The mylohyoid is the primary muscular floor of the mouth, forming a sling between the two mandibular bodies. It divides the submandibular space into the sublingual space above and the submandibular space proper below.
| Origin | Mylohyoid line of the mandible — entire length on the inner surface |
|---|---|
| Insertion | Hyoid body (anterior fibres) and median fibrous raphe (posterior fibres) |
| Nerve Supply | Mylohyoid nerve — branch of the inferior alveolar nerve (V3) |
| Blood Supply | Submental artery |
| Actions | Forms and elevates the floor of the mouth; Elevates the hyoid and tongue during swallowing and speech; Depresses the mandible when the hyoid is fixed |
|---|
The mylohyoid divides the submandibular space into sublingual (above) and submandibular (below) compartments — a distinction critical in Ludwig's angina management. Infection in the sublingual space above mylohyoid elevates the tongue and floor of mouth, while submandibular space infection below mylohyoid causes neck swelling. Both are airway emergencies.
The floor of mouth is inspected by asking the patient to lift the tongue — mylohyoid tone is assessed by bimanual palpation.
Submandibular space infection spreading above and below the mylohyoid producing bilateral submandibular and sublingual swelling with tongue elevation and airway compromise, requiring urgent surgical decompression.
