sternomastoid

Supraclavicular, just above and behind the clavicle, at the sternomastoid muscle.

At the side the outline of the sternomastoid muscle is the most striking mark; it divides the anterior triangle of the neck from the posterior.

Deep within these muscle and ligament structures lie the mastoid fascia and the tendinous origin of the sternomastoid muscle.

The gland is covered anteriorly with infrahyoid muscles and laterally with the sternocleidomastoid muscle also known as sternomastoid muscle.

But the common carotid pulse in the neck is best palpated with the thumb placed alongside the sternomastoid muscle (the most prominent muscle in the neck), the left thumb being used for the patient's right side.

Fibromatosis colli (also known as "Sternomastoid tumor of infancy") is a benign proliferation of fibrous tissue infiltrating the lower third of the sternocleidomastoid or shoulder region, and is the most common cause of neonatal torticollis.