CorpusHuman Anatomy
MuscularMuscle group

Suprahyoid muscles

Musculi suprahyoidei

Also known as: suprahyoids, stylohyoid, geniohyoid

Four muscles above the hyoid (digastric, stylohyoid, mylohyoid and geniohyoid). They raise the hyoid and larynx in swallowing and depress the mandible.

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Overview

The suprahyoid muscles link the hyoid bone to the skull and mandible and form the floor of the mouth. If the hyoid is fixed by the infrahyoid muscles, they depress the mandible (opening the mouth against resistance, together with lateral pterygoid). If the mandible is fixed, they elevate the hyoid and larynx, which is an essential step in swallowing and protects the airway beneath the epiglottis.

Their innervation reflects their mixed embryological origin. Digastric (anterior belly) and mylohyoid come from the 1st arch and are supplied by the nerve to mylohyoid (V3). Stylohyoid and the posterior belly of digastric come from the 2nd arch and are supplied by CN VII. Geniohyoid comes from occipital somites and is supplied by C1 fibres travelling with the hypoglossal nerve.

Parts & subdivisions

  1. Digastric
    Two bellies joined by an intermediate tendon slung to the hyoid.
  2. Stylohyoid
    Styloid process → body of the hyoid. Its tendon splits around the digastric tendon. Supplied by CN VII. Elevates and retracts the hyoid.
  3. Mylohyoid
    Forms the muscular floor of the mouth (diaphragma oris).
  4. Geniohyoid
    Inferior mental spine → body of the hyoid. Supplied by C1 via CN XII. Pulls the hyoid forward and up, widening the pharynx.

Anatomy

Innervation

Nerve to mylohyoid (V3): anterior digastric and mylohyoid. Facial nerve (VII): posterior digastric and stylohyoid. C1 via the hypoglossal nerve: geniohyoid.

Nerve roots

CN V3, CN VII and C1

Arterial supply

Submental artery (facial), lingual artery, and posterior auricular and occipital arteries (posterior digastric).

Function

  • Elevate the hyoid and larynx during swallowing and speech
  • Depress the mandible when the hyoid is fixed
  • Support the floor of the mouth and the tongue

Clinical significance

Dysphagia and aspiration

Weak hyolaryngeal elevation after stroke or in head and neck cancer impairs closure of the epiglottis over the airway, causing aspiration. Swallowing therapy includes manoeuvres that train the suprahyoid muscles, such as Shaker head-lift exercises.

Compiled from standard anatomy and physiology references — see the Muscular System sources. For education only; not medical advice.