UCI BioSci D170, Williams Peripheral Nervous System (PNS)
Reading: Chapter 14
Describe the structures of the peripheral nervous system.
Sensory receptors – receptors that pick up stimuli and then initiate impulses into the
sensory axons, which carry the impulse into the CNS.
Nerves – bundles of peripheral axons. Will focus on cranial and spinal nerves, and their
somatic function.
Ganglia – clusters of peripheral cell bodies.
Motor endings – terminal boutons of motor neurons that innervate the effector organs,
muscles, and glands.
(We are skipping the peripheral sensory receptors section for now)
How many pairs of cranial nerves are there? How are they numbered? Are cranial nerves
sensory, motor, or both?
There are 12 pairs of cranial nerves that attach to the brain and pass through various
skull foramina. They are numbered from I to XII from the rostral to caudal direction.
Cranial nerves can be both sensory and motor.
What is a mnemonic device that can help you remember their order?
Oh, Oh, Oh, To Touch And Feel Very Good Velvet, AH!
Where are the cell bodies of cranial nerves found?
The cell bodies of sensory neurons lie in receptor organs or the cranial sensory ganglia.
The cell bodies of cranial motor neurons lie in the cranial nerve nuclei in the ventral gray
matter of the brain stem.
What are the three functional groups of cranial nerves? What types of sensory and motor
nerves are they?
1. Primarily or exclusively sensory fibers that contain special sensory fibers for
smell (I), vision (II) and hearing/equilibrium (VII).
2. Primarily motor nerves that contain somatic motor fibers to skeletal muscles of
the eye, neck, and tongue. III, IV, VI, XI, XII.
3. Mixed nerves that supply sensory innervation to the face, mouth, and viscera.
They also innervate the pharyngeal arch muscles and muscles of facial
expression. V, VII, IX, X.
Here is a useful mnemonic to help you remember whether the cranial nerves are sensory,
motor, or both: Some say marry money, but my brother says big business makes money.
Fill out this table regarding the cranial nerves. The sensory and motor type refer to SS (Somatic
Sensory), VS (Visceral Sensory), VM (Visceral Motor), or SM (Somatic Motor). This information
is what you should know about cranial nerves for this course.
*Exits thru the jugular foramen.
Sen Mot
Nerve sory Sensory function or Motor function Origin (simple)
type type
Olfactory
receptor cells
Olfactory (I)
VS Sense of smell in epithelium of
the nasal
cavity.
Optic (II) Retina of the
SS Vision
eye.
, UCI BioSci D170, Williams Peripheral Nervous System (PNS)
“Directs SM
axons…”
Innervate “Transmits
muscles that <- visceromotor Oculomotor
Oculomotor
direct the SM neurons...” nuclei in the
(III)
eyeball: superior, VM Constrict the ventral
medial, and -> pupil, alters lens midbrain.
inferior rectus, shape for vision.
and inferior
oblique muscle.
Innervates the
superior oblique Trochlear
Trochlear (IV) muscle nuclei in the
SM
(downward and dorsal
outward midbrain.
movement).
Sensory
receptors in
Trigeminal:
General nerve of skin and
ophthalmic,
the face for Innervates the mucosa of the
maxillary,
SS touch, SM chewing face. Motor
mandibular
temperature, and muscles. fibers from
divisions. (V)
pain. trigeminal
motor nucleus
in pons.
Innervates lateral
Abducens
Abducens (VI) rectus muscle
SM nuclei in
(abducts the
inferior pons.
eye).
Innervates the
tear glands,
Sensory from Fibers emerge
nasal/palatine
Facial (VII) VS anterior taste from pons,
VM glands, and
SS buds. Small area lateral to
submandibular/s
of ear skin. abducens.
ublingual
salivary glands.
Sensory
Vestibular receptors in
branch: the ear:
Vestibuloco-
SS equilibrium. cochlea,
chlear (VIII)
Cochlear branch: semicircular
hearing. canals, and
vestibule.
*Glossopharyn VS Sensory from SM Innervates the Fibers emerge
geal (IX) SS posterior taste VM stylopharyngeus from medulla
buds, pharyngeal muscle (elevates oblongata.
mucosa, carotid pharynx during
body/sinus. swallowing).
Small area of Innervates the
external ear skin. parotid salivary
