Question 1

A patient presents with paralysis of the diaphragm and requires mechanical ventilation. Which spinal nerves are most likely damaged, and what is the name of the nerve involved?

Accepted Answer

C\_3–C\_5; phrenic nerve

Question 2

Which of the following best describes the difference between a root and a ramus of a spinal nerve?

Accepted Answer

A root is medial and carries only sensory or only motor fibers, while a ramus is distal and carries both sensory and motor fibers.

Question 3

A football player suffers a blow to the top of the shoulder, resulting in an inability to abduct the arm and loss of sensation over the shoulder. Which nerve is most likely injured?

Accepted Answer

Axillary nerve

Question 4

Which of the following statements about the brachial plexus is correct?

Accepted Answer

It is responsible for innervating the upper limb.

Question 5

A patient is unable to flex the wrist and has sensory loss on the medial side of the hand. Which nerve is most likely affected?

Accepted Answer

Ulnar nerve

Question 6

Which nerve is most likely to be compressed in carpal tunnel syndrome, leading to difficulty with thumb opposition?

Accepted Answer

Median nerve

Question 7

A patient presents with 'wrist drop' and inability to extend the hand at the wrist. Which nerve is most likely injured?

Accepted Answer

Radial nerve

Question 8

Which of the following best explains why damage to a single spinal nerve does not usually result in complete numbness of a dermatome?

Accepted Answer

Most dermatomes overlap, so destruction of a single spinal nerve will not cause complete numbness.

Question 9

A patient has pain radiating down the posterior thigh and leg, and foot drop. Which nerve is most likely involved, and what is the likely cause?

Accepted Answer

Sciatic nerve; herniated disc or trauma

Question 10

Which of the following is true regarding the formation of nerve plexuses?

Accepted Answer

Only ventral rami (except T\_2–T\_{12}) form plexuses.

Question 11

A patient is unable to extend the knee and has numbness over the anterior thigh. Which nerve and plexus are most likely affected?

Accepted Answer

Femoral nerve; lumbar plexus

Question 12

Which of the following best describes Hilton's law?

Accepted Answer

Any nerve serving a muscle that produces movement at a joint also innervates the joint and the skin over it.

Question 13

Which nerve is the longest and thickest in the body, and what muscles does it primarily innervate?

Accepted Answer

Sciatic nerve; hamstrings and most muscles of the leg and foot

Question 14

A patient has difficulty abducting the thigh and numbness in the medial thigh after pelvic surgery. Which nerve is most likely damaged?

Accepted Answer

Obturator nerve

Question 15

Which of the following is true regarding the ventral rami of T\_2–T\_{12}?

Accepted Answer

They form intercostal nerves that supply the thorax and abdominal wall.

Question 16

A patient presents with loss of sensation in the skin over the lateral forearm and weakness in elbow flexion. Which nerve is most likely affected?

Accepted Answer

Musculocutaneous nerve

Question 17

If the dorsal root of a spinal nerve is severed, what would be the functional consequence?

Accepted Answer

Loss of sensory function from the area innervated by that nerve

Question 18

Which of the following best explains why each limb muscle is innervated by more than one spinal nerve?

Accepted Answer

Because fibers from different ventral rami crisscross in plexuses

Question 19

A patient experiences tingling in the little finger after hitting the 'funny bone.' Which nerve is involved, and where is it most vulnerable?

Accepted Answer

Ulnar nerve; medial epicondyle of the humerus

Question 20

Which of the following equations best represents the number of pairs of spinal nerves in the human body?

Accepted Answer

$$8 + 12 + 5 + 5 + 1 = 31$$

Peripheral Nervous System: Spinal Nerves – Structure, Function, and Organization

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