Infrahyoid Muscles
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Introduction
Infrahyoid muscles are also known as “strap muscles” which connect the hyoid, sternum, clavicle and scapula. They are located below the hyoid bone on the anterolateral surface of the thyroid gland and are involved in movements of the hyoid bone and thyroid cartilage during vocalization, swallowing and mastication. They are composed of four paired muscles, organized into two layers as following:[1][2][3][4][5][6]
- Superficial layer
- Deep layer
Superficial layer
The superficial layer consists of the following muscles:[2]
- Sternohyoid
- Omohyoid
Sternohyoid
It is a thin, narrow strap and lies anterior to the remaining strap muscles and the thyroid gland.
Origin
It originates from the posterior surface of the medial end of the clavicle, the posterior sternoclavicular ligament and the upper posterior aspect of the manubrium sterni.
Insertion
It inserts at the inferior border of the body of the hyoid bone.
Nerve Supply
It is innervated by branches of ansa cervicalis (C1, C2, and C3).
Arterial Supply
It arterial supply comes from the branches of the superior thyroid artery.
Action
It depresses the hyoid bone after it has been elevated.
Variation
It may be absent or double, augmented by clavicle slip (cleidohyoid), or interrupted by a tendinous intersection.[1][2]
Omohyoid
The omohyoid muscle is found deep in the sternocleidomastoid and consists of two bellies (superior and inferior) united at an angle by an intermediate tendon.
Superior Belly
Origin:
It begins at the intermediate tendon.
Insertion:
It inserts into the lower border of the hyoid bone.
Nerve Supply:
It is innervated by the superior ramus of the ansa cervicalis and from hypoglossal nerve.
variation
It can be absent or double; It is sometimes fused with sternohyoid.
Inferior Belly
Origin:
It arises from the upper border of the scapula near the scapular notch and occasionally from the superior transverse scapular ligament.
Insertion:
It inserts into the intermediate tendon.
Nerve Supply:
It is supplied by ansa cervicalis (C1, C2 and C3).
Variation:
It can be absent or double; it may be attached directly to the clavicle.
Arterial Supply:
It is supplied by the superior thyroid and lingual arteries.
Action:
- It depresses the hyoid bone after it has been elevated.
- It tenses the lower part of the deep cervical fascia in prolonged inspiratory effort, reducing the tendency for soft parts to be sucked inward.[1][2]
Deep layer
The deep layer consists of the following muscles:[2]
- Sternothyroid
- Thyrohyoid
Sternothyroid
It is shorter and wider than the sternohyoid and contacts the anterior surface of the thyroid gland.
Origin:
It arises from the posterior surface of the manubrium sterni and the posterior edge of the first rib.
Insertion:
It inserts into the oblique line of the thyroid cartilage.
Nerve Supply:
It is innervated by branches of ansa cervicalis.
Arterial Supply:
It is supplied by the superior thyroid and lingual arteries.
Action:
- It draws the larynx downwards after it has been elevated by swallowing or vocal movements.
- In low notes singing, this downward traction would be exerted with hyoid bone relatively fixed.
Variation:
An accessory belly can be present.[1][2][7]
Thyrohyoid
It is a small quadrilateral muscle that may be regarded as an upward continuation of the sternothyroid muscle.
Origin:
The oblique line on the lamina of the thyroid cartilage.
Insertion:
It attaches to the lower border of the greater cornu and adjacent part of the body of the hyoid bone.
Innervation:
It is innervated by fibres of the first cervical spinal nerve which branches of the hypoglossal nerve beyond the descendance hypoglossi.
Arterial Supply:
It is supplied by the superior thyroid and lingual arteries.
Action
- It depresses the hyoid bone.
- When the high notes are sung, the thyrohyoid muscle pulls the larynx upwards with the hyoid bone stabilized.[1][2]
see this video for further explanation
Clinical Relevance
Infrahyoid muscle paralysis: Trauma to the cervical spine can cause damage to the ansa cervicalis which in turn can result in paresis or paralysis of the infrahyoid muscles. Difficulty in swallowing, hoarseness in the voice or throat tightness can be present as a manifestation of the injury.[5]
Omohyoid Syndrome: It is a rare condition in which X- -shaped neck mass protrudes laterally on swallowing. It is caused when the omohyoid muscle displaces the sternocleidomastoid muscle that lies on the top of it.[9][10][11]
Sternohyoid Syndrome: Laterally protruded mass is present similar to the omohyoid syndrome except the problematic muscle is sternohyoid and the mass has a different aspect when swallowing and at rest.[12]
Resources
References
- ↑ 1.0 1.1 1.2 1.3 1.4 Allen E, Fingeret A. Anatomy, head and neck, thyroid. StatPearls [Internet]. 2021 Jul 26.
- ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 Gray's anatomy : the anatomical basis of clinical practice. 2005. Neck. Muscles.
- ↑ Quadros LS, Bhat N, Babu A, D’souza AS. Anatomical variations in the ansa cervicalis and innervation of infrahyoid muscles. Int J Anat Res. 2013 Sep;1(2):69-74.
- ↑ Suzuki M, Sasaki M, Kamata K, Nakayama A, Shibamoto I, Tamada Y. Swallowing pattern classification method using multichannel surface EMG signals of suprahyoid and infrahyoid muscles. Advanced Biomedical Engineering. 2020;9:10-20.
- ↑ 5.0 5.1 Mnatsakanian A, Al Khalili Y. Anatomy, Head and Neck, Thyroid Muscles. StatPearls [Internet]. 2021 Jul 29.
- ↑ Fitzpatrick TH, Siccardi MA. Anatomy, Head and Neck, Adam's Apple. StatPearls [Internet]. 2021 Apr 14.
- ↑ Kang, Dong Wan, et al. “An Accessory Belly of the Sternothyroid Muscle on the Anterior Neck.” Surgical and Radiologic Anatomy, vol. 37, no. 2, 17 Apr. 2014, pp. 215–217, Accessed 2 Feb. 2022.
- ↑ Dr Matt & Dr Mark. Infrahyoid Muscles. Available from: http://www.youtube.com/watch?v=gbedi92HL6U [last accessed 30/12/2024]
- ↑ Lee AD, Yu A, Young SB, Battaglia PJ, Ho CJ. Omohyoid muscle syndrome in a mixed martial arts athlete: a case report. Sports Health. 2015 Sep;7(5):458-62.
- ↑ Ye B. Omohyoid muscle syndrome: report of a case. Chinese Medical Journal. 1980;93(01):65-8.
- ↑ Wong DS, Li JH. The omohyoid sling syndrome. American journal of otolaryngology. 2000 Sep 1;21(5):318-22.
- ↑ Kim JS, Hong KH, Hong YT, Han BH. Sternohyoid muscle syndrome. American journal of otolaryngology. 2015 Mar 1;36(2):190-4.