Chapter 21

Question 1

Spinal Nerves

Answer 1

31 pairs

(7) cervical vertebra,
(8) cervical nerve pairs (C1-C8)
(12) thoracic nerve pairs (T1-T12)
(5) lumbar nerve pairs (L1-L5)
(5) sacral nerve pairs (S1-S5)
(1) coccygeal pair of spinal nerves

Question 2

Cervical Plexus

Answer 2

Found deep within the neck

Ventral rami of the first four cervical spinal nerves (C1-C4)

Along with a branch of ventral ramus of C5, exchange fibers in the cervical plexus

Question 3

Phrenic Nerve

Answer 3

Helps to breath

Question 4

Brachial Plexus

Answer 4

Found deep within the shoulder

Passes from C5 through T1, beneath the clavicle (collarbone)

Question 5

Lumbar Plexus

Answer 5

Formed by the intermingling of fibers from the first four lumbar nerves

Large femoral nerve

Question 6

Sacral Plexus

Answer 6

Form by fibers from fourth and fifth lumbar (L4&L5) and the first four sacral nerves (S1-S4)

Question 7

Sciatic nerve

Answer 7

Forms the largest nerve in the body

Question 8

Dermatone

Answer 8

Skin surface area supplied by sensory fibers of a given spinal nerve: this is also a name that means “skin section”

Question 9

CN I Olfactory

Answer 9

Sense of smell

Question 10

CN II Optic

Answer 10

Vision

Question 11

CN III Oculomotor

Answer 11

Eye movements, regulation of size of pupil, accommodation (for near vision), proprioception (muscle sense)

Question 12

CN IV Trochlear

Answer 12

Eye movements, proprioception

Question 13

CN V Trigeminal

Answer 13

Sensations of head and face, chewing movements, proprioception

Question 14

CN VI Abducens

Answer 14

Abduction of eye, proprioception

Question 15

CN VII Facial

Answer 15

Facial expressions, secretion of saliva and tears, taste

Question 16

CN VIII Vestibulo-cochlear

Answer 16

Balayage or equilibrium sense; hearing

Question 17

CN IX Glossopharyngeal

Answer 17

Sensations of tongue, swallowing movements, secretion of saliva, aid in reflex control of blood pressure and respiration

Question 18

CN X Vagus

Answer 18

Sensations and movements of organs supplied; e.g., slows heart, increases peristalsis, contracts muscles for voice production

Question 19

CN XI Accessory

Answer 19

Movements of viscera, voice production

Question 20

CN XII Hypoglossal

Answer 20

Tongue movements, proprioception

Question 21

Withdrawal reflex

Answer 21

You accidentally touch a very hot surface, you reflexively withdraw from it to avoid further injury

Question 22

Knee jerk reflex (patellar reflex)

Answer 22

An extension of the leg in response to tapping of the patellar ligament

Question 23

Sensory neurons

Answer 23

Peripheral axon fibers- in femoral and second, third, and fourth lumbar nerves
Cell bodies- second, third, and fourth lumbar ganglia
Central axon fibers- in posterior roots of second, third, and fourth lumbar nerves; terminate in these segments of the spinal cord; synapse directly with LMNs

Question 24

Reflex center

Answer 24

Synapses in anterior gray column between axons of sensory neurons and dendrites and cell bodies of LMNs

Question 25

Motor neurons

Answer 25

Dendrites and cell bodies- in spinal cord anterior gray column Axons- in anterior roots of second, third, and fourth lumbar spinal nerves and femoral nerves; terminate in quadriceps femoris muscle

Question 26

Ankle jerk reflex (Achilles reflex)

Answer 26

An extension (plantar flexion) of the foot in response to tapping of the Achilles tendon

Question 27

Plantar reflex

Answer 27

Consists of a curling under of all the toes (plantar flexion) plus a slight turning in and flexion of the anterior part of the foot in response to stimulation of the outer edge of the sole

Question 28

Babinski sign

Answer 28

An extension of the great toe, with or without fanning of the other toes

Question 29

Corneal reflex

Answer 29

Blinking in response to the cornea being touched

Question 30

Abdominal reflex

Answer 30

Occurs when the umbilicus moves in response to striking the side of the abdomen