The mental foramen is one of two

foramina In anatomy and osteology, a foramen (; : foramina, or foramens ; ) is an opening or enclosed gap within the dense connective tissue (bones and deep fasciae) of extant and extinct amniote animals, typically to allow passage of nerves, arter ...

(openings) located on the anterior surface of the

mandible In jawed vertebrates, the mandible (from the Latin ''mandibula'', 'for chewing'), lower jaw, or jawbone is a bone that makes up the lowerand typically more mobilecomponent of the mouth (the upper jaw being known as the maxilla). The jawbone i ...

. It is part of the mandibular canal. It transmits the terminal branches of the

inferior alveolar nerve The inferior alveolar nerve (IAN) (also the inferior dental nerve) is a sensory branch of the mandibular nerve (CN V3) (which is itself the third branch of the trigeminal nerve (CN V)). The nerve provides sensory innervation to the lower/mandibu ...

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 a horizontal pair of soft appendages attached to the jaws and are the most visible part of the mouth of many animals, including humans. Mammal lips are soft, movable and serve to facilitate the ingestion of food (e.g. sucklin ...

, 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 for ...

. It is at the end of the mandibular canal, which begins at the mandibular foramen on the posterior surface of the mandible. It transmits the terminal branches of the

(the mental nerve), the mental artery, 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 Tooth (human), teeth, or bicuspids, are transitional teeth located between the Canine tooth, canine and Molar (tooth), molar teeth. In humans, there are two premolars per dental terminology#Quadrant, quadrant in ...

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 mental nerve may be anaesthetized as it leaves the mental foramen. This causes loss of sensation to the lower lip and

chin The chin is the forward pointed part of the anterior mandible (List_of_human_anatomical_regions#Regions, mental region) below the lower lip. A fully developed human skull has a chin of between 0.7 cm and 1.1 cm. Evolution The presence of a we ...

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