Sternohyoid muscle

Sternohyoid muscle is one of the superficial infrahyoid (strap) muscles, located on either side of the midline in the anterior neck.

Anatomical details

1. Origin

• Posterior surface of the manubrium of sternum

• Medial end of the clavicle

• Posterior sternoclavicular ligament

2. Insertion

• Inferior border of the body of the hyoid bone (medial to the insertion of omohyoid muscle)

Innervation

The sternohyoid muscle is innervated by branches from the anterior rami of C1 to C3 spinal nerves, which form the ansa cervicalis.

• The ansa cervicalis is a nerve loop derived from the cervical plexus (C1–C3) that lies on the anterior surface of the carotid sheath. It supplies motor innervation to most infrahyoid muscles, including the sternohyoid, sternothyroid, and omohyoid.

Actions

• Depresses the hyoid bone after its elevation during swallowing or tongue movements.

• Helps stabilize the hyoid bone to facilitate laryngeal and tongue movements.

Relations

• The sternohyoid muscle lies superficial to sternothyroid and thyrohyoid muscles. It is covered by investing layer of deep cervical fascia.

• The superior belly of omohyoid lies lateral to sternohyoid muscle.