Sternothyroid muscle
Musculus sternothyreoideus
- Latin synonym: Musculus sternothyroideus
- Related terms: Sternothyroid; Omohyoid (Superior belly); Omohyoid: Superior belly
Definition
Sternothyroid muscle | |
Origin | Manubrium |
Insertion | Thyroid cartilage |
Innervation | Ventral rami of C1 to C3 (via ansa cervicalis) |
Action | Draws the thyroid cartilage inferiorly, thereby lowering the larynx. |
Sternothyroid muscle is a deep infrahyoid muscle situated in the anterior neck, lying deep to the sternohyoid and extending from the sternum to the thyroid cartilage.
Anatomical details
1. Origin
Posterior surface of the manubrium of the sternum and the posterior border of the first costal cartilage
2. Insertion
Oblique line of the lamina of the thyroid cartilage
Innervation
The sternothyroid 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.
Action
Depresses the larynx by drawing the thyroid cartilage downward after elevation during swallowing or vocalization.
Relations
The sternothyroid muscle lies deep to the sternohyoid and superficial to the thyroid gland. The thyrohyoid muscle continues upward from its insertion.
References
Gray, H. (2016) Gray’s Anatomy: The Anatomical Basis of Clinical Practice. 41st edn. Edited by S. Standring. New York: Elsevier. Chapter 29: Neck, pp. 448-450.
