Overview
It arises on the manubrium of the sternum and runs along the ventrolateral neck to the head. In cattle it divides into two parts:
- Sternomandibularis (pars mandibularis): the more superficial; it ends on the mandible.
- Sternomastoideus (pars mastoidea): deep; it ends in the region of the mastoid process.
Origin
Manubrium of the sternum.
Insertion
- Sternomandibularis: ventral border of the mandible, next to the rostral border of the masseter.
- Sternomastoideus: mastoid process of the temporal bone.
Action
Draws the head and neck ventrally or to the same side.
Innervation
Ventral branch of the accessory nerve (n. accessorius).
Clinical relevance
It forms the ventral border of the jugular groove. In cattle the external jugular vein, which runs in this groove, is used for drawing blood and for intravenous medication, for example calcium for periparturient hypocalcaemia (milk fever).