Omohyoid Muscle Anatomy

The omohyoid muscle presents as a unique digastric muscle consisting of superior and inferior bellies connected by an intermediate tendon. The muscle’s distinctive appearance and position make it an essential landmark during neck surgeries and clinical examinations.

Omohyoid Muscle Anatomy

The omohyoid muscle demonstrates complex fascial relationships within the anterior neck region. The superior belly originates from the hyoid bone’s lower border, while the inferior belly originates from the superior border of the scapula, specifically near the suprascapular notch.

See Also: Clavicle Anatomy | Bone & Muscles

It travels obliquely across the neck, deep to the sternocleidomastoid muscle but superficial to the internal jugular vein and common carotid artery. The intermediate tendon, where the two bellies meet, is bound to the clavicle by a fascial sling derived from the investing layer of deep cervical fascia. This architectural arrangement contributes to the muscle’s functional capabilities and clinical significance.

The inferior belly of the omohyoid muscle can just barely be seen and palpated as it passes superomedially across the inferior part of the lateral cervical region. Easiest to observe in thin people, the omohyoid muscle can often be seen contracting when they are speaking.

Understanding the neurovascular supply of the omohyoid muscle is crucial for surgical procedures and clinical interventions. The superior belly receives innervation from the superior root of the ansa cervicalis (C1), while the inferior belly is innervated by the inferior root (C1, C2, C3). The muscle’s blood supply primarily derives from branches of the superior thyroid artery for the superior belly and the suprascapular artery for the inferior belly.

See Also: Brachial Plexus Anatomy Overview – Easy Tutorial

The omohyoid muscle serves multiple physiological functions in the neck region. Its primary action involves depression of the hyoid bone during swallowing and speaking. Additionally, the muscle plays a role in maintaining the patency of the internal jugular vein during respiration by preventing collapse during rapid inspiratory movements, this function is done because of its attaching to the carotid sheath. This function becomes particularly significant during conditions affecting venous return from the head and neck.

Anatomical variations of the Omohyoid muscle may include absence of one or both bellies, duplication of the muscle, or alterations in its attachment points. Such variations can impact surgical planning and clinical outcomes, making preoperative imaging and careful dissection crucial.

Clinical Implications

From a clinical perspective, the omohyoid muscle holds significant importance in various medical scenarios. During neck dissections, the muscle serves as a crucial surgical landmark, helping surgeons navigate through complex neck anatomy. The muscle’s relationship with the internal jugular vein and common carotid artery makes it an important reference point during vascular access procedures and neck explorations.

References & More

1. Gray’s Anatomy: The Anatomical Basis of Clinical Practice, 42nd Edition https://www.elsevier.com/books/grays-anatomy/standring/978-0-7020-7710-5
2. Rai R, Ranade A, Nayak S, Vadgaonkar R, Mangala P, Krishnamurthy A. A study of anatomical variability of the omohyoid muscle and its clinical relevance. Clinics (Sao Paulo). 2008 Aug;63(4):521-4. doi: 10.1590/s1807-59322008000400018. PMID: 18719765; PMCID: PMC2664130. Pubmed