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PART 3 Integration and Control Systems

are responsible for regulating the sensitivity of the musclea. Alpha motor neurons d. Golgi tendon organsb. Sensory neurons e. Inhibitory interneuronsc. Gamma motor neurons

11. A dermatomea. is the area of skin supplied by a pair of spinal nerves.b. exists for each spinal nerve except C1.c. can be used to locate the site of spinal cord or nerve root damage.d. All of these are correct.

12. Which of these nerves arises from the cervical plexus?a. median c. phrenic e. ulnarb. musculocutaneous d. obturator

13. The skin on the posterior surface of the hand is supplied by thea. median nerve. c. ulnar nerve. e. radial nerve.b. musculocutaneous nerve. d. axillary nerve.

14. The sciatic nerve is actually two nerves combined within the samesheath. The two nerves are thea. femoral and obturator.b. femoral and gluteal.c. common fibular (peroneal) and tibial.d. common fibular (peroneal) and obturator.e. tibial and gluteal.

15. The muscles of the anterior compartment of the thigh are supplied by thea. obturator nerve. d. femoral nerve.b. gluteal nerve. e. ilioinguinal nerve.c. sciatic nerve.

Answers in appendix E

8. Which of these events occurs when a person steps on a tack with theright foot?a. The right foot is pulled away from the tack because of the Golgitendon reflex.b. The left leg is extended to support the body because of the stretchreflex.c. The flexor muscles of the right thigh contract, and the extensormuscles of the right thigh relax because of reciprocal innervation.d. Extensor muscles contract in both thighs because of the crossedextensor reflex.

9. Damage to the dorsal ramus of a spinal nerve results ina. loss of sensation. c. Both a and b are correct.b. loss of motor function.

10. A collection of spinal nerves that join together after leaving the spinalcord is called aa. ganglion. c. projection nerve.b. nucleus. d. plexus.

1. Describe how stimulation of a neuron that has its cell body in thecerebrum can inhibit a reflex that is integrated within the spinal cord.

2. A cancer patient has his left lung removed. To reduce the spaceremaining where the lung is removed, the diaphragm on the left sideis paralyzed to allow the abdominal viscera to push the diaphragmupward. What nerve is cut? Where is a good place to cut it, and whenwould the surgery be done?

3. During a difficult delivery, the baby’s arm delivered first. The attendingphysician grasped the arm and forcefully pulled it. Later, a nurseobserved that the baby could not abduct or adduct the medial four fin-gers, and flexion of the wrist was impaired. What nerve was damaged?

4. Two patients are admitted to the hospital. According to their charts,both have herniated disks that are placing pressure on the roots of thesciatic nerve. One patient has pain in the buttocks and the posterioraspect of the thigh. The other patient experiences pain in the posteriorand lateral aspects of the leg and the lateral part of the ankle and foot.Explain how the same condition, a herniated disk, can produce suchdifferent symptoms.

5. In an automobile accident, a woman suffers a crushing hip injury. Foreach of the following conditions, state what nerve is damaged.

a.b.c.d.e.

unable to adduct the thighunable to extend the kneeunable to flex the kneeloss of sensation from the skin of the anterior thighloss of sensation from the skin of the medial thigh

6. A skier breaks his ankle. As part of his treatment, the ankle and legare placed in a plaster cast. Unfortunately, the cast is too tight aroundthe proximal portion of the leg and presses in against the neck of thefibula. Predict where the patient will experience tingling or numbnessin the leg. Explain.

7. Cecil’s motorcycle collided with a tree. When the ambulance arrived,he complained of loss of sensation and voluntary movement in hislower limbs, as well as impaired mobility in his upper limbs, especiallyhis hands. Examination revealed that the accident had permanentlydamaged his spinal cord. Cecil was able to breathe on his own and,with exercise, movement of his upper limbs eventually improved,although the mobility of his hands was still impaired, and he neverregained the use of his lower limbs. At which level was Cecil’s spinalcord injured? Explain how you were able to determine your answer.

Answers in appendix F