Peripheral Nervous System

Front 1

How many spinal nerves are there?

Back 1

Thirty-one pairs

• Eight cervical nerve pairs (C1 through C8)
• Twelve thoracic nerve pairs (T1 through T12)
• Five lumbar nerve pairs (L1 through L5)
• Five sacral nerve pairs (S1 through S5)
• One coccygeal nerve pair

Front 2

Cauda equina

Back 2

describes the appearance of the lower end of the spinal cord and its spinal nerves as a horse’s tail

Front 3

Dorsal ramus

Back 3

supplies somatic motor and sensory fibers to smaller
nerves that innervate the muscles and skin of the posterior surface of
the head, neck, and trunk

Front 4

Ventral ramus

Back 4

Autonomic motor fibers split from the ventral ramus and head toward a ganglion of the sympathetic chain

Front 5

Cervical plexus

Back 5

Located deep within the neck

Made up of ventral rami of C1 through C4 and a branch of the ventral ramus of C5

Phrenic nerve exits the cervical plexus and innervates the exits diaphragm

Front 6

Ramus

Back 6

One of several large branches formed after each spinal nerve
emerges from the spinal cavity

Front 7

Brachial plexus

Back 7

Located deep within the
shoulder

Made up of ventral rami of C5 through T1

Front 8

Lumbar plexus

Back 8

Located in the lumbar region of the back in the psoas muscle

Formed by intermingling fibers of L1 through L4

Femoral nerve exits the lumbar plexus, divides into many branches, and supplies the thigh and leg

Front 9

Sacral plexus and coccygeal plexus

Back 9

Located in the pelvic cavity in the anterior surface of the
piriformis muscle

Formed by intermingling of fibers from L4 through S4

Tibial, common , peroneal, and sciatic nerves, exit the sacral plexus exit and supply nearly all the skin of leg, posterior thigh muscles, and leg and foot muscles

Front 10

Dermatome

Back 10

region of skin surface area supplied by afferent (sensory) fibers of a given spinal nerve

Front 11

Myotome

Back 11

skeletal muscle(s) supplied by efferent (motor) fibers of a given spinal nerve

Front 12

Olfactory nerve

Back 12

Carries information about sense of smell

Front 13

Optic nerve

Back 13

Carries visual information from the eyes to the brain

innermost layer of sensory neurons of the retina

Front 14

Oculomotor nerve

Back 14

regulates amount of light entering eye and aids in focusing on near objects

Front 15

Trochlear nerve

Back 15

Motor fibers originate in cells of the midbrain and extend to the superior oblique muscles of the eye

Front 16

Trigeminal nerve

Back 16

Has three branches: ophthalmic nerve
maxillary nerve
mandibular nerve

Sensory neurons carry afferent impulses from skin and neurons mucosa of head and teeth to cell bodies in the trigeminal to ganglion

Front 17

Abducens nerve

Back 17

Motor nerve with fibers originating from a nucleus in the nerve pons on the floor of the fourth ventricle and extending to the on lateral rectus muscles of the eye

Contains afferent fibers from proprioceptors in the lateral rectus muscles

Front 18

Facial nerve

Back 18

Motor fibers originate from a nucleus in the lower part of the pons and extend to superficial muscles of the face and scalp

Also contains sensory fibers from taste buds of anterior two thirds of the tongue

Front 19

Vestibulocochlear nerve

Back 19

Two distinct divisions that are both sensory: vestibular nerve and cochlear nerve

Front 20

Vestibular nerve

Back 20

fibers originate in the semicircular canals in inner ear and transmit impulses that result in sensations of equilibrium

Front 21

Cochlear nerve

Back 21

fibers originate in the organ of Corti in the cochlea of
the inner ear and transmit impulses that result in sensations of hearing

Front 22

Glossopharyngeal nerve

Back 22

Supplies fibers to tongue, pharynxtongue, pharynx, and carotid sinus

Front 23

Somatic reflex

Back 23

contraction of skeletal muscles

Front 24

Autonomic (visceral) reflex

Back 24

either contraction of smooth or cardiac muscle or secretion by glands

Front 25

Preganglionic neuron

Back 25

conducts impulses from central nervous system to an autonomic ganglion

Front 26

Postganglionic neuron

Back 26

efferent neuron, with which a preganglionic neuron synapses within autonomic ganglion, and neuron sends efferent fiber to the effectors

Front 27

Sympathetic chain ganglia

Back 27

Usually there are 22 sympathetic chain ganglia on each side of vertebral column: 3 cervical, 11 thoracic, 4 lumbar, and 4 sacral