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The mylohyoid muscle has a long origin along the mylohyoid line of the mandible. As such it forms the muscular floor of the oral cavity. It inserts at the body of the hyoid and into the contralateral mylohyoid. It is innervated by a branch of cranial nerve V3 (trigeminal nerve – third division, mandibular nerve). Like the digastric it is capable of elevating the hyoid when swallowing if the mouth is closed. This is why the patients always want to close to swallow, usually at an inconvenient time. Though swallowing is possible with the mouth open it is much less effective. The mylohyoid also acts to depress the mandible if the infrahyoids are activated. The other effect one can easily demonstrate is that it raises the floor of the mouth. Just placing a finger behind the chin as one swallows will prove this.