13. The Peripheral Nervous System

List the structural components of the peripheral nervous system, and describe the function of each component.

(a) Define plexus.

(b) Indicate the ventral rami of origin of the four major nerve plexuses.

Make a diagram of the hierarchy of motor control. Position the CPGs, motor cortex, brain stem nuclei, cerebellum, and basal nuclei in this scheme.

(a) Describe the formation and composition of a spinal nerve.

(b) Name the branches of a spinal nerve (other than the rami communicantes), and indicate their distribution.

Marcus, a football quarterback, suffered torn menisci in his right knee joint when tackled from the side. The same injury crushed his common fibular nerve against the head of the fibula. What locomotor problems did Marcus have after this?

As Luke fell off a ladder, he grabbed a tree branch with his right hand, but unfortunately lost his grip and fell heavily to the ground. Days later, Luke complained that his right upper limb was numb. What was damaged in his fall?

Mr. Frank, a former stroke victim who had made a remarkable recovery, suddenly began to have problems reading. He complained of seeing double and also had problems navigating steps. He was unable to move his left eye downward and laterally. Which cranial nerve was the site of lesion? (Right or left?)

Fumiko, a 19-year-old nursing student, had had a runny nose and sore throat for several days. Upon waking, her face felt “twisted.” When she examined her face in the mirror, she noticed that the right side looked “droopy” and she was unable to move the facial muscles on that side. This made it difficult to speak clearly or eat. Which cranial nerve was affected and on which side? What is a common cause of this condition?

Mr. Jake was admitted to the hospital with excruciating pain in his left shoulder and arm. He was found to have suffered a heart attack. Explain the phenomenon of referred pain as exhibited by Mr. Jake.

In 1962 a boy playing in a train yard fell under a train. The train wheel cleanly cut off his right arm. Surgeons reattached the arm, sewing nerves and vessels back together. The boy was told he should eventually regain the use of his arm but that it would never be strong enough to pitch a baseball. Explain why full recovery of strength was unlikely.

One of a group of rabbit hunters was accidentally sprayed with buckshot in both of his gluteal prominences. When his companions saw that he would survive, they laughed and joked about where he had been shot. They were horrified and ashamed a week later when they learned their friend would be permanently paralyzed and without sensation in both legs from the knee down, as well as on the back of his thighs. What had happened?