Mandible Anatomy and Ossification Quiz

The mandible is the strongest and largest bone in the face.
It forms the lower jaw and contains the lower teeth.
The mandible articulates on either side with the temporal bone, forming the temporomandibular joint (TMJ).

Ossification of the mandible begins around 6 weeks of intrauterine life.
Ossification occurs via intramembranous ossification on the outer surface of Meckel's cartilage.
Meckel's cartilage is located inferior to the incisor teeth and forms the mandible.
Accessory pieces of cartilage are found in the coronoid process, condyloid process, and mental symphysis.
These cartilage pieces are eventually absorbed.
At birth, the mandible consists of two symmetrical halves, united by fibrous tissue at the mental symphysis.
The union of these two halves is complete by the age of one year.

The mandible consists of a horizontal body (anteriorly) and two vertical rami (posteriorly).
The body and rami meet on each side at the angle of the mandible.

The lower border is known as the base.
The oblique line runs along the lower border and is continuous with the anterior border.
Several muscles attach to the oblique line.

The mylohyoid line divides the internal surface into upper and lower parts.
The mylohyoid muscle attaches to the mylohyoid line.
The superior constrictor muscle of the pharynx attaches to the internal surface.
The digastric fossa is located on the internal surface.
The mental spine is a small projection on the internal surface.
The genial tubercles are small projections on the internal surface, with the upper two providing attachment for the genioglossus muscle and the lower two providing attachment for the geniohyoid muscle.
The sublingual fossa is located on the internal surface.
The submandibular fossa is located on the internal surface.

The external surface of the ramus is flat and provides attachment to the masseter muscle.
The facial artery is located anterior to the masseter muscle attachment.
The parotid gland lies above and behind the ramus.

The internal surface of the ramus is rough.
The mandibular foramen leads to the mandibular canal, which houses the inferior alveolar nerve.
The lingula is a small projection located near the mandibular foramen and serves as the attachment point for the sphenomandibular ligament.
The internal surface also provides attachment for the temporalis, lateral pterygoid, and medial pterygoid muscles.

The posterior part of the superior border forms the condyloid process, which ends in the head.
The head of the condyloid process articulates with the mandibular fossa of the temporal bone.
The neck lies below the head and provides attachment for the lateral pterygoid muscle.
The capsule of the TMJ encapsulates the joint.
The lateral ligament of the TMJ is located on the lateral side of the neck.
The anterior part of the superior border forms the coronoid process, which is flat and triangular.
The mandibular notch is located between the coronoid process and condyloid process and contains the masseteric vessels and nerves.

The inferior border is continuous with the inferior border of the body.
The angle of the mandible is formed at the junction of the inferior border of the body and the ramus.
The stylomandibular ligament attaches to the angle of the mandible.

This group includes 3 pairs of muscles that elevate the mandible to close the mouth.

This group includes 1 pair of muscle that depresses the mandible (opening the mouth), translates the jaw from side to side, and protrudes the mandible forward.

The temporalis is a large, fan-shaped muscle.
It is a powerful elevator of the mandible.
Origin: Floor of the temporal fossa and deep surface of the temporal fascia.
Insertion: Coronoid process and anterior border of the ramus up to the last molar.
Innervation: Deep temporal branches of the anterior trunk of the mandibular nerve.
Action: Elevates the mandible (closing the jaws), retracts the mandible after protrusion (posterior fibers).

The masseter is a powerful masticatory muscle.
It is quadrangular in shape.
It has two parts: superficial and deep.
Origin (Superficial): Maxillary process of the zygomatic bone and anterior two-thirds of the zygomatic arch.
Insertion (Superficial): Angle of the mandible and lateral surface of the ramus.
Origin (Deep): Medial surface of the zygomatic arch and posterior part of the inferior margin.
Insertion (Deep): Central and upper part of the lateral surface of the ramus and the coronoid process.
Innervation: Masseteric nerve (branch of the mandibular nerve).
Action: Elevates the mandible (closing the jaw), protrudes the mandible.