Mandible Bone (Lower Jaw): Anatomy, Function, and Common Problems

Mandible Bone (Lower Jaw): Anatomy and Function

The mandible is your lower jawbone. It supports your bottom teeth and gives shape to your chin and lower face.^1,2 It moves at the temporomandibular joints (TMJs), just in front of your ears, so you can chew, speak, and yawn.¹

Mandible Bone Quick Facts

• Location: Below the maxilla, which forms the upper jaw.
• Main parts: A curved body and two upright branches called rami. The anatomy table below explains the smaller landmarks.
• Other names: Lower jaw, lower jawbone, or mandibular bone.

Mandible Anatomy and Structure

The mandible has a horseshoe-shaped body with a ramus rising from each end. At the top of each ramus, the condylar process helps form the TMJ.¹

The curved body forms the lower jaw, while the rami rise toward the jaw joints. Match the labeled projections and openings to the table below.

Enlarge the mandible diagram

Scroll horizontally to see the full-size diagram. Keyboard users can focus the image region and use the arrow keys.

Parts of the Mandible at a Glance

The table includes landmarks shown in the diagram, plus the angle, notch, condylar neck, and internal canal.¹

Body

The body forms your chin and jawline. The mandibular symphysis marks the midline where the two halves of the developing mandible joined.¹

Its upper, tooth-bearing border is called the alveolar part. The lower border forms the base of the jaw.¹

Ramus

Each ramus rises from the body at the mandibular angle, also called the gonial angle. Two projections extend from its upper end:¹

• Condylar process: The rear projection has a rounded head and a narrower neck. The head articulates with the temporal bone through the TMJ’s joint disc.
• Coronoid process: The front projection provides an attachment for the temporalis muscle, which helps close the jaw.

The mandibular notch lies between these projections. The condylar neck also provides an attachment for part of the lateral pterygoid muscle.¹

Alveolar Process

The alveolar process, or alveolar part, contains the sockets that support your lower teeth.¹² The periodontal ligament connects each tooth root to the surrounding socket bone.¹

Mandibular Foramen and Mental Foramen

The mandibular foramen sits on the inner surface of the ramus. The inferior alveolar nerve and blood vessels enter here and travel through the mandibular canal.¹

The mental foramen is on the outer surface of the body, usually in the premolar region. It often lies near the second premolar, but its position varies.¹¹ The mental nerve exits here and supplies sensation to the lower lip and chin.¹

What Are the Primary Functions of the Mandible?

The mandible supports the lower teeth and moves them against the upper teeth to bite and chew. Its movement also helps with speech and opening your mouth.¹

The TMJs connect the mandible to the skull, but they are joints, not separate jawbones. Their coordinated rotation and sliding let the jaw open, close, and move forward or sideways.¹

Mandible vs. Maxilla

The mandible forms the lower jaw, while the maxilla forms the upper jaw. Their different positions and movement help explain how your bite works.^1,2

Other Jaw Structures

Nerves, blood vessels, and muscles work with the mandible to support sensation, nourishment, and movement.

Blood and Lymph Vessels

Branches of the inferior alveolar artery supply the lower teeth. Other small vessels supply the jawbone and its outer covering.¹

Lymphatic vessels carry fluid toward nearby lymph nodes, including those beneath the jaw.¹

Nerves

The inferior alveolar nerve branches from the mandibular division of the trigeminal nerve. It passes through the mandibular canal and sends branches to the lower teeth.¹

Near the mental foramen, it divides into two terminal branches:¹

• Mental nerve: Leaves the bone through the mental foramen and supplies sensation to the lower lip and chin.
• Incisive nerve: Continues forward within the bone to supply the front lower teeth.

Muscles

Four main chewing muscles move the mandible:¹³

• Masseter: Raises the jaw to close the mouth.
• Temporalis: Raises the jaw and helps pull it backward.
• Medial pterygoid: Helps raise the jaw and move it from side to side.
• Lateral pterygoid: Helps move the jaw forward, open it, and produce side-to-side movement.

