Chapter 20: Hypoglossal & Spinal Accessory Nerves

Question 1

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

Answer 1

• Dorsal (posterior)

- Ventral (anterior) roots

Question 2

The _____ root is purely motor, and the _____ root is purely sensory.

Answer 2

• Ventral (anterior)

- Dorsal root is purely sensory

Question 3

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

Answer 3

• Spinal nerve

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 _____.

Answer 5

• Dorsal root ganglion

Question 6

Like the first cervical nerve, the XIth and XIIth cranial nerves are purely _____.

Answer 6

• Motor

Question 7

The XIIth _____ arises near the lowest part of the medulla.

Answer 7

• Cranial nerve

Question 8

The XIIth cranial nerve leaves the _____ inside the foramen magnum and exits the skull through the hypoglossal foramen.

Answer 8

• Medulla

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

Answer 10

• Hypoglossal

Question 11

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

Answer 11

• Hypoglossal

- 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 lower _____.

Answer 13

• 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 _____ of the _____.

Answer 15

• Infarction

- Ipsilateral hypoglossal nucleus

Question 16

Occlusion of the _____ will cause infarction of both hypoglossal nuclei.

Answer 16

• Anterior spinal artery

Question 17

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

Answer 17

• Tongue

- Tongue

Question 18

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 18

• Anterior spinal artery

- Infarction (or death)

Question 19

Infarction of one hypoglossal nerve causes _____ of the ipsilateral side of the _____.

Answer 19

• Paralysis

- Tongue

Question 20

The hypoglossal nerves leave the _____ just posterior to the pyramids.

Answer 20

• Lower medulla

Question 21

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

Answer 21

• Anterior

Question 22

The pyramids are the medullary portion of the _____ tracts.

Answer 22

• Corticospinal

Question 23

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 23

• Anterior spinal artery

Question 24

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

Answer 24

• Paramedian branch

Question 25

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 same side of the _____.

Answer 25

- Tongue | - Tongue

Question 26

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 26

- Corticospinal

Question 27

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

Answer 27

- Cross

Question 28

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

Answer 28

- Alternating hemiplegia - Tongue - Opposite (or contralateral)

Question 29

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

Answer 29

- Medulla

Question 30

The ridge just posterior to the exit of the _____ is called the olive.

Answer 30

- Hypoglossal nerve

Question 31

The olive is a _____ created by the internal presence of the _____.

Answer 31

- Ridge | - Inferior olivary nucleus

Question 32

The hypoglossal nerve exits the lower medulla between the _____ and the _____.

Answer 32

- Pyramid | - Olive

Question 33

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

Answer 33

- Hypoglossal

Question 34

The olive is _____ to the pyramid.

Answer 34

- Posterior (or dorsal)

Question 35

The XIth cranial nerve used to be called the _____ nerve because all of its roots leave from the upper five levels of the cervical _____.

Answer 35

- Spinal accessory | - Spinal cord

Question 36

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

Answer 36

- XIth

Question 37

XI is considered a cranial nerve because it enters the posterior _____ fossa through the foramen magnum.

Answer 37

- Cranial

Question 38

Within the _____ fossa XI shares a sheath with X.

Answer 38

- Posterior cranial

Question 39

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

Answer 39

- XI - X - Sheath

Question 40

Although X and XI share a sheath, there is no sharing of _____ between them.

Answer 40

- Fibers (or axons)

Question 41

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

Answer 41

- Cervical | - Accessory nerve

Question 42

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 42

- Sternocleidomastoid | - Trapezius

Question 43

XI passes through the _____ foramen next to X and IX.

Answer 43

- Jugular

Question 44

The _____ contains the axons of the lower motor neurons for the _____ and trapezius muscles.

Answer 44

- Accessory nerve | - Sternocleidomastoid

Question 45

The _____ whose axons join to form the _____ are in a cell column in the anterior horn of the upper cervical cord and the lowest level of the medulla.

Answer 45

- Lower motor neurons | - Accessory nerve

Question 46

The _____ nucleus is a column of lower motor neurons on the lateral edge of the _____ of the _____ spinal cord.

Answer 46

- Accessory - Anterior horn - Cervical