The mental foramen is one of two

foramina In anatomy and osteology, a foramen (;Entry "foramen"
in

(openings) located on the anterior surface of the

mandible In anatomy, the mandible, lower jaw or jawbone is the largest, strongest and lowest bone in the human facial skeleton. It forms the lower jaw and holds the lower teeth in place. The mandible sits beneath the maxilla. It is the only movable bone ...

. It is part of the

mandibular canal In human anatomy, the mandibular canal is a canal within the mandible that contains the inferior alveolar nerve, inferior alveolar artery, and inferior alveolar vein. It runs obliquely downward and forward in the ramus, and then horizontally f ...

. It transmits the terminal branches of the

inferior alveolar nerve The inferior alveolar nerve (IAN) (also the inferior dental nerve) is a branch of the mandibular nerve, which is itself the third branch of the trigeminal nerve. The inferior alveolar nerves supply sensation to the lower teeth. Structure The in ...

and the mental vessels.

Structure

The mental foramen is located on the anterior surface of the

. It is directly below the commisure of the

lips The lips are the visible body part at the mouth of many animals, including humans. Lips are soft, movable, and serve as the opening for food intake and in the articulation of sound and speech. Human lips are a tactile sensory organ, and can be ...

, and the tendon of

depressor labii inferioris muscle The depressor labii inferioris (or quadratus labii inferioris) is a facial muscle. It helps to lower the bottom lip. Structure The depressor labii inferioris muscle arises from the lateral surface of the mandible. This is below the mental fora ...

. It is at the end of the

, which begins at the

mandibular foramen The mandibular foramen is an opening on the internal surface of the ramus of the mandible. It allows for divisions of the mandibular nerve and blood vessels to pass through. Structure The mandibular foramen is an opening on the internal surfa ...

on the posterior surface of the mandible. It transmits the terminal branches of the

(the

mental nerve The mental nerve is a sensory nerve of the face. It is a branch of the posterior trunk of the inferior alveolar nerve, itself a branch of the mandibular nerve (CN V3), itself a branch of the trigeminal nerve (CN V). It provides sensation to the f ...

), the

mental artery The inferior alveolar artery (inferior dental artery) is an artery of the face. It is a branch of the first portion of the maxillary artery. Structure It descends with the inferior alveolar nerve to the mandibular foramen on the medial surface of ...

, and the mental vein.

Variation

The mental foramen descends slightly in toothless individuals. The mental foramen is in line with the longitudinal axis of the 2nd

premolar The premolars, also called premolar teeth, or bicuspids, are transitional teeth located between the canine and molar teeth. In humans, there are two premolars per quadrant in the permanent set of teeth, making eight premolars total in the mouth ...

in 63% of people. It generally lies at the level of the vestibular fornix and about a finger's breadth above the inferior border of the mandible. In the general population, 17% of mandibles have an additional mental foramen or foramina on at least one side, while 4% of the mandibles show multiple mental foramina on both sides. Most are unequal in size, often with a single large foramen while any others are smaller. An incisive mental foramen is observed in 1% of the side of the mandible.

Clinical significance

The

may be anaesthetized as it leaves the mental foramen. This causes loss of sensation to the lower lip and chin on the same side.

Additional images

File:Gray188.png, Side view of the skull. File:Foramen mentale.PNG, The skull from the front. File:Gray778.png, Distribution of the maxillary and mandibular nerves, and the submaxillary ganglion. File:Gray781.png, Mandibular division of the trifacial nerve. File:Gray1003.png, The permanent teeth, viewed from the right.

References

External links