nuclei of the Accessory nerve
- ambiguous nucleus
- spinal accessory nucleus
location and function of ambiguous nucleus
- medulla, forming an elongated column lying deep in reticular formation (inf continues with the spinal accessory nucleus)
- SVM
loaction and function of spinal accessory nucleus
- lateral part of anterior grey coloumn of c1-c5 segments
- somatomotor
brain exit of Accessory nerve
- lateral paraolivary sulcus
- forms spinal segments c1-6: the cervical or spinal roots
dura penetration of Accessory nerve
jugular foramen pars nervosa
skull exit of Accessory nerve
jugular foramen pars nervosa
how does the Accessory nerve arise
as two roots
- cranial root
- spinal root
cranial root
from the caudal part of the nucleus ambiguous, emerges from the side of the medulla from the lateral paraolivary sulcus
spinal root
from the spinal nucleus of the Accessory nerve that forms a narrow coloumn at the level of c1-c5
large moter neuron cells lay in the lateral aspect of anterior horn
(ventral cells supply the SCM m and the caudal cells supply the trapezius muscle)
the fibers will emerge from the ventrolateral part of the first five segment of spinal cord between the 2 roots spinal nerve to combine together and form the spinal root of accessory nerve ascending up into the cranium via foramen magnum
what happens to the roots of the Accessory nerve
unite to form the accessory nerve trunk which divedes again upon entering the jugular foramen into two branches
- internal jugular branch
- external jugular branch
internal jugular branch
carries fibers of the cranial root, unites with the vagus in the jugular foramen and supplies all the muscles of the larynx except cricothyroid via the recurrent laryngeal nerve, muscles of the pharynx and soft palate
external branch
continues independently through the jugular foramen to supply the sternocleidomastod and trapezius muscles
