Geniohyoid muscle
Musculus geniohyoideus
Geniohyoid is a narrow strap muscle in the floor of the mouth, running from the back of the chin to the hyoid bone.
At a glance
- English
- Geniohyoid muscle
- Latin (TA2)
- Musculus geniohyoideus
- System
- Muscle
- Region
- Neck
- Side
- Paired, left and right
About the geniohyoid muscle
Geniohyoid is a short, narrow muscle in the floor of the mouth. Its name records its two attachments: the chin (genio-) and the hyoid. It lies just above mylohyoid, on either side of the midline, touching its partner from the other side, and below genioglossus, the large tongue muscle that springs from the same region of the chin. It is one of the suprahyoid group of muscles.
The muscle begins at the inferior mental spine, a small bony point on the back of the mandible at the symphysis. It runs backwards and a little downwards and widens as it goes, to end on the front of the hyoid body. It is sometimes fused with its partner or doubled, and slips may pass to the greater horn of the hyoid or to genioglossus.
With the mandible fixed, geniohyoid pulls the hyoid forwards and upwards. This carries the tongue with it and widens the airway behind the tongue, so the muscle helps keep the pharynx open during breathing, especially in sleep. In the first stage of swallowing it works with mylohyoid and the anterior bellies of digastric to lift the hyoid and tongue as the food is pushed back into the pharynx. When the hyoid is held still from below, it helps open the mouth.
Its nerve supply is unusual. Fibres from the first cervical spinal nerve join the hypoglossal nerve for a short distance and leave it to reach geniohyoid, so the muscle is served by C1, not by the hypoglossal itself. Blood comes from the lingual artery, mainly its sublingual branch. Because it supports the tongue and airway, it is of interest in the study of obstructive sleep apnoea and of swallowing problems.
Attachments, action and supply
- Origin
- Inferior mental spine on the inner surface of the mandibular symphysis.
- Insertion
- Front of the hyoid body.
- Action
- Pulls the hyoid and tongue forwards and upwards, widening the upper airway; helps depress the mandible when the hyoid is fixed.
- Nerve supply
- C1 fibres carried by the hypoglossal nerve.
- Blood supply
- Lingual artery, chiefly its sublingual branch.
Anthromica
See the geniohyoid muscle where it really sits, with every layer of the body around it.
- Every layer, one body. Peel from muscle to bone, nerve, vessel and organ, and turn it any way.
- English and Latin. Every structure named the way your exam names it.
- Quiz until it sticks. Short drills on the structures you keep missing.
Free to start. No card.
