Body of mandible

Corpus mandibulae

Definition

The mandible is made up of the body and two vertical rami. The body of mandible is divided into two halves, each with its outer and inner surfaces, as well as upper and lower borders.

On the outer surface, you’ll find notable features such as:

  • The mandibular symphysis or symphysis menti, which is where the right and left halves of the bone join, marked by a slight ridge.

  • The chin, scientifically known as the mental protuberance, is a triangular projection at the bottom middle part. The inferolateral corners of this area are called mental tubercles.

  • The mental foramen, located just below the interval between the premolar teeth. This allows for the passage of mental vessels and nerve.

  • The oblique line starts from the sharp front edge of the ramus and runs downwards and forwards towards the mental tubercle. It affords attachment to the Quadratus labii inferioris and Triangularis; the Platysma is attached below it.

  • The incisive fossa, a shallow depression found below the incisor teeth, which gives origin to the Mentalis and a small portion of the Orbicularis oris.

On the inner surface, the mandible features:

  • The mylohyoid line, a distinct ridge that angles downwards and forwards from below the third molar tooth to a central area beneath the genial tubercles or mental spines. It gives origin to the mylohyoid muscle, contributing to the floor of the oral cavity. The posterior most part of this line also gives attachment to the superior constrictor muscle of pharynx and pterygomandibular raphe.

  • Below this line, there's a slight depression called the submandibular fossa, which accommodates the submandibular gland.

  • Above it, the sublingual fossa provides a space for the sublingual gland.

  • The posterior surface of the symphysis menti is marked by four small bumps known as the superior and inferior mental spines, which give origin to the genioglossus and geniohyoid muscles, respectively.

  • The mylohyoid groove can be seen on the inner surface of mandible, which stretches from the ramus onto the body, below the posterior end of the mylohyoid line.

The upper border of the mandible, known as the alveolar border, contains sockets for the teeth.

Lastly, the mandible's lower edge, or base, features an oval depression near the center called the digastric fossa.

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Text written by Muhammad A. Javaid, MD, PhD © 2024 IMAIOS.

  • Drake, R.L., Vogl, A.W. and Mitchell, A.W.M. (2009). ‘Chapter 8: Head and Neck’ in Gray’s anatomy for Students. (2nd ed.) Philadelphia PA 19103-2899: Elsevier, pp. 814 & 922.

  • Breeland G, Aktar A, Patel BC. Anatomy, Head and Neck, Mandible. [Updated 2023 Apr 1]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK532292/


Comparative anatomy in animals

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