Situated at the side and front of the upper part of the neck, it extends from the fifth cervical vertebra to the base of the skull.

Origin. - From the transverse processes of the 3rd, 4th, and 5th bones of the neck.

Insertion. - Into the base of the skull at the junction of the basilar process of the occiput with the sphenoid bone.

Action. - To draw the head to one side, or to flex it, according as it acts by itself or with the corresponding muscle on the other side.