The accessory nerve
Upon exiting the skull via the jugular foramen, the spinal accessory nerve pierces the sternocleidomastoid muscle before terminating on the trapezius muscle.
This is a cutaway profile of a head and throat, that shows the accessory nerve. The profile shows how upon exiting the skull via the jugular foramen, the spinal accessory nerve pierces the sternocleidomastoid muscle before terminating on the trapezius muscle.
Source
Boundless vets and curates high-quality, openly licensed content from around the Internet. This particular resource used the following sources: