See Table 13.2 and Figure 13.4
I. Olfactory - sensory nerves for smell. These nerves arise in the olfactory receptors of the nasal
epithelium and pass through holes in the cribriform plate to reach the olfactory bulb on the ventral
brain surface. The olfactory tracts lead from these bulbs back to the thalamus and then to the
frontal lobe for smell perception.
II. Optic - sensory only for vision. These fibers arise from the retina at the optic disk and travel
to the optic chiasma where half of them crossover. From there the optic tracts take impulses to
the thalamus which relays them to the visual cortex in the occipital lobe and visual reflex center in
the midbrain.
III Oculomotor * - motor to the extrinsic and intrinsic eye muscles (except superior oblique
and lateral rectus). Its parasympathetic fibers control muscles of the iris (for constricting the
pupil) and the ciliary disk, for accommodation of the lens for near vision.
IV Trochlear - controls the superior oblique muscle of the eye. Called the trochlear because the
tendon of this muscle passes through a pulley-shaped process called a trochlea. See
[superior view
of dissected eye].
V Trigeminal - Sometimes called the 'great sensory nerve of the face' this is the largest of the
cranial nerves. It has three branches, the ophthalmic, maxillary, and mandibular. From these it
receives sensations of a conscious nature, and controls the muscles for chewing.
VI Abducens - Its name says what this nerve effects - abduction of the eye. It controls the lateral
rectus muscle. See [lateral view of dissected eye].
VII Facial *- The chief motor nerve of the face, to muscles of facial expression, and
parasympathetic to lacrimal and salivary glands. Sensory for taste from the anterior two-thirds of
tongue.
VIII Acoustic or Auditory or Statoacoustic or Vestibulocochlear - this is the nerve bringing
stimuli from the inner ear for perception of hearing and balance.
IX Glossopharyngeal * - Motor to the muscles for swallowing and parasympathetic to the
parotid gland. Sensory from taste buds on the posterior tongue and other areas, as well as other
conscious sensations. It is also important in the sensory pathways for control of blood pressure and
respiration.
X Vagus * - The parasympathetic nerve to the viscera. Its fibers send stimuli to the heart,
stomach, intestines, bronchi, and virtually every other parasympathetic effector between the head
and the pelvis. The vagus also provides sensory input for cardiac and
respiration. But the muscles of respiration are voluntary and respiration itself is NOT
an autonomic
function.
XI Spinal Accessory - Runs together with spinal nerves to the sternocleidomastoid and trapezius
muscles.
XII Hypoglossal - Motor to the muscles of swallowing.