Sternothyroid muscle

The Sternothyreoideus (or Sternothyroid muscle) is shorter and wider than the Sternohyoideus, beneath which it is situated.

It arises from the posterior surface of the manubrium sterni, below the origin of the Sternohyoideus, and from the edge of the cartilage of the first rib, and sometimes that of the second rib, it is inserted into the oblique line on the lamina of the thyroid cartilage.

This muscle is in close contact with its fellow at the lower part of the neck, but diverges somewhat as it ascends; it is occasionally traversed by a transverse or oblique tendinous inscription.

Variations
Doubling; absence; accessory slips to Thyreohyoideus, Inferior constrictor, or carotid sheath.