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Mandible: want to learn more about it?

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Mandible

The mandible is the only bone in the entire skull that doesn’t articulate with its adjacent skull bones via sutures. When the skull is observed purely as a bony structure, there is nothing anatomically holding the rest of the skull and the mandible together.

This bone is also known as the lower jaw and it articulates dentally with the upper jaw or the maxilla in the viscerocranium via the teeth when the mouth is closed. It also articulates to the neurocranium via the temporal bone, forming the temporomandibular joint (TMJ).

Key facts about the mandible
Body

Borders: 
- superior (alveolar) - contains 16 cavities for the lower teeth
- inferior - free; medially is the place of attachment for the digastric muscle
Surfaces:
- inner - genial tubercles, digastric fossa, mylohyoid line
- outer - mandibular symphysis, mental foramen, external oblique line

Ramus Condylar process - articulates with temporal bone -> temporomandibular joint
Coroinoid process - attachment for temporalis muscle
Outer surface - attachment for masseter muscle
Inner surface - mandibular foramen
Foramina Mandibular foramen - inner surface of the ramus; passage for the inferior alveolar nerve and artery to the mandibular canal which exits through the mental foramen
Mental foramen - on the outer surface of the body; allows the inferior mandibular nerve and artery to exit the mandibular canal, when they become mental nerve and artery
Clinical relations Alveolar bone resorption, condylar fractures, tooth aplasia, osteoradionecrosis, osteomyelitis, cysts

This article will discuss the anatomy of the mandible.

Anatomy

The mandible is a singular bone that has a distinctive horse-shoe shape and is symmetrical on both sides. It is the moving part of the jaws when the body is engaged in the feeding process and for that reason all the muscles of mastication including the medial and lateral pterygoid muscles, the temporal muscle and the masseter muscle attach to it.

The mandible is only one of the skull bones. How well do you know the others? Test yourself with our skull bones quizzes and diagrams!

The lower jaw consists of no less than five individual parts that intramembranously ossify together, especially around Meckel’s cartilage.

Ramus

The ramus is the second largest part of the mandible after the body and it extends cranially from the angle of the mandible, away from the body at an angle of 110 degrees. Various structures attach themselves to both the lateral and medial walls of the ramus, including the masseter muscle laterally and the medial pterygoid muscle, and the sphenomandibular ligament to the medial side.

At the most superior point of the ramus, it divides into two processes, which are separated by a mandibular notch. Anteriorly, sits the coronoid process and posteriorly, the condylar process, which articulates with the temporal bone.

Coronoid process

The coronoid process, as previously mentioned, is the foremost structure at the head of the ramus, attaches to the temporalis muscle, which is utilized during mastication. Although it is not directly part of the temporomandibular joint, it still aids the various functions of the jaws, such as opening and closing, due to its proximity to the TMJ and it involvement with its adjacent structures.

Condylar process

The condylar process is the bony extrusion behind the coronoid process, which forms the lower bony component of the temporomandibular joint, along with the temporal bone. It is formed differently to the coronoid process, because it has a much more slender stalk with a greater protuberance to top it off. This design creates a neck for the condyle and allows the lateral pterygoid muscle to attach to the pterygoid fovea upon it.

Body

The body of the mandible is a large and almost rectangular element that sits parallel or perpendicular to the floor, depending on when the person is standing upright or lying down flat respectively. This part of the bone contains the most anatomical landmarks of the mandible, which are discussed below, as they are part of the mandible’s osseous development.

Alveolar process

The last part of the mandible is the alveolar process. This is arguably the most important part of the bone in its entirety, since it holds the teeth via a joint mechanism known as gomphosis. The teeth are responsible for biting, chewing, cutting and grinding, as well as speech and pronunciation and facial tissue support.

This part of the mandible extends superiorly from the body and consists of two bony plates including a thick buccal part and a thin lingual part. Symmetrically, each side of the mandible contains five primary teeth and seven to eight permanent teeth, depending on whether the wisdom teeth or third molars form during embryonic development.

If you want to learn about the mandible using videos, illustrations and quizzes, click on the following study unit:

Surface structures

The medial side of the ramus contains the mandibular foramen, which encapsulates the inferior alveolar nerve and its branches. The lateral body of the mandible contains the mental foramen anteriorly, which houses the mental nerve and its corresponding vessels.

Also on the lateral side, the external oblique line can be seen. On the medial side of the mandible there are seven major structures that are worth noting, including the superior and inferior genial tubercles and the digastric fossa, which are found in the midline, as well as the mylohyoid line, whose posterior border allows for the attachment of the pterygomandibular raphe.

The mylohyoid line divides the submandibular and the sublingual fossae.

Mandible: want to learn more about it?

Our engaging videos, interactive quizzes, in-depth articles and HD atlas are here to get you top results faster.

What do you prefer to learn with?

“I would honestly say that Kenhub cut my study time in half.” – Read more. Kim Bengochea Kim Bengochea, Regis University, Denver

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