The mandibular foramen, also known as the mental foramen, is a small opening located on the posterior aspect of the mandible, the lower jaw bone. It is an important structure in the anatomy of the head and neck, with various functions and clinical significance.
Structure
The mandible, or lower jaw bone, is a horseshoe-shaped bone that forms the lower border of the face. It consists of a body, which is the main part of the bone, and two rami, which are the projecting parts of the bone that form the joints with the temporal bones of the skull. The mandibular foramen is located on the posterior aspect of the body of the mandible, on either side of the midline.
The mandibular foramen is an oval-shaped opening that is surrounded by a bony margin. The size of the mandibular foramen varies among individuals, with an average size of about 8mm in width and 12mm in length. The mandibular foramen is not a single, continuous opening but rather consists of two separate openings, one on each side of the midline, separated by a thin bony septum.
The mandibular foramen is bordered by several important structures. Anteriorly, it is bordered by the posterior border of the body of the mandible. Posteriorly, it is bordered by the medial surface of the ramus of the mandible. Medially, it is bordered by the mandibular canal, which is a long, narrow tunnel that runs through the body of the mandible. Laterally, it is bordered by the mandibular angle, which is the angle formed between the body and ramus of the mandible.
Location
The mandibular foramen is located on the posterior aspect of the body of the mandible, on either side of the midline. It is located at the level of the second premolar tooth, which is the tooth just behind the canine (eyetooth) on the mandible. The mandibular foramen is located approximately 3-4cm below the mandibular symphysis, which is the midline joint between the two halves of the mandible.
It can be easily palpated, or felt, through the skin by applying gentle pressure to the area just below the mandibular symphysis. It is also visible on radiographic images, such as a panoramic dental x-ray or a CT scan.
Function
The mandibular foramen serves several important functions in the anatomy of the head and neck. One of the main functions of the mandibular foramen is to allow the passage of the mental nerve and artery, which are branches of the trigeminal nerve and external carotid artery, respectively. The mental nerve and artery provide innervation and blood supply to the lower lip, chin, and skin of the lower face.
In addition to the mental nerve and artery, the mandibular foramen also allows the passage of the mentalis muscle, which is a small muscle that helps to elevate and protrude the lower lip. The mentalis muscle is innervated by the facial nerve, which also passes through the mandibular foramen.
It is also an important landmark in dentistry and oral surgery. It is used as a reference point for the placement of dental implants and other surgical procedures in the mandible. In some cases, the mandibular foramen may also be used as an access point for the placement of a mandibular nerve block, which is a type of local anesthesia used to numb the lower lip, chin, and skin of the lower face.
