Chapter 20: Hypoglossal & Spinal Accessory Nerves Flashcards
With one exception, spinal nerves have both _____ and _____ roots.
- Dorsal (posterior)
- Ventral (anterior) roots
The _____ root is purely motor, and the _____ root is purely sensory.
- Ventral (anterior)
- Dorsal root is purely sensory
The first cervical nerve is unique: it is the only _____ that does not have a sensory root.
- Spinal nerve
The _____ has only a motor root.
- First cervical nerve
Since there is no sensory root, the first cervical nerve does not have a _____.
- Dorsal root ganglion
Like the first cervical nerve, the XIth and XIIth cranial nerves are purely _____.
- Motor
The XIIth _____ arises near the lowest part of the medulla.
- Cranial nerve
The XIIth cranial nerve leaves the _____ inside the foramen magnum and exits the skull through the hypoglossal foramen.
- Medulla
The _____ is named for the hypoglossal nerve which passes through it.
- Hypoglossal foramen
The XIIth cranial nerve is called the _____ nerve because it innervates the tongue from below. (Greek: hypo = below, glossa = tongue).
- Hypoglossal
The _____ nuclei contain the lower motor neurons whose axons form the _____ nerve.
- Hypoglossal
- Hypoglossal
The hypoglossal nerve innervates the muscles of the _____.
- Tongue
The right and left hypoglossal nuclei are just anterior to the central canal of the lower _____.
- Medulla
Each hypoglossal nucleus in served by a right or left paramedian branch of the _____.
- Anterior spinal artery
Occlusion of a paramedian branch of anterior spinal artery will cause _____ of the _____.
- Infarction
- Ipsilateral hypoglossal nucleus
Occlusion of the _____ will cause infarction of both hypoglossal nuclei.
- Anterior spinal artery
Since the hypoglossal nerve is the motor nerve of the _____, infarction of the hypoglossal nuclei will cause paralysis of the _____.
- Tongue
- Tongue
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.
- Anterior spinal artery
- Infarction (or death)
Infarction of one hypoglossal nerve causes _____ of the ipsilateral side of the _____.
- Paralysis
- Tongue
The hypoglossal nerves leave the _____ just posterior to the pyramids.
- Lower medulla
The pyramids carry the corticospinal axons along the _____ edge of the medulla.
- Anterior
The pyramids are the medullary portion of the _____ tracts.
- Corticospinal
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 _____.
- Anterior spinal artery
Occlusion of a _____ of the anterior spinal artery causes infarction of the hypoglossal nerve and the pyramid on that side.
- Paramedian branch
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 _____.
- Tongue
- Tongue
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.
- Corticospinal
The axons in the corticospinal tracts _____ at the lowest level of the medulla or in the spinal cord.
- Cross
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.
- Alternating hemiplegia
- Tongue
- Opposite (or contralateral)
The hypoglossal nerve exits the _____ between the long ridge of the pyramid and the short ridge of the olive.
- Medulla
The ridge just posterior to the exit of the _____ is called the olive.
- Hypoglossal nerve
The olive is a _____ created by the internal presence of the _____.
- Ridge
- Inferior olivary nucleus
The hypoglossal nerve exits the lower medulla between the _____ and the _____.
- Pyramid
- Olive
The roots of the _____ nerve emerge from the lower medulla between the pyramid and the olive.
- Hypoglossal
The olive is _____ to the pyramid.
- Posterior (or dorsal)
The XIth cranial nerve used to be called the _____ nerve because all of its roots leave from the upper five levels of the cervical _____.
- Spinal accessory
- Spinal cord
Many small roots leave the upper five cervical levels of the spinal cord and join to form the _____ cranial nerve.
- XIth
XI is considered a cranial nerve because it enters the posterior _____ fossa through the foramen magnum.
- Cranial
Within the _____ fossa XI shares a sheath with X.
- Posterior cranial
_____ is called the accessory nerve due to a mistaken belief that it contributes fibers to _____ inside their shared _____.
- XI
- X
- Sheath
Although X and XI share a sheath, there is no sharing of _____ between them.
- Fibers (or axons)
As befits a nerve arising from _____ cord levels, the _____ innervates neck muscles: the sternocleidomastoid and the trapezius.
- Cervical
- Accessory nerve
The accessory nerve leaves the posterior cranial fossa through the jugular foramen and splits into a nerve to the _____ and a nerve to the _____.
- Sternocleidomastoid
- Trapezius
XI passes through the _____ foramen next to X and IX.
- Jugular
The _____ contains the axons of the lower motor neurons for the _____ and trapezius muscles.
- Accessory nerve
- Sternocleidomastoid
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.
- Lower motor neurons
- Accessory nerve
The _____ nucleus is a column of lower motor neurons on the lateral edge of the _____ of the _____ spinal cord.
- Accessory
- Anterior horn
- Cervical