Other muscles assist chewing and swallowing. The mylohyoid supports the floor of the mouth, while the buccinator helps keep food between the teeth.^1,13

What Problems Can Affect the Lower Jaw?

Problems can involve the jawbone, its joints, or the surrounding muscles. Similar symptoms can have different causes, so persistent pain or a changed bite needs professional evaluation.

Jaw Fractures

A broken mandible can cause pain, swelling, difficulty chewing, and a bite that suddenly feels different. Falls, vehicle crashes, sports injuries, and assaults are common causes.³

Treatment depends on the location and severity of the break. An oral and maxillofacial surgeon may stabilize the jaw or repair the fracture with plates and screws.³ A suspected fracture needs urgent assessment.

Jaw Misalignment

Jaw misalignment can affect how your upper and lower teeth meet. Depending on its severity, it may make chewing or speaking difficult.⁴

Tooth alignment and jawbone alignment are different problems. Braces or clear aligners move teeth, but they do not generally correct a major skeletal jaw discrepancy.⁵

Some people need corrective jaw surgery combined with orthodontic treatment. An orthodontist and oral surgeon can determine whether the problem involves the teeth, the jaws, or both.⁵

Dislocations

A dislocated jaw often leaves the mouth stuck open. It can happen after a wide yawn, a dental procedure, or an injury.⁶

Get prompt medical care if you cannot close your mouth. A clinician may need to guide the joint back into place; do not try to force it yourself.⁶

Temporomandibular Joint Disorders (TMD)

TMD refers to disorders affecting the jaw joints and chewing muscles. Symptoms can include jaw pain, stiffness, limited opening, or painful jaw popping or clicking.⁷

Painless clicking is common and usually does not need treatment. Pain or jaw locking should be evaluated.⁷

Conservative care may include soft foods, heat or cold, and clinician-guided jaw exercises. Evidence that splints or night guards improve TMD pain is limited.⁷ If a clinician recommends an appliance, it should not permanently change your bite. Avoid irreversible bite changes or surgery as an initial approach.⁷

Sleep Apnea

Sleep apnea is a breathing disorder during sleep, not a disease of the mandible itself. Signs include loud snoring, gasping, witnessed breathing pauses, and daytime sleepiness.⁸

Sleep apnea and TMD can occur together, but their association does not establish that one causes the other.⁹ Ask your doctor about a sleep evaluation if you have these breathing symptoms.

Jawbone Infection (Osteomyelitis)

Osteomyelitis is an infection of the bone. In the jaw, it can develop after a dental abscess, an oral procedure, or a fracture.¹⁰

Symptoms may include worsening jaw pain, swelling, fever, or drainage. Treatment can involve antibiotics and, in some cases, surgery to drain infection or remove damaged bone.¹⁰

When to See a Dentist or Doctor

The urgency depends on your symptoms. Breathing problems or rapidly spreading swelling need a different response from persistent clicking or soreness.

Get Emergency Help Now

Call 911 or go to an emergency department if swelling in your mouth or neck makes breathing, speaking, or swallowing difficult.¹⁴ Severe or rapidly spreading swelling also needs emergency assessment, especially with eye swelling or vision changes.¹⁴

Seek Urgent Assessment

• After an injury: A changed bite, visible jaw deformity, or suspected fracture needs urgent evaluation.³
• If your mouth is stuck open: A possible dislocation needs prompt medical care.⁶
• For possible infection: Jaw pain with fever, swelling, pus, or drainage needs prompt dental or medical assessment.^10,14

Arrange a Nonemergency Appointment

For ongoing jaw pain, painful clicking, or limited opening without the warning signs above, start with your dentist.⁷ Loud snoring, nighttime gasping, or witnessed breathing pauses warrant a medical appointment for possible sleep apnea.⁸