The human skull forms the protective shell for the brain and the structural foundation for the face. This complex bony structure is divided into the neurocranium and the viscerocranium. The neurocranium, or braincase, consists of eight bones that surround and safeguard the brain. The viscerocranium, commonly known as the facial skeleton, is composed of 14 bones that shape the face. These bones house the sensory organs, support the teeth, and provide openings for the respiratory and digestive systems.
The Two Unpaired Facial Bones
The facial skeleton includes two bones that exist as single, midline structures rather than mirrored pairs. The Mandible, or lower jawbone, is the largest and strongest bone of the face. It is the only movable bone of the entire skull, connecting to the temporal bones at the temporomandibular joints. This mobility allows for the motions of mastication (chewing) and articulated speech. It anchors the lower row of teeth and defines the lower contour of the face and chin.
The second unpaired bone is the Vomer, a thin, flat bone situated along the midline of the nasal cavity. It is located at the base of the nasal septum, forming the posterior and inferior division between the left and right nasal passages. The Vomer articulates with several other bones, including the maxillae and palatine bones, maintaining the structural integrity of the nasal architecture. This bone supports the separation necessary for airflow regulation.
The Six Paired Facial Bones
The remaining twelve facial bones are organized into six distinct pairs. The Maxillae fuse to form the upper jaw. These bones support the upper row of teeth and contribute to the framework of the mid-face. Each Maxilla helps form the floor of the orbit, the lateral walls of the nasal cavity, and the majority of the hard palate (the roof of the mouth).
The Zygomatics are located below and lateral to the eye sockets. They form the contours of the cheeks and contribute to the inferior and lateral boundaries of the orbits. The Zygomatics articulate with the frontal, temporal, and maxilla bones, creating the zygomatic arch that provides structural support for the face.
The Nasal Bones are positioned side-by-side at the superior part of the face, forming the bony bridge of the nose. Their lower margins connect with the cartilage that forms the remainder of the external nose. They articulate superiorly with the frontal bone and laterally with the maxillae, establishing the initial framework for the nasal passage.
The Lacrimal Bones are situated at the anterior-medial wall of the orbit. A groove in the bone houses the lacrimal sac, which drains tears from the eye into the nasal cavity. This feature makes the Lacrimal Bones a direct connection point between the eye and the nasal system.
Located at the posterior region of the nasal cavity, the Palatine Bones contribute to three different body cavities. They form the posterior quarter of the hard palate, completing the roof of the mouth behind the maxillae. They also contribute to the floor and lateral walls of the nasal cavity and a small part of the orbit.
The Inferior Nasal Conchae are thin, scroll-shaped bones that project into the nasal cavity. These bones, sometimes called turbinate bones, are distinct from the superior and middle conchae (which are part of the ethmoid bone). The Conchae increase the surface area within the nasal passages. This surface is covered in mucosa, which helps to warm, filter, and humidify the air inhaled before it reaches the lungs.
Essential Roles of the Facial Skeleton
The 14 facial bones perform a range of integrated functions. A primary role is providing a protective enclosure and support system for the sensory organs. The orbits, constructed by several facial bones, shield the delicate structures of vision. The nasal cavity, framed by the Nasal, Vomer, and Maxillary bones, protects the olfactory sensors responsible for smell.
The facial skeleton also serves as the structural base for sustenance and communication. The bones offer attachment sites for the muscles of facial expression, allowing humans to convey emotions through movement. The Maxilla and Mandible anchor the teeth, providing the necessary stability for chewing and the initial stage of digestion. The framework of the face forms the entrances to the respiratory and digestive tracts. Sinuses within some of these bones contribute to voice resonance and help reduce the skull’s weight.