Omohyoid muscle

The omohyoid muscle is a muscle of the neck that connects the scapula (shoulder blade) to the hyoid bone in the throat. It is used to depress the larynx, which it does indirectly by depressing the hyoid bone.

The omohyoid is a long, thin muscle that is separated into two sections of muscle tissue, called the upper and lower bellies, connected with a tendon in between.

Origin and Insertion
The omohyoid has its origin in the upper margin of the scapula, where the venter inferior, or lower belly, forms a narrow, flat fasciculus; it crosses behind the sternocleidomastoid muscle, becoming tendinous; then it turns at an oblique angle and ends in the venter superior, or upper belly. The latter then passes up the neck to the outer margin of the sternohyoid muscle, inserting itself into the lower edge of the hyoid bone, just outside the point where the sternohyoid muscle sticks in.

The central tendon of the omohyoid - whose form and length both vary greatly between individuals - is kept in place by the deep cervical fascia; further down, it is attached to the clavicle and the uppermost rib.

Variations
Either belly may be absent or doubled, so an individual may have from one to four bellies in each omohyoid muscle. The whole muscle may be doubled or even absent.

Word origin
The word omohyoid comes from omo, Greek for shoulder, and hyoid, referring to its insertion in the hyoid bone.