Mandible is the lower jaw bone, lying beneath the upper jaw and forming the lower boundary of the face. It supports the lower teeth and articulates, or forms a joint, with the temporal bone on each side of the skull, allowing movements used in chewing and speech.
Where is the mandible located?
The mandible belongs to the viscerocranium, the facial skeleton. Within the skeletal system, the body's framework of bones, it forms the movable lower jaw beneath the maxilla, the bone of the upper jaw. Its front forms the bony chin, while its sides extend backwards towards the joints near the ears.
The tongue and floor of the mouth lie within the curve of the mandible. The cheek lies outside it, and several chewing muscles attach to its sides. At the back, its upper projections approach the temporal bones, which form part of the sides and base of the skull.
What are the main parts of the mandible?
The mandible has a curved, roughly horseshoe-shaped body and an ascending ramus on each side. A ramus is an upright branch of bone. The angle of the mandible is the corner where the lower border of the body meets the back border of a ramus.
Each ramus ends above in two processes, meaning bony projections. The coronoid process lies in front and the condylar process behind; the mandibular notch is the curved depression between them.
| Part | Location | Main anatomical role |
|---|---|---|
| Body | Curved lower portion | Supports the lower teeth and forms the chin |
| Ramus | Ascending portion on each side | Provides muscle attachments and carries the upper processes |
| Angle | Junction of body and ramus | Provides attachment for chewing muscles |
| Coronoid process | Front upper projection of the ramus | Receives the temporalis muscle attachment |
| Condylar process | Back upper projection of the ramus | Forms the mandibular part of the jaw joint |
What landmarks are on the outer surface?
The mandibular symphysis is the midline region where the two halves of the developing mandible unite. In the adult it is fused, rather than a movable joint. Below it, the mental protuberance is the prominence that forms the bony chin; here, mental means relating to the chin.
The mental foramen is an opening on each outer side of the body, usually below the premolar teeth, which lie between the canine and molar teeth. It transmits the mental nerve and accompanying blood vessels to the chin and lower lip.
The alveolar part is the tooth-bearing upper region of the body. It contains the tooth sockets, also called dental alveoli. The oblique line is a ridge running backwards and upwards on the outer surface towards the front border of the ramus.
What landmarks are on the inner surface?
The mandibular foramen is an opening on the inner surface of each ramus. It leads into the mandibular canal, a passage within the bone carrying the inferior alveolar nerve and blood vessels. The nerve supplies sensation to the lower teeth, and its mental branch leaves through the mental foramen.
The lingula is a small tongue-shaped projection beside the mandibular foramen. It provides attachment for the sphenomandibular ligament, a band of connective tissue extending from the sphenoid bone at the skull base to the mandible.
Other inner landmarks include:
- Mylohyoid line: a ridge that gives attachment to the mylohyoid muscle, which supports the floor of the mouth.
- Sublingual fossa: a shallow depression above the front part of the mylohyoid line, related to the sublingual salivary gland.
- Submandibular fossa: a depression below the back part of the line, related to the submandibular salivary gland.
- Mental spines: small projections near the inner midline for attachment of muscles extending towards the tongue and hyoid bone, a separate bone in the neck.
How does the mandible form the jaw joint?
The condylar process consists of a head supported by a narrowed neck. Its head meets the mandibular fossa and articular tubercle of the temporal bone. These are, respectively, a hollow and an adjacent raised surface that participate in the temporomandibular joint.
An articular disc, a pad of fibrous connective tissue, separates the joint into upper and lower compartments. Rotation occurs mainly below the disc, while sliding occurs mainly above it. These movements work together during opening and closing.
Within the articular system, meaning the joints and their supporting structures, the paired temporomandibular joints allow coordinated jaw movement. The mandible can also move forwards, backwards and from side to side.
Which muscles attach to the mandible?
The main chewing muscles of the muscular system, the muscles that produce movement, attach to different mandibular landmarks:
- Masseter: attaches to the outer surface of the ramus and angle and raises the jaw.
- Temporalis: attaches to the coronoid process and anterior border of the ramus; it raises the jaw, and its posterior fibres draw it backwards.
- Medial pterygoid: attaches to the inner surface near the angle and helps raise the jaw.
- Lateral pterygoid: attaches to the front of the condylar neck and the joint capsule, with variable attachment to the joint disc; it helps move the jaw forwards and contributes to opening.
Muscles attached to the inner body also connect the mandible with the tongue, floor of the mouth and hyoid bone.
What does the mandible do?
The mandible supports the lower teeth and moves them against the upper teeth. This breaks food into smaller pieces during chewing, an initial mechanical step in the work of the digestive system, which processes food and absorbs nutrients.
It also provides a firm base for tongue and floor-of-mouth muscles. Its movements help alter the oral space during speech.
How can you find the mandible in the 3D model?
In the 3D model next to this article, select the mandible and isolate it, then rotate and zoom. You can hide or fade selected parts, switch layers, or cut a section along the sagittal, coronal or transverse plane. You can also pull parts apart, then rotate and zoom again.