Dominic Stone
The omohyoid muscle is a long, thin muscle in the neck that consists of two bellies, superior and inferior, joined by an intermediate tendon. It is an infrahyoid muscle that facilitates speech and swallowing by depressing the hyoid bone and larynx and reestablishing breathing. The omohyoid muscle also maintains a low pressure in the internal jugular vein by tensing the carotid sheath.
| Characteristics | Values |
|---|---|
| Muscle type | Infrahyoid muscle |
| Muscle structure | Consists of superior and inferior bellies joined by an intermediate tendon |
| Muscle function | Depresses the hyoid bone and larynx, facilitates speech and swallowing, maintains low pressure in the internal jugular vein |
| Innervation | Ansa cervicalis of the cervical plexus |
| Blood supply | Superior thyroid artery (branch of the external carotid artery) and inferior thyroid artery (branch of the thyrocervical trunk) |
| Clinical relevance | Surgical landmark for neck dissections and identification of the internal jugular vein |
| Variability | Variations in number, attachments, and position observed in cadaver studies |
| Attachments | Originates from the scapula and inserts into the hyoid bone, with attachments to the clavicle and sternohyoid muscle |
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What You'll Learn
The omohyoid muscle is an infrahyoid muscle of the neck
The omohyoid muscle has several functions. Its primary function is to depress and fix the hyoid bone and underlying larynx, drawing them downwards in phonation and the terminal phase of swallowing. This action also facilitates breathing following the act of swallowing. Additionally, the omohyoid muscle maintains a low pressure in the internal jugular vein by tensing the carotid sheath. This action helps control the bodily response to extended inspiratory activity, reducing the likelihood of soft tissues compressing the great vessels and lung apices.
The omohyoid muscle is innervated by the ansa cervicalis of the cervical plexus, receiving fibres from the ventral rami of C1-C3 spinal nerves. The superior belly is innervated by the superior root of ansa cervicalis (C1), while the inferior belly receives fibres from spinal nerves C1, C2, and C3. The omohyoid receives its arterial blood supply from the superior thyroid artery, a branch of the external carotid artery, and the inferior thyroid artery, a branch of the thyrocervical trunk.
The omohyoid muscle is important in neck dissections as it serves as a surgical landmark for level III and IV lymph node metastases. Variations in the structure of the omohyoid have been observed in cadaver studies, including the presence of a double omohyoid, variations in the origin of the inferior belly, and the absence of the superior or inferior belly. The omohyoid is also clinically significant in the treatment of omohyoid syndrome, where trigger point injections into the inferior belly of the muscle can provide pain relief.
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It consists of superior and inferior bellies
The omohyoid muscle is an infrahyoid muscle of the neck that consists of superior and inferior bellies, joined by an intermediate tendon. The superior belly arises from the hyoid bone, while the inferior belly arises from the scapula. The intermediate tendon is variable in length and form and is anchored to the clavicle and first rib by a band of deep cervical fascia.
The omohyoid muscle is innervated by the ansa cervicalis of the cervical plexus, receiving fibres from the ventral rami of C1-C3 spinal nerves. The superior belly is innervated by the superior root of ansa cervicalis (C1), while the inferior belly receives fibres from spinal nerves C1, C2 and C3. The muscle is supplied by the superior thyroid artery, a branch of the external carotid artery, and the inferior thyroid artery, a branch of the thyrocervical trunk.
The omohyoid muscle has several important functions. Its primary role is to depress and fix the hyoid bone and underlying larynx, which facilitates speech and swallowing. Additionally, it plays a role in maintaining low pressure in the internal jugular vein by tensing the carotid sheath. This helps to regulate venous return from the head to the superior vena cava. The omohyoid muscle is also significant in neck dissections, serving as a surgical landmark for level III and IV lymph node metastases.
Variations in the structure of the omohyoid muscle have been observed, particularly in the origin and attachment of the superior and inferior bellies. In some cases, the superior belly may be attached to the transverse process of the C6 vertebra or merge with the sternohyoid muscle. The inferior belly may originate from the clavicle or be absent altogether. Understanding these variations is crucial due to the muscle's close relationship with large vessels and the brachial plexus.
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It is involved in depressing the hyoid bone and larynx
The omohyoid muscle is an infrahyoid muscle of the neck. It is a long, thin muscle that consists of two bellies, superior and inferior, joined by an intermediate tendon. The superior belly arises from the hyoid bone, and the inferior belly arises from the scapula. The intermediate tendon is anchored to the clavicle by the deep cervical fascia.
The omohyoid muscle is involved in depressing the hyoid bone and larynx. This means it draws the hyoid bone and underlying larynx downwards in phonation and the terminal phase of swallowing. This is one of the ways in which the omohyoid facilitates speech and swallowing.
