The mylohyoid forms the muscular floor of the mouth, creating the diaphragm on which the tongue rests and through which structures of the submandibular space are separated from the submental space. Its role in elevating the floor of the mouth during the oral phase of swallowing initiates the propulsive wave that moves the food bolus toward the pharynx. Abscesses in the submandibular space can spread through or around the mylohyoid into the floor of the mouth, producing Ludwig angina.
| Origin | Mylohyoid line of the mandible, running from the third molar region to the symphysis menti |
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| Insertion | Hyoid bone body (posterior fibres) and a median fibrous raphe (anterior fibres) |
| Nerve Supply | Mylohyoid nerve (branch of the inferior alveolar nerve, CN V3) |
| Blood Supply | Submental artery |
| Actions | Elevates the floor of the mouth and the hyoid during swallowing; Depresses the mandible when the hyoid is fixed; Forms the muscular floor of the oral cavity |
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By contracting it simultaneously raises the floor of the mouth, elevates the hyoid, and assists the tongue in pushing the food bolus posteriorly during swallowing, making it the primary muscle of the oral phase of deglutition.
Ludwig angina is a rapidly spreading bilateral cellulitis of the submandibular, sublingual, and submental spaces separated by the mylohyoid that can cause life-threatening airway obstruction. The mylohyoid raphe creates a point of relative weakness where dental abscesses from lower molar roots that extend below the mylohyoid line can spread into the neck rather than remaining in the oral cavity.
The mylohyoid is palpable as the taut floor of the mouth when the examiner places a finger under the chin and the patient tries to press the tongue to the roof of the mouth, creating the muscular platform between the mandible and the hyoid.
Rare rupture from a direct blow to the floor of the mouth or a very forceful bite, producing submental swelling and dysphagia, managed conservatively unless complicated by haematoma causing airway compromise.
