Compared to all other muscles of the neck, which are skeletal, this is the only cutaneous. It is a wide and thin lamina in the subcutaneous tissue. It covers the frontal and lateral side of the neck and the lower face. This muscle is cut when a myocutaneous flap is created.

It is a long and thick muscle, situated in the anterolateral region of the neck. It fits with one sternal, one mastoid, and one clavicular insertion. It covers the great vessels of the neck, and it is crossed superficially by the external jugular vein that goes behind the clavicle, near the frontal corner of the anterior triangle and the brachial plexus. At Erb’s point, the great auricular nerve, which derives from the cervical plexus, obliquely crosses the surface of the muscle upward (Fig. 3.2).

The suprahyoid muscles are located in the submandibular region superiorly to the hyoid bone and connect the hyoid to the skull. They are the geniohyoid (deep layer), the mylohyoid, the stylohyoid (middle layer), and the digastric muscle (superficial layer).

Infrahyoid muscles vary considerably in extent of their development. They connect the hyoid with the upper part of the thorax, shoulders, and larynx. They are the sternothyroid, thyrohyoid, sternohyoid, and omohyoid. They overlie the thyroid gland, the thyroid cartilage, the larynx, the trachea, and the esophagus.

The omohyoid muscle is an important landmark in the neck because it divides the anterior and posterior cervical triangles into smaller triangles. Also known as “resident’s friend,” the omohyoid muscle is the anatomic separation of nodal levels III and IV. It has also been used as a reliable landmark in the supraclavicular region, for endoscopic exploration of the brachial plexus.

Having a common primordium with the sternohyoid muscle, the omohyoid muscle often varies in shape and insertions. It usually has two bellies (anterior and posterior) and extends obliquely from the hyoid bone to the scapula.

In addition to this, its intermediate tendon can have variable relationship with the internal jugular vein. It always covers the inferior part of internal jugular vein, but several abnormalities have been reported. The omohyoid is the most frequently absent muscle of the infrahyoid group. It may occur only on one side, or it may be found as a single-bellied muscle; one belly is absent more frequently than both bellies; the inferior belly may be doubled, with the second belly possibly arising from the coracoid process. When the inferior belly is absent, the superior belly arises from the clavicle, and the resulting muscle is named cleidohyoideus.

The major arteries of the neck are: