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M01.02.015 Mandible
The mandible, located inferiorly in the facial skeleton, is the largest and strongest bone of the face. This guide covers its anatomical structure, muscular attachments, articulations, and clinical significance.
Overview
The mandible, or lower jawbone, forms the framework for the lower teeth and articulates with the temporal bone at the temporomandibular joint. It plays a crucial role in mastication, facial structure, and speech.
Anatomical Structure
The mandible comprises a horizontal body and two vertical rami, which meet at the mandibular angle.
Body
The body of the mandible is U-shaped, curving horizontally. It has two borders:
- Alveolar Border (Superior): Contains 16 sockets for the lower teeth.
- Base (Inferior): Provides attachment for the digastric muscle medially.
Notable Features:
- Mandibular Symphysis: A ridge marking the fusion point of the two halves of the mandible during development.
- Mental Protuberance: Forms the chin and is located at the midline.
- Mental Foramen: Positioned below the second premolar tooth, allowing passage for neurovascular structures.
Rami
The rami are two perpendicular projections on either side of the mandible. Each ramus includes:
- Head: Articulates with the temporal bone to form the temporomandibular joint.
- Neck: Attachment point for the lateral pterygoid muscle.
- Coronoid Process: Site of attachment for the temporalis muscle.
On the internal surface of each ramus is the mandibular foramen, which serves as a conduit for neurovascular structures.
Foramina
The mandible contains two key foramina that facilitate neurovascular passage:
| Foramen | Location | The internal surface of the ramus |
|---|---|---|
| Mandibular Foramen | The internal surface of the ramus | Passage for inferior alveolar nerve and artery |
| Mental Foramen | The external surface of the mandibular body (below the second premolar) | Allows the inferior alveolar nerve to exit as the mental nerve, innervating the chin and lower lip |
Muscular Attachments
The mandible serves as the attachment for several muscles, including key muscles of mastication.
| Muscle | The external surface of the mandibular body |
|---|---|
| Mentalis, Buccinator, Platysma | External surface of the mandibular body |
| Genioglossus, Geniohyoid, Mylohyoid, Digastric | Internal surface of the mandibular body |
| Masseter, Temporalis, Medial & Lateral Pterygoid | Rami of the mandible |
- Coronoid Process: Attachment for the temporalis muscle.
- Neck of the Mandible: Attachment for the lateral pterygoid muscle.
Articulations
The mandible articulates with the temporal bone to form the temporomandibular joint (TMJ), allowing jaw movements essential for chewing and speaking.
Clinical Relevance
Fractures of the Mandible
Mandibular fractures often occur with a second fracture on the contralateral side. Key types of fractures include:
- Coronoid Process: Uncommon and typically singular.
- Neck of the Mandible: Often transverse and may involve TMJ dislocation.
- Angle of the Mandible: Typically oblique and may involve the third molar.
- Body of the Mandible: Often passes through the canine tooth.
| Type of Fracture | Characteristics |
|---|---|
| Coronoid Process | Rare and isolated |
| Neck of the Mandible | Transverse with TMJ dislocation |
| Angle of the Mandible | Oblique may involve the third molar |
| Body of the Mandible | Often through the canine tooth |
Points to Remember
- The mandible is essential for mastication, speech, and structural support.
- Two key foramina, the mandibular and mental, allow for neurovascular passage.
- The mandible is subject to fractures, which are frequently accompanied by a contralateral fracture.
Bibliography
- TeachMeSeries Ltd. (2024). Anatomy of the Mandible.
- Coronation Dental Specialty Group. Mandibular Fractures