Chapter 20 Hypoglossal & Accessory Nerves

Question 1

With one exception, spinal nerves have both __________ and __________ roots.

Answer 1

dorsal (posterior)

ventral (anterior)

Question 2

The __________ root is purely motor, and the ___________ _________ is purely sensory.

Answer 2

ventral (anterior)

dorsal root

Question 3

The first cervical nerve is unique: it is the only _________ nerve that does not have a sensory root.

Answer 3

spinal

Question 4

The ________ _____________ _________ has only a motor root.

Answer 4

first cervical nerve

Question 5

Since there is no sensory root, the first cervical nerve does not have a __________ ________ ganglion.

Answer 5

dorsal root

Question 6

Like the first cervical nerve, the XIth (accessory) and XIIth (hypoglossal) cranial nerves are purely __________.

Answer 6

motor

Question 7

The XIIth cranial nerve arises near the

Answer 7

lowest part of the medulla.

Question 8

The XIIth (hypoglossal) cranial nerve leaves the medulla inside the ___ and exits the skull through the ____

Answer 8

foramen magnum

hypoglassal foramen

Question 9

The _______________ ____________ is named for the hypoglossal nerve which passes through it.

Answer 9

hypoglossal foramen

Question 10

The XIIth cranial nerve is called the hypoglossal nerve because

Answer 10

it innervates the tongue from below. (Greek: hypo=below, glossa=tongue.)

Question 11

The hypoglossal nuclei contain the lower motor neurons whose axons form the _______________ nerve.

Answer 11

hypoglossal

Question 12

The hypoglossal nerve innervates the muscles of the ____________.

Answer 12

tongue

Question 13

The right and left hypoglossal nuclei are just anterior to the central canal of the ___ ____.

Answer 13

lower medulla

Question 14

Each hypoglossal nucleus in served by a right or left paramedian branch of the _____________ ________ ___________.

Answer 14

anterior spinal artery

Question 15

Occlusion of a paramedian branch of anterior spinal artery will cause infarction of the ____ ________________ __________.

Answer 15

ipsilateral hypoglossal nucleus (same side)

Question 16

Occlusion of a paramedian branch of anterior spinal artery will cause infarction of the __ ________________ __________.

Answer 16

ipsilateral hypoglossal nucleus

Question 17

Occlusion of the ______________ ________ __________ will cause infarction of both hypoglossal nuclei.

Answer 17

anterior spinal artery

Question 18

Since the hypoglossal nerve is the motor nerve of the __________, infarction of the hypoglossal nuclei will cause paralysis of the ___________.

Answer 18

tongue

tongue

Question 19

Since a hypoglossal nerve gets its blood supply from an ipsilateral paramedian branch of the _____________ ________ __________, occlusion of this branch artery causes ______________ of the hypoglossal nerve, even if the hypoglossal nucleus has collateral circulation.

Answer 19

anterior spinal artery

infarction (or death)

Question 20

Infarction of one hypoglossal nerve causes _______________ of the ____ side of the ___________.

Answer 20

paralysis
ipsilateral
tongue

Question 21

The hypoglossal nerves leave the __________ _____________ just posterior to the pyramids

Answer 21

lower medulla

Question 22

The pyramids carry the corticospinal axons along the _______________ edge of the medulla.

Answer 22

anterior

Question 23

The pyramids are the medullary portion of the ____________________ tracts.

Answer 23

corticospinal

Question 24

A pyramid and the hypoglossal nerve that exits the lower medulla posterior to it get their blood supply from the same paramedian branch of the ______________ _________ _________.

Answer 24

anterior spinal artery

Question 25

Occlusion of a _______________ _________ of the anterior spinal artery causes infarction of the hypoglossal nerve and the pyramid on that side.

Answer 25

paramedian branch

Question 26

Occlusion of a paramedian branch of the anterior spinal artery causes paralysis of that side of the ____________ because each hypoglossal nerve innervates the muscles of the ____ of the ____________.

Answer 26

tongue same side tongue

Question 27

Occlusion of a paramedian branch of the anterior spinal artery causes paralysis of the opposite side of the body because the ____________________ tracts cross below the level of the exit of the hypoglossal nerve.

Answer 27

corticospinal

Question 28

The axons in the corticospinal tracts _________ at the lowest level of the medulla or in the spinal cord.

Answer 28

cross

Question 29

The paralysis caused by occlusion of one paramedian branch of the anterior spinal artery is called an alternating hemiplegia because the ____________ is paralyzed on same side and the rest of the body is paralyzed on the _____________ side.

Answer 29

tongue | opposite (or contralateral)

Question 30

The hypoglossal nerve exits the ____________ between the long ridge of the pyramid and the short ridge of the olive.

Answer 30

medulla

Question 31

The ridge just posterior to the exit of the hypoglossal nerve is called the __.

Answer 31

olive

Question 32

The olive is a __________ created by the internal presence of the inferior olivary nucleus.

Answer 32

ridge

Question 33

The hypoglossal nerve exits the lower medulla between the ____________ and the ________.

Answer 33

pyramid | olive

Question 34

The accessory nucleus is a column of lower motor neurons on the lateral edge of the ______________ _________ of the _________ ____________ cord.

Answer 34

anterior horn | cervical spinal

Question 35

The roots of the __________________ nerve emerge from the lower medulla between the pyramid and the olive.

Answer 35

hypoglossal

Question 36

The olive is ____________ to the pyramid.

Answer 36

posterior (or dorsal)

Question 37

The XIth cranial nerve used to be called the spinal accessory nerve because all of its roots leave from the upper five levels of the ___ ___________ ________.

Answer 37

cervical spinal cord

Question 38

Many small roots leave the upper five cervical levels of the spinal cord and join to form the ______ cranial nerve.

Answer 38

XI th (accessory)

Question 39

XI is considered a cranial nerve because it enters the posterior cranial fossa through the ___

Answer 39

foramen magnum.

Question 40

Within the ________________ __________ fossa XI shares a sheath with X.

Answer 40

posterior cranial

Question 41

XI is called the accessory nerve due to a mistaken belief that it contributes fibers to _____ inside their shared _________..

Answer 41

X (vagus) | sheath

Question 42

Although X and XI (vagus and hypoglossal) share a sheath, there is no sharing of ________ between them

Answer 42

fibers (axons)

Question 43

As befits a nerve arising from ___________ cord levels, the accessory nerve innervates neck muscles: the sternocleidomastoid and the trapezius.

Answer 43

cervical

Question 44

The accessory nerve leaves the posterior cranial fossa through the jugular foramen and splits into a nerve to the ________________________ and a nerve to the _______________.

Answer 44

sternocleidomastoid | trapezius

Question 45

XI (accessory) passes through the _____________ next to X and IX (glossopharyngeal and vagus)

Answer 45

jugular formen

Question 46

The accessory nerve contains the axons of the lower motor neurons for the _____________________ and _____________ muscles.

Answer 46

sternocleidomastoid | trapezius

Question 47

The ___________ ___________ _____________ whose axons join to form the accessory nerve are in a cell column in the anterior horn of the upper cervical cord and the lowest level of the medulla

Answer 47

lower motor neurons