ArticlesAnatomyHead and neckNeckInfrahyoid muscles

ArticlesAnatomyHead and neckNeckInfrahyoid muscles

Infrahyoid muscles

Author: Achudhan Karunaharamoorthy, MD • Reviewer: Dimitrios Mytilinaios, MD, PhD
Last reviewed: October 24, 2024
Reading time: 6 minutes

The infrahyoid muscles are a group of four paired muscles located in the anterior part of the neck and as the name suggest, inferior to the hyoid bone. They connect the hyoid bone to the sternum, larynx and scapula. The infrahyoid muscles include the omohyoid, sternothyroid, thyrohyoid and sternohyoid muscles.

This group of muscles, together with the suprahyoid muscle group, are important for several functions related to speech, swallowing and the movement of the larynx, by controlling the positioning of the hyoid bone.

Key facts about the infrahyoid muscles
Omohyoid	Origin: Inferior belly: Superior border of scapula, Superior belly: Intermediate tendon of omohyoid muscle Insertion: Inferior belly: Intermediate tendon of omohyoid muscle, Superior belly: Body of hyoid bone Innervation: Anterior rami of spinal nerves C1-C3 (via ansa cervicalis) Function: Depresses and draws hyoid bone posteriorly
Sternothyroid	Origin: Posterior surface of manubrium of sternum, costal cartilage of rib 1 Insertion: Oblique line of thyroid cartilage Innervation: Anterior rami of spinal nerves C1-C3 (via ansa cervicalis) Function: Depresses larynx
Sternohyoid	Origin: Manubrium of sternum, medial end of clavicle Insertion: Inferior border of body of hyoid bone Innervation: Anterior rami of spinal nerves C1-C3 (via ansa cervicalis) Function: Depresses hyoid bone (from elevated position)
Thyrohyoid	Origin: Oblique line of thyroid cartilage Insertion: Inferior border of body and greater horn of hyoid bone Innervation: Anterior ramus of spinal nerve C1 (via hypoglossal nerve) Function: Depresses hyoid bone, elevates larynx

Contents

Anatomy and supply
Functions
Infrahyoid muscles paralysis
Sources

+ Show all

Anatomy and supply

Namely, the four muscles of the infrahyoid group are the;

Omohyoid
Sternothyroid
Thyrohyoid
Sternohyoid

You can quickly recall the list of infrahyoid muscles at any time by using the mnemonic "TOSS" (Thyrohyoid, Omohyoid, Sternothyroid, Sternohyoid)

Omohyoid muscle

The omohyoid muscle is divided into a superior and inferior belly. The inferior belly originates at the superior border of scapula, ascends craniomedially and merges into an intermediate tendon at the height of the lateral cervical region. This tendon is connected to the carotid sheath which surrounds the neurovascular bundle (including the common carotid artery, internal jugular vein and vagus nerve). The superior belly then originates from the intermediate tendon and attaches to the body of the hyoid bone.

The omoyhyoid is innervated by the ansa cervicalis (C1-C3), which arises from the cervical plexus. It functions to depress and draw the hyoid bone posteriorly.

Sternothyroid muscle

The sternothyroid muscle originates from the posterior surface of the manubrium of the sternum, as well as the costal cartilage of rib 1 and inserts on the oblique line of thyroid cartilage. Therefore, the sternothyroid is the only hyoid muscle that does not directly attach to the hyoid bone. The sternothyroid lies in close relation to the capsule of the thyroid gland.

Like the omoyhyoid, the sternothyroid is also innervated by the ansa cervicalis (C1-C3), arising from the cervical plexus. It functions to depress the larynx.

Sternohyoid muscle

The sternohyoid muscle originates from the posterior surface of the manubrium of the sternum, as well as the posterior surface of the medial end of the clavicle and inserts on the inferior border of the body of the hyoid bone. The sternohyoid is the most superficial of all infrahyoid muscles.

Like the omohyoid and sternothyroid, the sternohyoid is also innervated by the ansa cervicalis (C1-C3), arising from the cervical plexus. It functions to depress the hyoid bone from an elevated position.

Thyrohyoid muscle

The thyrohyoid muscle constitutes the continuation of the sternothyroid, originating at the oblique line of thyroid cartilage and inserting on the inferior border of the body and greater cornu of the hyoid bone.

Unlike the rest of the infrahyoid muscles, the thyrohyoid muscle is not innervated by the ansa cervicalis, but rather by nerve fibers from the anterior ramus of spinal nerve C1, which reaches the muscle via the hypoglossal nerve (CN XII). The thyrohyoid has two functions. It is able to depresses the hyoid bone in conjunction with the other infrahyoid muscles, or it can elevate the larynx if the hyoid bone is stabilized by the suprahyoid muscles.

Functions

The infrahyoid muscles are responsible for the positioning of the hyoid bone along with the suprahyoid muscles. They play an active role in swallowing and the movement of the larynx. More specifically, all infrahyoid muscles (except the sternothyroid) depress the hyoid. The sternothyroid depresses the larynx whereas the thyrohyoid elevates it (when the hyoid bone is fixed). The omohyoid has an additional function due to its attachment to the carotid sheath: by pulling the sheath, it maintains a low pressure in the internal jugular vein, this way increasing the blood return from the head to the superior vena cava.

Learn more about the hyoid bone and muscles of the anterior neck with the following study units:

Infrahyoid muscles paralysis

Trauma in the region of the cervical spine can damage the ansa cervicalis, resulting in paresis or even paralysis of the infrahyoid muscles. Clinically, those may be presented as swallowing difficulties, a hoarse voice and throat tightness. Incorrect positioning during surgery or medical interventions in the cervical region can also lead to nerve injuries.

A common type of surgery in which the ansa cervicalis is often deliberately “sacrificed” is neck dissection. During that type of operation, which is indicated for malignant head and neck tumors, lymph nodes, fat tissue, muscles and even nerves and blood vessels are radically removed from the cervical region. Only the most important structures (e.g. carotid artery, vagus nerve, etc) are preserved.

Sources

All content published on Kenhub is reviewed by medical and anatomy experts. The information we provide is grounded on academic literature and peer-reviewed research. Kenhub does not provide medical advice. You can learn more about our content creation and review standards by reading our content quality guidelines.

References:

D. Drenckhahn/J. Waschke: Taschenbuch Anatomie, 1st edition, Urban & Fischer Verlag/Elsevier (2008), p. 185-186
W. Platzer: Taschenatlas Anatomie – Band 1 – Bewegungsapparat, 10th edition, Thieme Verlag (2009), p. 326-327
G. Boeck/U. Bommas-Ebert/T. Brandenburger et al.: Prüfungswissen Physikum, Thieme Verlag (2009), p. 242
R. Gautschi: Manuelle Triggerpunkt-Therapie, 2nd edition, Thieme Verlag (2013), p. 246-247
J. Siewert, M. Allgöwer: Chirurgie, 7th edition, Springer-Verlag (2001), p. 478
C. Kerawala/M. Heliotos: Prevention of complications in neck dissection, Head and Neck Oncology (2009), 1:35

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