Anatomy and Physiology- The Peripheral Nervous System

The Peripheral Nervous System

the sensory and motor neurons that connect the central nervous system to the rest of the body

Somatic Nervous System

the division of the peripheral nervous system that is under conscious control. Connects the CNS to the body's skeletal muscles and skin

The Autonomic Nervous system

the division of the peripheral nervous system that is not under conscious control. Connects the body's organs to the central nervous system

Endoneurium

delicate connective tissue around individual nerve fibers in nerve

Perineurium

Thick sheet of connective tissue that holds many nerve fibers together.

Epineurium

Dense connective tissue that surrounds entire nerve including fascicles and blood vessels.

Sensory Nerve

carries messages toward the brain and spinal cord from a receptor; afferent nerve

Motor nerves

Efferent nerves, Nerves that carry information from the central nervous system to the muscles or glands of the body.

Mixed Nerves

nerves carrying both sensory and motor fibers

olfactory nerve (I)

Sensory nerve only

Associated with sense of smell

Optic Nerve (II)

sensory only nerve, Associated with sense of vision

Oculomotor Nerve (III)

Primarily motor nerve, moves the eyes and eyelids, adjusts the amount of light entering the eye.(autonomic)

Small sensory component (proprioceptive fibers)

Trochlear Nerve (IV)

Smallest pair of cranial nerves

Primarily motor nerve

Motor impulses to one pair of muscles that move the eyes

Trigeminal Nerve (V)

Mixed nerve with three branches; Opthalmic, Maxillary, and Mandibular. All three branches provide sensory information. Also controls muscles of mastication (Chewing)

Abducens Nerve (VI)

Primarily motor nerve

Motor impulses to one pair

of muscles that move the eyes

Some sensory (proprioceptive

fibers)

Facial Nerve (VII)

a mixed nerve. Sensory from taste receptors Motor to muscles of facial expression, tear glands, and salivary glands

vestibulocochlear nerve (VIII)

Acoustic or auditory nerve

Sensory nerve only made of 2 branches:

Vestibular and Cochlear branches

Vestibular branch of CN VIII

Sensory from equilibrium receptors of ear

Cochlear Branch of CN VIII

Sensory from hearing receptors

Glossopharyngeal Nerve (IX)

Mixed nerve

Sensory from pharynx, tonsils, part of tongue

Motor to salivary glands and muscles of pharynx (for swallowing)

Vagus Nerve (X)

Mixed nerve,

*Somatic motor to muscles of speech and swallowing

*Autonomic motor to heart,

other viscera of thorax and abdomen

*Sensory from pharynx, larynx, esophagus, and viscera of thorax and abdomen

Accessory Nerve (XI)

Primarily a motor cranial nerve; innervates muscles to control swallowing and innervates other muscles to move head, neck, and shoulders

Hypoglossal Nerve (XII)

Primarily motor

Motor to muscles of the tongue for speaking, chewing, swallowing

spinal nerves

31 pairs of nerves arising from the spinal cord

number of cervical spinal nerves

8 pairs

number of thoracic spinal nerves

12 pairs

number of lumbar spinal nerves

5 pairs

number of sacral spinal nerves

5 pairs

number of coccygeal spinal nerves

1 pair

dermatome

Area of skin supplied by a single spinal nerve

cervical plexus

C1-C4; innervates superficial neck structures, skin of neck, posterior portion of head

brachial plexus

C5-T1

innervates the pectoral girdle and upper limbs

musculocutaneous nerve

Supply muscles of anterior arms and skin of forearms

ulnar and median nerves

Supply muscles of forearms and hands, skin of hands

radial nerve

Supply posterior muscles of arms and skin of forearms and hands.

Axillary Nerve

Supply muscles and skin of anterior, lateral, and posterior arms.

lumbosacral plexus

Formed of L2-S2 rami. Supplies the lower limb.

obturator nerve

passes through obturator foramen to innervate adductor muscles

femoral nerve

innervates quadriceps and skin of anterior thigh and medial surface of leg

sciatic nerve

Supply muscles and skin of thighs, legs and feet; largest and longest nerve in the body