The OCULOMOTOR nerve (motor) controls most muscles that move the eyeball and some of those in the iris of the eye.
The TROCHLEAR nerve (motor) controls the muscles that turn the eyeball down and to the side.
The TRIGEMINAL nerve (sensory and some motor) is divided into three branches: ophthalmic, maxillary, and mandibular. It sometimes is called the great sensory nerve of the head because it supplies the sense of touch, pain, heat, and cold to the skin of the face, eyelids, cornea, conjunctival, tongue, teeth, and mucous membranes of the head. A branch of the mandibular division supplies motor fibers to the muscles of mastication.
The ABDUCENS nerve (motor) controls the muscles that turn the eye outward.
The FACIAL nerve (motor and sensory) control the muscles of the face, scalp, and ears. It contains autonomic motor fibers, which cause the salivary glands to secrete, and sensory fibers, which carry taste sensations from the anterior two-thirds of the tongue to the brain.
The GLOSSOPHARYNGEAL nerve (motor and sensory) carries sensation from the pharynx and posterior one-third of the tongue and transmits motor impulses to the parotid gland and to one of the small muscles of swallowing.
The VAGUS nerve (motor and some sensory) is composed of motor fibers (some of which are parasympathetic) and sensory fibers. It extends down through the neck to the pharynx, larynx, trachea, esophagus, and thoracic and abdominal viscera.
The ACCESSORY nerve (motor) supplies nerves to muscles of the neck (sternocleidomastoid, trapezius, pharyngeal, and laryngeal).
The HYPOGLOSSAL nerve (motor) controls the muscles of the tongue.
Figure 3-44.The peripheral nervous system.
Spinal nerves arise from the spinal cord and leave the vertebral canal in the spaces between the vertebrae. These nerves send fibers to sensory surfaces and all muscles of the trunk and extremities. Also, involuntary fibers go to the smooth muscles and glands of the gastrointestinal tract, urogenital system, and cardiovascular system. There are 31 pairs of spinal nerves: 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 1 coccygeal. The lower spinal nerves going to the legs and feet extend below the level of the spinal cord. The nerve roots arising from the lumbar and sacral regions pass some distance down the canal before making their exit. This bundle of nerve roots is called the cauda equina because it resembles a horses tail. The various roots emerge through openings in the sacrum and extend to the areas they supply.
Spinal nerves contain all types of sensory and motor fibers of both the voluntary and autonomic nervous systems. In some regions of the body they