Neck

Infrahyoids

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Overview


The suprahyoid muscles are a collection of four paired muscles, situated inferior to the hyoid bone. Collectively, they act to depress the larynx (either directly or indirectly via acting on the hyoid) and aid in phonation. They can also ‘fix’ the hyoid bone, allowing digastric & geniohyoid to depress the mandible.


Gross Anatomy


Sternohyoid

Origin

Postero-superior aspect of manubrium and adjacent sternoclavicular joint & clavicle

Insertion

Lower border of the hyoid body

Nerve

Ansa Cervicalis (C1,2,3)

Action

Depresses hyoid and, therefore, larynx

 

Omohyoid

Origin

Inferior belly arises from upper border of scapula & associated transverse scapular ligament

Insertion

Superior belly inserts lateral to sternothyroid on lower border of the hyoid body

Nerve

Ansa Cervicalis (C1,2,3)

Action

Depresses hyoid and, therefore, larynx

Notes

Two bellies meet to form an intermediate tendon where they overlie the internal jugular vein. This passes through a fibrous ‘sling’ in the investing layer of the deep cervical fascia

 

Sternothyroid

Origin

Posterior aspect of manubrium, deep to sternohyoid

Insertion

Oblique line of the thyroid cartilage

Nerve

Ansa Cervicalis (C1,2,3)

Action

Directly depresses larynx

 

Thyrohyoid

Origin

Lower border of the hyoid body, deep to sternohyoid and omohyoid

Insertion

Oblique line of the thyroid cartilage, alongside sternothyroid

Nerve

C1 fibres travelling with Hypoglossal nerve (CN XII)

Action

Can either elevate larynx or depress hyoid


Clinical Anatomy




Quick Anatomy


Key Facts

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Aide-Memoire

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Summary


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References


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