Medical expert of the article
New publications
Additional nerve
Last reviewed: 23.04.2024
All iLive content is medically reviewed or fact checked to ensure as much factual accuracy as possible.
We have strict sourcing guidelines and only link to reputable media sites, academic research institutions and, whenever possible, medically peer reviewed studies. Note that the numbers in parentheses ([1], [2], etc.) are clickable links to these studies.
If you feel that any of our content is inaccurate, out-of-date, or otherwise questionable, please select it and press Ctrl + Enter.
The additional nerve (n. Accessories), or the villis nerve, is formed by the processes of the motor nuclei located in the oblong brain and in the spinal cord.
Cranial roots (radices craniales) of the accessory nerve emerge from the posterior lateral groove of the medulla oblongata, behind the olive.
Spinal roots (radices spinales) appear from the posterolateral groove of the spinal cord, climb through the large occipital foramen into the cavity of the skull, and behind the lobules of the cerebellum hemisphere (amygdala of the cerebellum) connect to the cranium roots. At the exit from the jugular opening, the additional nerve gives the inner and outer branches. The inner branch (r. Internus), thinner, is part of the vagus nerve over its lower node. The outer branch (r. Externus) of the accessory nerve goes behind the styloid process of the temporal bone and the muscles starting from it, passes behind the posterior abdomen of the digastric muscle and is directed towards the sternocleidomastoid muscle. Some fibers of the outer branch perforate the sternocleidomastoid muscle and enter the anterior margin of the trapezius muscle that innervates.
The extra nerve gives the connecting branches to the anterior branches of the III and IV cervical spinal nerves and to the hyoid nerve.
[