The omohyoid also has a role in maintaining low pressure in the internal jugular vein. By contracting, it pulls on the carotid sheath and tenses the cervical fascia, thereby lessening the likelihood of inward suction of soft tissues that would compress the great vessels and lung apices.
The hyoid bone is important for speech and swallowing. It is a small, U-shaped bone in the neck that sits just above the Adam's apple and below the jaw. The hyoid bone provides attachment for the tongue and various muscles, including the omohyoid, which help to move the hyoid bone during speech and swallowing.
The larynx, or voice box, is a tube-shaped organ in the neck that plays a vital role in breathing, speech, and swallowing. The larynx houses the vocal cords, which vibrate to produce sound for speech. During swallowing, the larynx rises to close off the trachea and prevent food or liquid from entering the airway.
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It is innervated by the ansa cervicalis of the cervical plexus
The omohyoid muscle is located in the anterior region of the neck and is one of the group of muscles known as the infrahyoid muscles. The omohyoid is innervated by the ansa cervicalis of the cervical plexus, which arises from the cervical plexus. The cervical plexus is a network of nerves in the neck that supply the head, neck, and shoulder. The ansa cervicalis is a loop of nerves that originates from the cervical plexus and supplies the infrahyoid muscles, including the omohyoid.
The omohyoid muscle itself has two bellies, superior and inferior, which are connected via an intermediate tendon. The superior belly is attached to the hyoid bone, while the inferior belly is attached to the scapula. The intermediate tendon is anchored to the clavicle and first rib by a fascial sling. The innervation of the omohyoid muscle by the ansa cervicalis is important for its function. The inferior belly of the omohyoid muscle is innervated by the ansa cervicalis itself, which receives fibres from the cervical spinal nerves C1-C3. The superior belly, on the other hand, is innervated by the superior root of the ansa cervicalis, which arises from the first cervical spinal nerve (C1).
The omohyoid muscle plays a crucial role in depressing the hyoid bone and larynx, as well as reestablishing breathing after swallowing. It also facilitates speech and controls the bodily response to extended inspiratory activity. Additionally, the omohyoid muscle helps maintain a low pressure in the internal jugular vein by contracting and pulling on the carotid sheath, thereby increasing venous return to the superior vena cava. The contraction of the omohyoid muscle has a direct effect on the lumen of the internal jugular vein due to its direct adhesion to the anterior wall of this vessel.
The omohyoid muscle is also important in neck dissections as it serves as a surgical landmark for level III and IV lymph node metastases. Furthermore, the omohyoid is useful in locating the suprascapular nerve when it is difficult to find as they run closely together from the lateral neck towards the scapular notch. Overall, the innervation of the omohyoid muscle by the ansa cervicalis of the cervical plexus is essential for its various functions and roles in the anatomy of the neck.
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The omohyoid muscle is important in neck dissections
The omohyoid muscle is a long, thin muscle in the neck that consists of superior and inferior bellies and an intermediate tendon. The muscle is important in neck dissections because it is the surgical landmark for level III and IV lymph node metastases.
The omohyoid is an infrahyoid muscle that facilitates speech and swallowing. It is innervated by the ansa cervicalis of the cervical plexus, receiving fibres from the ventral rami of C1-C3 spinal nerves. The superior belly of the omohyoid muscle is innervated by the superior root of ansa cervicalis (C1), while the inferior belly receives fibres from spinal nerves C1, C2 and C3.
The omohyoid muscle's primary function is to depress and fix the hyoid bone and underlying larynx, though it also draws the hyoid bone downwards in phonation and in the terminal phase of swallowing. The muscle also maintains a low pressure in the internal jugular vein by tensing the carotid sheath. This helps to increase venous return from the head to the superior vena cava.
The omohyoid muscle is also important in neck dissections as it can be used to identify the internal jugular vein immediately underneath. The muscle's contraction can cause dilatation of the penetrating neck veins, which may lead to the creation of an air embolus after trauma or surgery in this region.
The omohyoid muscle is also significant in neck dissections due to its close relation to the large vessels and brachial plexus. The needle should be advanced slowly and carefully to avoid encountering the brachial plexus, and the patient should be warned that a paresthesia could occur.
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Frequently asked questions
The omohyoid is an infrahyoid muscle in the neck. It consists of two bellies—superior and inferior—joined by an intermediate tendon.
The omohyoid muscle's primary function is to depress the hyoid bone and underlying larynx. It also draws the hyoid bone downwards during speech and in the terminal phase of swallowing.
The omohyoid muscle facilitates swallowing by depressing the hyoid bone and reestablishing breathing after the act of swallowing.
The omohyoid muscle aids in speech by drawing the hyoid bone and underlying larynx downwards during phonation.
The intermediate tendon of the omohyoid muscle lies over and slides easily on the internal jugular vein. By contracting, the omohyoid muscle maintains a low pressure in the internal jugular vein, increasing venous return from the head to the superior vena cava.
