Mentalis muscle
Musculus mentalis
The mentalis is a small, cone-shaped muscle at the point of the chin that raises and pushes out the lower lip, as in pouting.
At a glance
- English
- Mentalis muscle
- Latin (TA2)
- Musculus mentalis
- System
- Muscle
- Region
- Head
- Side
- Paired, left and right
About the mentalis muscle
The mentalis is a paired muscle of facial expression at the point of the chin, one on each side of the midline. The two lie close together in front of the mandibular symphysis, deep to the lower lip and medial to the depressor labii inferioris. It is the only muscle that elevates the lower lip, and because of the expression it produces it is sometimes called the pouting muscle.
Unlike most lip muscles, it runs from bone to skin rather than into the lip itself. It arises from the incisive fossa of the mandible, a small hollow just below the roots of the lower incisors and close to the midline above the mental protuberance. Its fibres pass downwards and forwards in a cone, ending in the skin of the chin. Between the two muscles there is often a small gap, which can show on the surface as a chin dimple or cleft.
Its contraction is weak but distinctive. It pulls the soft tissues of the chin upwards and inwards, which lifts the central part of the lower lip and pushes it forwards; with orbicularis oris acting on the upper lip, this lets the lips pout. On the surface it wrinkles and puckers the skin of the chin, as in expressions of doubt, displeasure or the start of crying. In people whose lips do not meet at rest, the mentalis may contract to bring them together, giving a strained look and a knobbly chin. Its nerve is the facial nerve's marginal mandibular branch, and its blood comes from the mental and inferior labial arteries.
Its thickness and activity can be measured readily with ultrasound. Geniospasm is a rare inherited disorder in which the mentalis contracts repeatedly in bouts that may last from seconds to hours; it may be treated with medicines or, more reliably, with botulinum toxin. The same toxin is also used cosmetically to smooth a dimpled, puckered chin.
Attachments, action and supply
- Origin
- Incisive fossa of the mandible, below the lower incisors.
- Insertion
- Skin of the chin.
- Action
- Raises and protrudes the lower lip and wrinkles the skin of the chin.
- Nerve supply
- Facial nerve (VII), marginal mandibular branch.
- Blood supply
- Mental artery and the inferior labial branch of the facial artery.
Anthromica
See the mentalis 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.
