Facial Skeleton

The facial skeleton, also known as the viscerocranium, forms the framework of the face. It supports the facial muscles, houses sensory organs, and contributes to important functions such as breathing, eating, and communication. Unlike the neurocranium, which encases the brain, the facial skeleton defines the shape and appearance of the face.

Structure

The facial skeleton is composed of 14 individual bones. Most of these bones are paired, meaning they exist on both the left and right sides of the face, except for two unpaired bones—the vomer and mandible. These bones are joined together by sutures, except for the mandible, which articulates with the temporal bones to form the temporomandibular joints (TMJ).

The 14 Facial Bones Include:

• Maxilla (2) – form the upper jaw and most of the hard palate.

• Zygomatic bones (2) – form the cheekbones and part of the orbit.

• Nasal bones (2) – form the bridge of the nose.

• Lacrimal bones (2) – small bones forming part of the medial wall of the orbit.

• Palatine bones (2) – form the posterior part of the hard palate and parts of the nasal cavity and orbit.

• Inferior nasal conchae (2) – curved bones within the nasal cavity that help filter and humidify inhaled air.

• Vomer (1) – forms the lower part of the nasal septum.

• Mandible (1) – the lower jawbone and the only movable bone of the facial skeleton.

Location

The facial skeleton is located in the anterior and inferior part of the skull, below the cranial cavity. It extends from the superior margin of the orbit (just below the frontal bone) to the lower border of the mandible. It is bordered posteriorly by the temporal and sphenoid bones of the cranium and is oriented to support the upper airway, oral cavity, and sense organs.

Function

• Support: Provides structure and shape to the face and houses the upper and lower teeth.

• Protection: Encases the eyes, nasal cavity, and oral cavity, protecting vital sensory organs and passageways.

• Muscle Attachment: Serves as the anchoring point for muscles responsible for facial expression, chewing, speech, and eye movement.

• Passageways: Contains foramina and canals for nerves and blood vessels supplying the face and oral structures.

Anatomy of Individual Facial Bones

Maxilla

The maxillae are paired bones that form the central part of the face. Each maxilla contributes to the formation of the upper jaw, the floor of the orbit, the lateral walls of the nasal cavity, and the anterior part of the hard palate. The infraorbital foramen on each maxilla transmits the infraorbital nerve and vessels. The maxillary sinuses, located within each bone, are the largest of the paranasal sinuses.

Zygomatic Bones

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

Nasal Bones

These small paired bones form the upper part of the bridge of the nose. They articulate with each other at the midline and with the frontal bone superiorly and the maxillae laterally.

Lacrimal Bones

The smallest bones in the face, the lacrimal bones are located in the medial wall of each orbit. Each has a groove that forms the nasolacrimal canal, which drains tears from the eye into the nasal cavity.

Palatine Bones

Located at the back of the nasal cavity, the palatine bones are L-shaped and consist of horizontal and vertical plates. The horizontal plates form the posterior portion of the hard palate, while the vertical plates help form the lateral walls of the nasal cavity and a small part of the orbit.

Inferior Nasal Conchae

These thin, scroll-like bones project from the lateral walls of the nasal cavity. They increase the surface area of the nasal passageway, aiding in the warming, moistening, and filtering of inhaled air.

Vomer

The vomer is a plow-shaped bone that forms the inferior portion of the nasal septum. It sits vertically within the nasal cavity and articulates with the sphenoid, ethmoid, palatine, and maxillary bones.

Mandible

The mandible is the strongest and largest facial bone and the only one that moves. It supports the lower teeth and forms the lower jaw. It includes important landmarks such as the mental foramen, mandibular condyle, and coronoid process. The mandibular condyles articulate with the temporal bones to form the temporomandibular joints (TMJ), enabling jaw movement.

Associated Cavities and Sinuses

The facial skeleton surrounds several important cavities:

• Oral cavity: Bounded by the maxilla above and mandible below, it houses the teeth and tongue and is involved in chewing and speech.

• Nasal cavity: Enclosed by the nasal, maxilla, ethmoid, vomer, and palatine bones; allows airflow and olfaction.

• Orbits: House and protect the eyes; formed by contributions from both facial and cranial bones.

The maxillae contain the maxillary sinuses, which are air-filled spaces that lighten the facial bones and resonate the voice.

Development

The facial skeleton primarily develops from the first and second pharyngeal (branchial) arches during embryogenesis. Most bones of the facial skeleton ossify through intramembranous ossification, except for parts of the mandible and some regions of the hyoid bone that undergo endochondral ossification. Growth of the facial skeleton continues through childhood and adolescence, influenced by dental eruption, sinus expansion, and hormonal changes.

Clinical Relevance

• Facial fractures: Commonly involve the nasal bones, zygomatic arch, or mandible. Le Fort classification is used to describe maxillary fractures.

• Temporomandibular Joint Disorders (TMD): Dysfunction of the TMJ can cause pain, clicking, or limited jaw movement.

• Congenital anomalies: Conditions like cleft palate result from failure of fusion between palatine processes of the maxilla.

• Sinusitis: Inflammation or infection of the maxillary sinuses can cause facial pain and pressure.

• Dental alignment: The maxilla and mandible play a critical role in occlusion and orthodontic corrections.