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Mylohyoid nerve
Just before entering the mandibular canal the inferior alveolar nerve gives off a motor
branch known as the mylohyoid nerve. The inferior alveolar nerve travels along with the
inferior alveolar artery and vein within the mandibular canal and divides into the mental
and incisive nerve branches at the mental foramen. The inferior alveolar nerve provides
sensation to the mandibular posterior teeth. The mylohyoid nerve pierces the sphenomandibular ligament and runs inferiorly and anteriorly in the mylohyoid groove and then
onto the inferior surface of the mylohyoid muscle. The mylohyoid nerve serves as an efferent nerve to the mylohyoid muscle and the anterior belly of the digastric muscle. This
nerve may in some cases also serve as an afferent nerve for the mandibular first molar.
The mylohyoid muscle is an anterior suprahyoid muscle that is deep to the digastric muscle. In addition to either elevating the hyoid bone or depressing the mandible, the muscle
also forms the floor of the mouth and helps elevate the tongue.
Note: The sublingual gland is located superior to the mylohyoid muscle.
Notes
1. When placing the film for a periapical view of the mandibular molars, it is
the mylohyoid muscle that gets in the way if it is not relaxed.
2. When the floor of the mouth is lowered surgically, the mylohyoid and genioglossus muscles are detached.
3. An injection into the parotid gland (capsule) when attempting to administer
an inferior nerve block may cause a Bell's palsy facial expression ⎯ paralysis
of the forehead muscles, the eyelid and of the upper and lower lips on the same
side of the face that the injection was given. Important: If the parotid capsule
injection happens, care must be taken to protect the eye from injury and drying
using lubrication and an eye patch.
4. Remember: The bone of the maxilla is more porous than that of the
mandible, therefore, it can be infiltrated anywhere.