Study Questions
The muscles of the posterior aspect of the thigh, or hamstring musculature, are responsible for flexing the knee joint. Beginning with the motor neuron cell bodies in the gray matter of the spinal cord, identify the most likely pathway that axons would travel from the spinal cord to the hamstring muscles?
F. Dorsal horn, dorsal root, dorsal ramus
Answer
The correct answer is E. You answered E.
All skin of the back is segmentally innervated by the dorsal rami branches of spinal nerves. Sensory information is then conducted through the dorsal root into the dorsal horn of the gray mater of the spinal cord.
A 50-year-old man is diagnosed with flaccid paralysis limited to the right arm, without pain or paresthesias. No sensory deficits are noted. Laboratory studies reveal that the patient is infected with West Nile virus. The target that the virus has infected resulting in this patient's symptoms is most likely the
Ventral horn of spinal cord gray matter
Ventral rami of spinal nerves
Dorsal horn of spinal cord gray matter
Dorsal rami of spinal nerves
The correct answer is A.
The patient has no sensory deficits and presents with only motor deficits. Therefore, the virus affects the ventral horn of the gray matter because that is the location of the motor neuron cell bodies.
A 48-year-old man goes to his physician because of pain and paresthesia along the lateral aspect of the leg and the dorsum of the foot. The patient's symptoms suggest impingement of the L5 spinal nerve resulting from a herniated intervertebral disc. The L5 spinal nerve most likely exits between which of the following vertebrae?
L3–L4 vertebrae
L4–L5 vertebrae
L5–S1 vertebrae
S1–S2 vertebrae
The correct answer is C.
Spinal nerves in the thoracic and lumbar vertebral region exit the vertebral canal below their associated vertebra. Therefore, the L5 spinal nerve exits below L5, between L5 and S1.
1. A 48-year-old man goes to his physician because of pain and paresthesia along the lateral aspect of the leg and the dorsum of the foot. The patient's symptoms suggest impingement of the L5 spinal nerve resulting from a herniated intervertebral disc. The L5 spinal nerve most likely exits between which of the following vertebrae?
The correct answer is C.
Spinal nerves in the thoracic and lumbar vertebral region exit the vertebral canal below their associated vertebra. Therefore, the L5 spinal nerve exits below L5, between L5 and S1.