Peripheral Nervous System and Reflex Activity

Peripheral Nervous System and Reflex Activity

After studying this chapter, readers should be able to:

1. Describe the peripheral nervous system and its components.

2. List the types of somatic and visceral sensory receptors.

3. Explain the three levels of the somatosensory system.

4. Name 12 cranial nerves.

5. Explain reflex activity and spinal reflexes.

6. List only the sensory cranial nerves.

7. Describe the three branches of the trigeminal cranial nerve.

8. Describe peripheral motor endings.

9. Explain the reflex arc.

10. Describe a somatic reflex.

Overview

The peripheral nervous system (PNS) consists of the peripheral nerves connecting the central nervous system (CNS) to other parts of the body. The PNS includes the cranial and spinal nerves and can be sub-divided into the somatic nervous system (SNS) and autonomic nervous system (ANS). The CNS and PNS work together, providing sensory, integrative, and motor functions to the body. The PNS is made up of all neural structures that are outside the brain and spinal cord. The SNS oversees conscious activi-ties, whereas the ANS oversees unconscious activities. The SNS consists of cranial and spinal nerve fibers connecting the CNS to the skin and skeletal muscles. The ANS includes fibers connecting the CNS to the visceral organs such as the heart, stomach, intestines, and glands. The PNS allows us to process information between our bodies and our environments. The CNS and PNS are shown in FIGURE 13-1.