Facial Bones

The facial bones, also known as the viscerocranium, form the framework of the face and support many essential functions such as breathing, eating, and communication. They contribute to the nasal cavity, orbits, and oral cavity, while also giving shape and definition to the face. The facial skeleton is composed of 14 bones, many of which are paired, and they articulate with each other and with cranial bones to create the facial anatomy.

Structure

There are 14 facial bones in total, out of which 12 are paired and 2 are unpaired:

• Maxilla (2)
• Zygomatic bones (2)
• Nasal bones (2)
• Lacrimal bones (2)
• Palatine bones (2)
• Inferior nasal conchae (2)
• Vomer (1)
• Mandible (1)

These bones are connected by sutures, except for the mandible, which forms a movable joint with the temporal bones (the temporomandibular joints).

Location

The facial bones are located in the lower half of the skull, anterior and inferior to the cranial bones. They surround the entrances to the digestive and respiratory tracts and form the bony cavities of the orbits, nasal cavity, and oral cavity.

Functions

• Support: Provide structural framework for the face, orbits, and upper airway.
• Protection: Encase and protect vital sensory organs like the eyes, nose, and tongue.
• Attachment: Serve as anchor points for muscles of facial expression, mastication, and speech.
• Airflow regulation: Help form the nasal cavity and sinuses, which condition the inhaled air.
• Chewing and speech: Maxilla and mandible house the teeth and contribute to occlusion, chewing, and articulation of speech.

Individual Facial Bones

1. Maxilla (Paired)

The maxillae are the largest bones of the face, forming the upper jaw. Each maxilla articulates with the nasal, zygomatic, frontal, and palatine bones. They contribute to the floor of the orbit, walls of the nasal cavity, and anterior hard palate.

• Key features: Infraorbital foramen, alveolar processes (tooth sockets), palatine processes, maxillary sinuses.
• Function: Support the upper teeth and separate the nasal and oral cavities.

2. Zygomatic Bones (Paired)

Also known as the cheekbones, the zygomatic bones form the prominence of the cheeks and part of the lateral wall and floor of each orbit. They articulate with the maxilla, temporal, sphenoid, and frontal bones.

• Key features: Zygomatic arch (with temporal bone), frontal process, temporal process.
• Function: Contribute to facial aesthetics and protect the orbits.

3. Nasal Bones (Paired)

These small rectangular bones form the bridge of the nose. They articulate with the frontal bone superiorly, maxilla laterally, and each other medially.

• Function: Support the cartilage of the nose and form the upper part of the nasal cavity.

4. Lacrimal Bones (Paired)

The lacrimal bones are the smallest bones in the face. Located in the medial wall of each orbit, they contain the lacrimal fossa for the lacrimal sac, which is part of the tear drainage system.

• Function: Facilitate tear drainage from the eye into the nasal cavity.

5. Palatine Bones (Paired)

These L-shaped bones are located at the back of the nasal cavity. Each has a horizontal plate forming the posterior part of the hard palate and a vertical plate forming part of the lateral nasal wall and a small part of the orbit.

• Function: Contribute to the hard palate, nasal cavity, and orbital floor.

6. Inferior Nasal Conchae (Paired)

Curved, scroll-like bones projecting from the lateral walls of the nasal cavity. They are separate bones (unlike the superior and middle nasal conchae, which are part of the ethmoid bone).

• Function: Increase the surface area of the nasal cavity to help warm, humidify, and filter inhaled air.

7. Vomer (Unpaired)

The vomer is a thin, plow-shaped bone that forms the inferior part of the nasal septum. It articulates with the ethmoid, maxillae, and palatine bones.

• Function: Helps divide the nasal cavity into left and right halves.

8. Mandible (Unpaired)

The mandible, or lower jawbone, is the largest and strongest facial bone. It holds the lower teeth and forms the only movable joint in the skull — the temporomandibular joint (TMJ) — where it articulates with the temporal bone.

• Key features: Body, ramus, mandibular condyle, coronoid process, mental foramen, mandibular foramen.
• Function: Supports lower teeth, enables chewing, speech, and facial expression.

Development and Ossification

The facial bones primarily develop from neural crest-derived mesenchyme. Most undergo intramembranous ossification, meaning they form directly from mesenchymal tissue without a cartilage model. Exceptions include parts of the mandible and hyoid-related structures, which involve endochondral ossification.

• Mandible ossifies from Meckel’s cartilage (endochondral + intramembranous).
• Maxilla and other facial bones form via intramembranous ossification.

Clinical Relevance

1. Facial Fractures

Facial bones are prone to trauma. Common types include:

• Nasal bone fracture: Most common facial fracture.
• Zygomatic fracture: Can cause flattening of the cheek and orbital complications.
• Maxillary fractures: Classified by Le Fort types I–III.
• Mandibular fracture: May result in malocclusion, nerve injury, or airway obstruction.

2. Temporomandibular Joint Disorders (TMD)

Dysfunction in the TMJ (mandibular articulation) can cause pain, jaw locking, clicking, and difficulty chewing.

3. Congenital Anomalies

• Cleft palate: Failure of fusion between the palatine processes of the maxilla and palatine bones.
• Craniofacial syndromes: Such as Treacher Collins or Crouzon syndrome involve malformations of the facial skeleton.

4. Sinus Infections

Maxillae and other facial bones contain sinuses that can become inflamed or infected, leading to sinusitis.

5. Dental and Orthodontic Issues

Malalignment of the maxilla or mandible can affect occlusion, speech, and facial aesthetics. These conditions may require orthodontic or surgical correction.

Radiological Identification

Facial bones are visualized using X-rays, CT scans, and MRI when evaluating trauma, tumors, or congenital defects. Important landmarks include the infraorbital foramen, zygomatic arch, nasal septum, and mental foramen.