1. In the PNS, the cell bodies of neurons are concentrated in massescalled _______________.

2. The fibrous sheath around a nerve is called the _______________.

3. The 12 pairs of nerves that arise from the brainstem are calledthe _______________.

4. Eye movements are controlled by the oculomotor, _______________, and __________________ nerves.

5. The muscles of facial expression are controlled mainly by the _______________ nerve.

6. One cranial nerve, the _______________, has a far-reaching course that innervates many viscera ofthe thoracic and abdominal cavities.

7. Except in the thoracic region, the spinal nerves branch andrejoin each other extensively to form _______________.

8. The axillary, radial, and ulnar nerves arise from the _______________ plexus.

9. Of the motor nerve fibers leading to a skeletal muscle, the _______________ neurons innervate the intrafusal fibers of themuscle spindles and the _______________ neuronsinnervate the extrafusal fibers that form most of the muscle.

10. A _______________ reflex arc is one with no interneuron and a minimum ofsynaptic delay. Such an arc is involved in the patellar tendon reflex, for example.

11. When a flexor muscle responds reflexively, contraction of itsantagonist must be suppressed. This is called _______________.

12. The _______________ has sympathetic and parasympathetic divisions.

13. Two nerve branches called _______________ connect each sympatheticganglion to a spinal nerve.

14. The efferent pathways of the sympathetic nervous system have ashort _______________ fiber and long_______________ fiber.

15. The two types of receptors for acetylcholine are _______________ receptors, found at the neuromuscular junctions, and_______________ receptors, found on most parasympathetic target cells.

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