestibulospinal, tectospinal and reticulospinal- proximal

Question 42

if paralysis is incomplete, which movements are more likely to survive and why?

Answer 42

axial and proximal limb movements because of more bilateral control from the tracts supporting them

Question 43

what type of innervation is the hypothalamo-reticulo-spinal pathway responsible for? what is its pathway?

Answer 43

sympathetic | axons from the hypothalamus> medullary reticular formation > HRST in spinal cord > intermediolateral cell column

Question 44

if a patient has Horner's Syndrome, where could the damage be?

Answer 44

in the cervical sympathetic galgia, in the HRST above T1, or in the hypothalamus or medullary reticular formation

Question 45

why is there loss of muscle tone with sensory loss of a muscle?

Answer 45

because there is a disruption of spinal reflexes

Question 46

why does muscle death occur rapidly after denervation? does this occur in UMN disease?

Answer 46

because motor neurons have a trophic effect on muscle | no

Question 47

what is spinal shock?

Answer 47

when there is flaccid paralysis and hyporeflexia after an UMN injury (brain or spinal cord) immediately after injury. replaced by hypertonia and hyperreflexia

Question 48

what white matter structures can be seen on the sacral level of the spinal cord?

Answer 48

the gracile fasciculus, Lissauer's Tract, the anterolateral system, the extrapyramidal tracts, the ventral corticospinal tract and the lateral corticospinal tract

Question 49

explain the difference between the sacral and lumbar levels of the spinal cord.

Answer 49

the dorsal and ventral horns (especially ventral) are widened due to the extra cell bodies for the lower limbs there is now the rubrospinal tract nestled into the lateral corticospinal tract anteriorly

Question 50

what new structures can be found in the thoracic levels of the spinal cord?

Answer 50

``` intermediolateral horn and the HRST (sympathetic) Dorsal Spinocerebellar tract, clarke's nucleus (proprioception) cuneate fasciculus (epicritic) ```

Question 51

describe the relationship between the cuneate and gracile fasciculus.

Answer 51

the cuneate is more lateral than the gracile fasciculus

Question 52

what has gone away from the spinal cord when moving from the thoracic sections to the cervical portion?

Answer 52

the intermediolateral cell column and clarke's nucleus

Question 53

in what cord areas does the HRST exist?

Answer 53

in the cervical and thoracic spinal cord

Question 54

in what region does Lissauer's tract disappear?

Answer 54

in the rostral cervical spine

Question 55

what structures appear for the first time in the rostral cervical spinal cord?

Answer 55

the spinal tract (transitioning into) and nucleus of CN V

Question 56

what major positional changes appear from the transition from caudal to rostral cervical spine? why?

Answer 56

the lateral corticospinal tract has switched places with the HRST in the nook between the dorsal and ventral horns this is because the LCST is coming from the medial deccusation of the pyramids

Question 57

what does the dorsal horn turn into at the most caudal region of the cervical spine?

Answer 57

the spinal nucleus of V

Question 58

describe the blood supply to the spinal cord

Answer 58

anterior spinal artery supplies the ventral 2/3 of the spinal cord while the posterior supplies the dorsal

Question 59

if there is a clot in the anterior spinal artery in the spine, what are the symptoms?

Answer 59

paralysis and loss of protopathic sensation below the occlusion