Sternohyoid Muscle Anatomy

The sternohyoid muscle belongs to the infrahyoid muscle group, presenting as a pair of thin, ribbon-like muscles situated in the anterior neck region. This muscle exhibits a vertical orientation, extending from its inferior attachment at the sternum to its superior attachment at the hyoid bone. Its position anterior to the sternothyroid muscle and deep to the investing layer of deep cervical fascia makes it an important surgical landmark.

Sternohyoid Muscle Anatomy

The sternohyoid muscle originates from multiple points, including the posterior surface of the manubrium sterni, the medial end of the clavicle, and occasionally the first costal cartilage. The muscle fibers course superiorly in a nearly vertical fashion before inserting into the inferior border of the body of the hyoid bone. This anatomical arrangement facilitates its primary function of hyoid bone depression.

Innervation of the sternohyoid muscle occurs through the superior rami of the ansa cervicalis, specifically derived from the first three cervical nerves (C1-C3). The muscle receives its blood supply primarily from the superior thyroid artery, with additional contributions from the inferior thyroid artery.

See Also: Brachial Plexus Anatomy Overview – Easy Tutorial

The sternohyoid muscle serves multiple physiological functions in the anterior neck region. Its primary action involves depression of the hyoid bone, which plays a crucial role during the pharyngeal phase of swallowing. Additionally, the muscle assists in laryngeal depression and stabilization during phonation. When acting bilaterally, it contributes to neck flexion, particularly when the hyoid bone is fixed.

The sternohyoid muscle may vary in size, length, and thickness in different individuals. The origins and attachments of the sternohyoid may also vary slightly. In some cases, the sternohyoid was found to be one muscle instead of a paired muscle. The sternohyoid muscle has also been found to originate from the omohyoid muscle’s tendon instead of the sternum. Interestingly, some individuals completely lack the presence of the sternohyoid muscle. 

Clinical Significance

During thyroid surgery, the muscle often requires lateral retraction or occasional division to access the thyroid gland. In cases of anterior neck trauma or during emergency cricothyroidotomy procedures, the muscle serves as an important surgical landmark. Furthermore, dysfunction of this muscle may contribute to swallowing disorders and voice alterations.

Recent research has highlighted the sternohyoid muscle’s role in obstructive sleep apnea and its potential involvement in novel therapeutic approaches. Understanding the muscle’s molecular composition and mechanistic properties continues to evolve, offering new insights into its clinical significance.

On cross-sectional imaging, particularly CT and MRI, the sternohyoid muscle appears as a paired, symmetric structure in the anterior neck. Medical professionals should familiarize themselves with its normal radiological appearance to accurately identify pathological conditions affecting this region.

References & More

1. Clinically Oriented Anatomy, 8th Edition https://www.lww.com/moore-clinically-oriented-anatomy
2. Nguyen JD, Duong H. Anatomy, Head and Neck, Sternohyoid Muscle. [Updated 2023 Jul 24]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-. Available from: Pubmed