The OCULOMOTOR nerve (motor) con-
trols 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 divi-
sion supplies motor fibers to the muscles
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 sen-
sations from the anterior two-thirds of the
tongue to the brain.
The ACOUSTIC (vestibulocochlear) nerve
(sensory) is the nerve of hearing and
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 sen-
sory) 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
The ACCESSORY nerve (motor) supplies
nerves to muscles of the neck (ster-
nocleidomastoid, trapezius, pharyngeal,
. The HYPOGLOSSAL nerve (motor) con-
trols the muscles of the tongue.
Spinal nerves arise from the spinal cord and
leave the vertebral canal in the spaces between the
vertebrae. These nerves send fibers to sensory sur-
faces 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
Figure 3-44.The peripheral nervous system.