Quiz 9: Sidman (Ch 50)

Question 1

Brainstem nuclei are collections of neuron cell bodies. The nuclei are part of the _____ matter. The cranial nerves and nuclei are designated by Roman numerals. The somatic group is made up of four nuclei associated with cranial nerves III, IV, VI, and XII. Nucleus XII, the most inferior in position, innervates the tongue, while _____, _____, and _____ innervate the _____ muscles of the eye.

Answer 1

gray; III; IV; VI; extraocular

Question 2

Of the four somatic brainstem nuclei, cranial nucleus IV supplies an _____ muscle. Cranial nucleus III supplies several _____ muscles. Cranial nucleus _____ supplies the tongue muscles. Cranial nucleus _____ supplies one extraocular muscle.

Answer 2

extraocular; extraocular; XII; VI

Question 3

Since its axons constitute the hypoglossal nerve, the XIIth nucleus is also called the _____ nucleus.

Answer 3

hypoglossal

Question 4

A major action of the tongue muscles is to push the tongue forward and allow it to protrude from the mouth. The musculature of the left side, if unopposed, would push the tongue _____ and to the right. Equal action of muscles of both sides cause the tongue to protrude _____ ahead.

Answer 4

forward; straight

Question 5

A patient has a lesion affecting the right hypoglossal nucleus or nerve. He was asked to stick out his tongue. It protrudes forward and to his right because the intact muscles of the _____ side push unopposed. Innervated tongue muscles of one side, if unopposed, push the tongue forward and toward the _____ side.

Answer 5

left; contralateral

Question 6

A patient whose tongue protrudes to the left may have normally functioning muscle in the _____ side and impaired muscle in the _____ side of the tongue. The hypoglossal nerve or nucleus may be impaired on the _____ side. The protruding tongue “points _____ the side of the hypoglossal lesion.”

Answer 6

right; left; left; toward

Question 7

The hypoglossal nucleus supplies the _____ muscles. Cranial nerve VI, _____, and _____ supply the extraocular muscles. The extraocular muscles that contract and turn the eyes from left to right and right to left are the medial _____ and the _____ _____ muscles.

Answer 7

tongue; III; IV; rectus; lateral rectus

Question 8

The eyeball is abducted (moved outward) by contraction of the _____ rectus muscle. Contraction of the _____ _____ muscle adducts (moves inward) the eye.

Answer 8

lateral; medial rectus

Question 9

In order to look towards the left with both eyes, the _____ lateral rectus and the _____ medial rectus both need to contract.

Answer 9

left; right

Question 10

Cranial motor nuclei controlling the extraocular muscles have the same names as the corresponding cranial nerves. Cell bodies of the abducens nerve constitute the _____ nucleus. The abducens nucleus and nerve supply the lateral rectus muscle. Right lateral gaze requires excitation of cranial nerve VI on the _____ side.

Answer 10

abducens; right

Question 11

The lateral rectus is supplied by cranial nerve _____, named the _____ nerve. Cranial nerve IV (the trochlear) supplies the superior oblique muscle. All of the other extraocular muscles are supplied by cranial nerve _____, the oculomotor nerve. How many extraocular muscles does the oculomotor nerve innervate? _____

Answer 11

VI; abducens; III; four

Question 12

Draw a line connecting the medial rectus muscle with its nucleus and another line connecting that nucleus with the appropriate cranial nerve number. Do the same for the superior oblique muscle.

Answer 12

Medial rectus muscle - Oculomotor nucleus - III
Superior oblique muscle - Trochlear nucleus - IV

Question 13

This eye is on the _____ side of the head. Place a Roman numeral on or beside each of the six extraocular muscles to indicate its source of innervation.

Answer 13

left
IV on top left
III on bottom left
clockwise on eye: III, IV, III, III

Question 14

When the right eye moves outward, the _____ rectus muscle of that eye contracts and the _____ _____ muscle of the same eye simultaneously relaxes. The simultaneous contraction and relaxation of extraocular muscles is accomplished by excitation and _____ of the appropriate cranial nerve nuclei in the brainstem.

