Mentalis Muscle

Introduction:

The mentalis is a paired central muscle of the lower lip, situated at the tip of the chin.

It originates from the mentum and inserts into the chin soft tissue. The primary effect of the mentalis contraction is the upward-inward movement of the soft tissue complex of the chin, which raises the central portion of the lips in turn.

In the setting of lip incompetence (the upper and lower lips do not touch each other at rest), the mentalis muscle contraction can bring temporary but strained oral competence.

Definition and Location

• The mentalis muscle is classified as a facial muscle and it is located in the area between the tip of the chin and the lower lip.
• This muscle originates (starts) at the incisive fossa of the mandible (which is a depressed area in the chin area of the lower jaw) and travels upward and inserts (ends) in the skin of the lower lip.
• The mentalis muscle receives electrical impulses from the brain through the cranial nerve VII, which is also known as the facial nerve.
• The process of a muscle receiving electrical impulses from a nerve is called innervation.
• The mentalis muscle receives its blood supply from the facial artery.
• The facial artery is a small branch of the carotid artery, which is a very large blood vessel that runs up the neck and into the head/skull.

Origin and Insertion:

• Mentalis muscle originates from the incisive fossa of the mandible.
• Its short fibers descend inferiorly to insert into the skin of the chin, at the level of mentolabial sulcus.

Relation:

• The mentalis muscles lie on the mandible, on each side of the frenulum of the lower lip.
• The superolateral part of each muscle is covered by the depressor labii inferioris muscle, while the remainder of the mentalis muscle bellies is subcutaneous.

Innervation:

• Mentalis is innervated by the mandibular branch of facial nerve (CN VII).

Blood Supply:

• Inferior labial branch of the facial artery and the mental branch of the maxillary artery supply the mentalis muscle.

Function:

• Pullings its cutaneous attachment superiorly, the mentalis muscle elevates the base of the lower lip, thus everting and protruding it.
• This movement also wrinkles the skin of the chin.
• The function of these movements is to adjust the shape of the lips for drinking, as well as to express facial expressions associated with the emotions of sorrow, contempt, and doubt.

Clinical Importance

Geniospasm

A mentalis muscle movement problem caused by genetics is called geniospasm. The muscle is repeatedly contracted, and episodes can last anywhere from a few seconds to several hours.

It might be treated with some drugs, like benzodiazepines and haloperidol.
Botulinum toxin injections that paralyze the muscle permanently might be more efficient.

Cosmetics

In order to lessen chin wrinkles, the mentalis muscle may be temporarily paralyzed with botulinum toxin. This could be carried out for aesthetic reasons.

Other images of the Mentalis muscle:

FAQ