CN XI Flashcards
What is the name of CN XI?
Accessory nerve
What number is the accessory nerve?
CN XI
How is CN XI classified?
exclusively motor
How many roots does CN XI have?
two
What are the two roots of the accessory nerve?
cranial and spinal roots
What do the cranial and spinal roots contribute?
LMN’s
What do the cranial and spinal accessory roots innervate?
SCM, trapezius, muscle of the soft palate, pharynx, larynx
Where are the cell bodies of the cranial root of the accessory nerve found?
nucleus abiguus
Where is the spinal nucleus of the accessory nerve found?
anterior horn of the gray from level of the foramen magnum to C5/C6 cord level
Where is the apparent origin of the cranial root of the accessory nerve?
lateral aspect of the medulla oblongata
T/F: the spinal and cranial roots combine briefly traveling through the jugular foramen?
true
How does the cranial root exit the skull?
jugular foramen
Where do the cranial root and the spinal root split?
outside the skull
What else does the cranial root join with and where? (hint: not spinal root)
vagus nerve at inferior (nodose) ganglion
Where are the cranial nerve fibers that join with the vagus nerve distributed to?
pharyngeal plexus, external and recurrent laryngeal nerves
What do the cranial root fibers with the vagus nerve innervate?
laryngeal muscles, but NOT cricoarytenoid
T/F: the cranial root fibers are exclusively motor fibers?
false
What is the apparent origin of the spinal root of the accessory nerve?
lateral aspect of the cervical cord C5/C6 level between the anterior and posterior rootlets
Where does the trunk formed by the spinal root travel and in what direction?
ASCEND between the denticulate ligaments and in the posterior rootlets
How does the spinal rootlet enter the skull?
foramen magnum
What does the spinal root pass deep to and innervate?
sternocleidomastoid
After the nerve travels in the posterior triangle in travels deep to and innervates what?
trapezius
The trapezius receives innervation from the spinal root of accessory nerve and from what other probable source?
cervical plexus
What part of the trapezius does the spinal root of the accessory nerve supply?
upper and middle portions
What part of the trapezius of does the cervical plexus supply?
lower 2/3 of the muscle
What is spasmodic torticollis?
clinical problem with the accessory nerve
episodic contraction of the SCM and trapezius
What happens with interuption of the spinal nerve roots?
SCM paralysis: unable to turn face to contralateral side
R SCM issue = no L face turn
What happens if the trapezius cannot function?
unable to support the upper extremity
BRACHIAL PLEXUS tractioned = upper part damaged first
