Flashcards in Lab Section 4 Deck (59):
what is a radiculopathy?
damage to a spinal nerve, a dorsal root or a ventral root
what is a myotome and a dermatome?
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
what spinal segments contribute to the cervical plexus and what does it supply?
the muscles and skin of the neck
what spinal segments contribute to the brachial plexus and what does it supply?
muscles and skin of the arm
what spinal segments contribute to the lumbar plexus and what does it supply?
the inguinal region, the lower abdominal region and the anterior and middle compartments of the thigh
what spinal segments contribute to the sacral plexus and what does it supply?
the gluteal region, the posterior compartment of the thigh and the entire leg and foot
at what level does the spinal cord end? what does it continue as?
continues as the cauda equina
describe the divisions of the sciatic nerve.
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
what is the difference between a peripheral mononeuropathy and a plexopathy?
a peripheral neuropathy is of one peripheral nerve while a plexopathy may be more diffuse
under what conditions could an incomplete lesion of a peripheral nerve exist? what are the symptoms?
with a nerve entrapment
partial loss of sensation or pasesthesia and weakness of the muscles the nerve supplies
what would cause a radiculopathy and what is it associated with?
a herniated disc compressing the root
burning or tingling of the dermatome with reduced sensation and reduced strength of the muscle supplied by it
which disc herniations are most common?
C6, C7, L5 and S1 (lumbosacral far more common)
what test is helpful for diagnosis of nerve root compression in the lumbosacral region?
straight leg raising test or the crossed straight leg raising test because it results in traction of the nerve roots
decreased biceps reflex could be caused by which two radiculopathies? what differentiates them?
C5 and C6
C6 also has a decreased brachioradialis reflex
decreased triceps reflex is caused by which radiculopathy?
a decreased patellar reflex comes with which radiculopathies? what other symptom is common?
damage to L5 gives what positive sign?
The trendelenberg sign (patient lifts leg up and the hip sags)
loss of the achilles tendon reflex can point to which radiculopathy?
what type of information is contained within the cell bodies of the intermediate gray area?
a mixture of sensory and motor neurons
what type of axons carry epicritic information and where do they enter the dorsal cell column?
large myelinated axons that enter medially within the dorcal funiculus
which large myelinated axons synapse onto the dorsal horn?
axons that inhibit pain signals
what type of axons carry protopathic information and how do they travel up the spinal cord?
small un myelinated (or with little)
ascend or descend in Lissauer's tract a few segments and synapse on the dorsal horn contralaterally
which sensory neurons may project directly to motor neurons and why?
because they contain information about muscle length and tension to govern reflexes
what are reflexes mediated by?
what is a motor nucleus?
motor nuclei that are located over one or more spinal segments. all innervate the same muscle
which spinal levels contain the most gray matter?
what type of motor nuclei project to the limb muscles? what do the other motor nuclei do?
lateral motor nuclei
medial motor nuclei innervate axial muscles
what happens to the amount of white matter as you ascend the spinal cord?
it increases because of there are more axons from below
what other horn is associated with the thoracic spine? what does it contain?
the intermediolateral horn
contains cell bodies from the preganglionic sympathetic neurons
at what level can you find Clarke's nucleus and where is it located?
in the thoracic spine (T5 or 6)
located on the medial aspect of the dorsal horn close to the central canal of the spine
what are the three funiculi and where are they located?
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
damage to what two areas are necessary to eliminate epicritic sensation below a spinal level?
damage to the dorsal funiculus and the dorsal part of the lateral funiculus
the anterolateral system is made up of what kind of axons?
spinoreticular, spinotectal and spinothalamic axons carrying protopathic information
describe the touch information carried by the anterolateral system.
less discriminative (less discrete)
what is dissociated sensory loss?
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
what information is carried by the spinocerebellar system? what fasciculus first carries it?
at first are carried by the gracile and cuneate fasciculi
axons from clarke's nucleus gather into what? where do these axons end up going?
the dorsal spinocerebellar tract on the same side of the spine
end up going into the inferior cerebellar peduncle
where does proprioceptive information from the top of the body synapse? where do they go from there?
in the accessory cuneate nucleus in the medulla
from there, they go to the inferior cerebellar peduncle
what do corticospinal axons from the sensory cortex do and where do they synapse?
they modulate sensory input
synapse in the dorsal horn
what percentage of the corticospinal tract does not cross in the medulla? what does it turn into?
the ventral corticospinal tract (controling axial and proximal muscular movement to prepare for distal movement)
which brainstem-spinal tracts are involved with distal and which with proximal motor control?
vestibulospinal, tectospinal and reticulospinal- proximal
if paralysis is incomplete, which movements are more likely to survive and why?
axial and proximal limb movements because of more bilateral control from the tracts supporting them
what type of innervation is the hypothalamo-reticulo-spinal pathway responsible for? what is its pathway?
axons from the hypothalamus> medullary reticular formation > HRST in spinal cord > intermediolateral cell column
if a patient has Horner's Syndrome, where could the damage be?
in the cervical sympathetic galgia, in the HRST above T1, or in the hypothalamus or medullary reticular formation
why is there loss of muscle tone with sensory loss of a muscle?
because there is a disruption of spinal reflexes
why does muscle death occur rapidly after denervation? does this occur in UMN disease?
because motor neurons have a trophic effect on muscle
what is spinal shock?
when there is flaccid paralysis and hyporeflexia after an UMN injury (brain or spinal cord) immediately after injury. replaced by hypertonia and hyperreflexia
what white matter structures can be seen on the sacral level of the spinal cord?
the gracile fasciculus, Lissauer's Tract, the anterolateral system, the extrapyramidal tracts, the ventral corticospinal tract and the lateral corticospinal tract
explain the difference between the sacral and lumbar levels of the spinal cord.
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
what new structures can be found in the thoracic levels of the spinal cord?
intermediolateral horn and the HRST (sympathetic)
Dorsal Spinocerebellar tract, clarke's nucleus (proprioception)
cuneate fasciculus (epicritic)
describe the relationship between the cuneate and gracile fasciculus.
the cuneate is more lateral than the gracile fasciculus
what has gone away from the spinal cord when moving from the thoracic sections to the cervical portion?
the intermediolateral cell column and clarke's nucleus
in what cord areas does the HRST exist?
in the cervical and thoracic spinal cord
in what region does Lissauer's tract disappear?
in the rostral cervical spine
what structures appear for the first time in the rostral cervical spinal cord?
the spinal tract (transitioning into) and nucleus of CN V
what major positional changes appear from the transition from caudal to rostral cervical spine? why?
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
what does the dorsal horn turn into at the most caudal region of the cervical spine?
the spinal nucleus of V
describe the blood supply to the spinal cord
anterior spinal artery supplies the ventral 2/3 of the spinal cord while the posterior supplies the dorsal