13. The Peripheral Nervous System

Complaining of muscle weakness, Delia goes to the doctor. Devise a series of physical examination tests that would help to determine if her problem involves upper or lower motor neurons.

Which of the following structures is not part of the central nervous system?

a. The brain

b. A nerve

c. The spinal cord

d. A tract

Explain both the structural and functional classifications of the nervous system. In your explanation, include the subdivisions of each.

a. What is myelin?

b. How does the myelination process differ in the CNS and PNS?

Which two types of neuroglia insulate neuron cell bodies and axons in the PNS from their surroundings?

Destruction of the ventral horn cells of the spinal cord results in loss of

a. Integrating impulses

b. Sensory impulses

c. Voluntary motor impulses

d. All of these

Which cranial nerves are (a) sensory only, (b) primarily motor, and (c) mixed?

Mary complains that when she wakes up in the morning, her thumb and forefinger are always “asleep.” She mentions this condition to her physician, who asks Mary whether she sleeps with her wrists flexed. She replies that she does. The physician tells Mary that sleeping in that position may compress a portion of one of her peripheral nerves, producing her symptoms. Which nerve is involved?

What is the functional relationship of the peripheral nervous system to the central nervous system?

Explain why damage to peripheral nerve fibers is often reversible, whereas damage to CNS fibers rarely is.