Answer 14

lateral; medial rectus; inhibition

Question 15

Muscle action in both eyes must be integrated for focused vision. Right lateral gaze requires contraction of the right _____ _____ muscle and left _____ _____ muscle. Simultaneously, there is relaxation of the lateral rectus on the _____ side of the medial rectus on the _____ side.

Answer 15

lateral rectus; medial rectus; left; right

Question 16

The superior rectus pulls the eye up and rotates it slightly. An eye initially turned outward is pulled directly upward by contraction of the _____ rectus.

Answer 16

superior

Question 17

In many situations, the rotating effect of the rectus muscles may be ignored. Upward gaze mainly involves simultaneous contraction of the _____ rectus of each eye and relaxation of the _____ rectus of each eye.

Answer 17

superior; inferior

Question 18

All of the extraocular muscles, except the superior oblique and the _____ _____, are supplied by cranial nerve _____. The three rectus muscles supplied by cranial nerve III are the _____ rectus, the _____ rectus, and the _____ rectus. The extraocular muscle contracting most strongly in the diagram is innervated by cranial nerve _____.

Answer 18

lateral rectus; III; medial; superior; inferior; VI

Question 19

Axons of cranial nerve VI arise from cell bodies in the brainstem nucleus named the _____ nucleus. Downward gaze involves simultaneous contraction of the inferior rectus muscles and relaxation of the superior rectus muscles in both eyes. When the eyes move upward or downward, some neurons in the _____ nucleus are excited, and others are _____. Both of these nuclei are classified among the _____ motor nuclei of the brainstem.

Answer 19

abducens; oculomotor; inhibited; somatic

Question 20

Cranial nerve IV arises from the IVth, or _____, nucleus and supplies the superior _____ muscle. The inferior oblique is supplied by cranial nerve _____.

Answer 20

trochlear; oblique; III

Question 21

With Roman numerals, designate which cranial nerves supply the following muscles:
Superior oblique: _____
Inferior oblique: _____
Inferior rectus: _____
Superior rectus: _____
Medial rectus: _____
Lateral rectus: _____

Answer 21

IV; III; III; III; III; VI

Question 22

Provide the name for each numbered nucleus (and nerve):
XII: _____
IV: _____
VI: _____
III: _____
All are _____ motor nuclei of the brainstem.

Answer 22

hypoglossal; trochlear; abducens; oculomotor; somatic

Question 23

Name the muscles innervated by:
a. cranial nerve VI: _____
b. cranial nerve IV: _____
c. cranial nerve III: _____
d. cranial nerve XII: _____

Answer 23

a. lateral rectus; b. superior oblique; c. medial, superior, and inferior recti; d. tongue muscles

Question 24

If the lateral rectus muscle is paralyzed, then the eye will be pulled _____ward by the unopposed action of the _____ _____ muscle.

Answer 24

inward; medial rectus

Question 25

A patient who shows a right internal strabismus (a turning of the right eye toward the nose) may be suspected of having a weak _____ _____ muscle. He may have a lesion of the right _____ nerve. If the left oculomotor nerve is diseased, then movement of the left eye upward, downward, and _____ will be impaired.

Answer 25

lateral rectus; abducens; inward

Question 26

The remarkable coordination of several extraocular muscles of both eyes implies that there must be some rapidly conducting anatomical pathway that connects cranial nuclei _____, _____, and _____. Much of the coordination of the somatic motor nuclei is accomplished by a tract (fascicle) of nerve fivers that lies medially and runs longitudinally in the brainstem. It is called the m_____ l_____ fasciculus.

Answer 26

III; IV; VI; medial; longitudinal

Question 27

Eye movements are coordinated with other movements of the face and neck. The _____ _____ fasciculus interconnects nearly all motor nuclei of the cranial nerves.

Answer 27

medial; longitudinal

Question 28

When an individual is looking to the left and whistling, the _____ _____ _____ is coordinating almost simultaneous stimulation of the left _____ nucleus and the right ____ nucleus, inhibition of the _____ oculomotor and _____ abducens nuclei, and stimulation bilaterally of somatic motor nucleus _____ (tongue movements for whistling) and of some _____ motor nuclei (facial expression and phonation).

Answer 28

medial longitudinal fasciculus; abducens; oculomotor; left; right; XII; branchial