Signal outflow in the 11th cranial nerve.

Nervus accessorius signal outflow.

Begins in the cervical segments of the spinal cord (C1 through C6) where a large number of thin nerve fibre bundles in a row from the bottom up protrude out of the lateral cord. The bundles merge into a unit that is close to the surface of the spinal cord and eventually disappears into the cranial cavity through the large neck hole (foramen magnum). The extra nerve reaches up to the place where the vagus nerve emerges from the medulla oblongata and then joins this nerve out of the cranial cavity where it motorically supplies a neck and a shoulder-neck muscle (m.sternocleidomastoid =nick muscle; m.trapezius = coat muscle).

Notice that when the m.sternocleidomastoid is activated on one side, the head is turned to the opposite side!!!