Zygomatic bone anatomy: the cheekbone and the zygomatic arch

Also called

Cheekbone

What it is

The cheekbone.

Location

Lies at the side of the face, articulating with the frontal, maxilla, temporal and sphenoid bones.

Function

Forms the prominence of the cheek, part of the lateral wall and floor of the orbit, and the front part of the zygomatic arch.

Body system

Skeletal · paired (left and right)

FMA ID

FMA52893 (Foundational Model of Anatomy)

Key facts

• Its temporal process joins the zygomatic process of the temporal bone to form the zygomatic arch, from which masseter arises.
• It forms the lateral wall and part of the floor of the orbit; the zygomaticofacial and zygomaticotemporal nerves pass through small foramina in it.

Clinical relevance

A zygomaticomaxillary complex (tripod) fracture breaks its links to neighbouring bones and can involve the orbit.

There are two zygomatic bones, one on each side of the face. Each sits just below the outer edge of the eye socket and forms the prominence of the cheek. It is an irregular, nearly quadrangular bone with three surfaces, five borders and three processes. (Kenhub: Zygomatic bone.)

The zygomatic bone forms much of the lateral wall of the orbit and the lower lateral margin of the orbital opening. Behind, it forms the front part of the zygomatic arch. (OpenStax Anatomy and Physiology 2e, 7.2: The Skull.)

You can feel it on yourself: the hard ridge under the outer half of the lower eyelid and the curve of the cheek are both zygomatic bone. Following the cheek backward toward the ear, the bony bar you feel is the zygomatic arch.

The lateral (facial) surface is smooth and convex and is pierced by the zygomaticofacial foramen. The posteromedial (temporal) surface faces the temporal and infratemporal fossae and carries the zygomaticotemporal foramen. The orbital surface is smooth and concave, forms part of the floor and lateral wall of the orbit, and has the zygomatico-orbital foramen, the entrance to a small canal inside the bone. (Kenhub: Zygomatic bone.)

The bone has three processes. The frontal process (also called frontosphenoidal) runs up to meet the frontal bone and the greater wing of the sphenoid. The temporal process runs back to join the temporal bone. The maxillary process runs medially, joins the maxilla and helps form the orbital floor and rim. (Radiopaedia: Zygomatic bone.)

On the inner side of the frontal process, just inside the orbital rim, is a small bump called Whitnall's tubercle (the lateral orbital tubercle). The lateral palpebral ligament of the eyelids attaches here. Radiopaedia notes that the tubercle is absent in about 5 to 10% of skulls. (Radiopaedia: Zygomatic bone.)

The posteromedial border of the bone forms the lateral edge of the inferior orbital fissure, the gap in the orbital floor that leads back to the pterygopalatine and infratemporal fossae. (Radiopaedia: Inferior orbital fissure.)

The zygomatic bone joins four bones. Kenhub names three sutures on the face and orbit: the zygomaticomaxillary suture with the maxilla, the zygomaticofrontal suture with the frontal bone and the sphenozygomatic suture with the greater wing of the sphenoid. (Kenhub: Zygomatic bone.)

The fourth contact is behind: the temporal process joins the zygomatic process of the temporal bone to form the zygomatic arch. Radiopaedia lists all four: the frontosphenoidal process meets the frontal bone and sphenoid, the temporal process joins the temporal bone, and the maxillary border and process meet the maxilla. (Radiopaedia: Zygomatic bone.)

The zygomatic arch is the bony bar on the side of the skull in front of the ear. It is formed by two processes meeting: the temporal process of the zygomatic bone in front and the zygomatic process of the temporal bone behind. (OpenStax Anatomy and Physiology 2e, 7.2: The Skull.)

The arch separates two spaces. Above it is the temporal fossa, and below it, deep to the ramus of the mandible, is the infratemporal fossa. Both contain muscles that move the jaw. One of the main muscles that closes the jaw during biting and chewing, the masseter, arises from the zygomatic arch. (OpenStax Anatomy and Physiology 2e, 7.2: The Skull.)

The infratemporal fossa below the arch holds the medial and lateral pterygoid muscles, branches of the mandibular nerve and the maxillary artery. The masseter and temporalis attach to its borders. (TeachMeAnatomy: The Infratemporal Fossa.)

Zygomaticus major and minor, two muscles of facial expression, attach to the lateral surface. Part of levator labii superioris arises from the maxillary border. The temporal fascia attaches to the posterosuperior (temporal) border, and the masseter to the rough posteroinferior border. (Kenhub: Zygomatic bone.)

Three small foramina carry branches of the zygomatic nerve, which comes from the maxillary division of the trigeminal nerve. A canal starts at the zygomatico-orbital foramen on the orbital surface and splits in two. The zygomaticofacial branch exits on the cheek through the zygomaticofacial foramen with a small artery and vein. The zygomaticotemporal branch exits into the temporal fossa through the zygomaticotemporal foramen. (Kenhub: Zygomatic bone.)

The zygomatic nerve itself reaches the orbit from the pterygopalatine fossa through the inferior orbital fissure, next to the infraorbital nerve. (Radiopaedia: Inferior orbital fissure.)

The zygomatic bone ossifies from a single centre at about the eighth week of fetal life. It is occasionally divided into two parts by a horizontal suture. The zygomaticofacial foramen may be double or absent. (Radiopaedia: Zygomatic bone.)

The zygomatic bone is the second most common site of facial fracture. Causes include road traffic collisions and punches. Signs to look for are pain, swelling, a flattened cheek, bleeding under the conjunctiva, double vision (diplopia), altered sensation and a lowered outer corner of the eye. (Kenhub: Zygomatic bone.)

A direct blow to the malar eminence (the point of the cheek) can break the zygomatic bone free at its connections. This zygomaticomaxillary complex (ZMC) fracture is also called a tripod, tetrapod or malar fracture. It involves the zygomatic arch, the inferior orbital rim and maxillary sinus walls, and the lateral orbital rim at the frontozygomatic suture. It accounts for about 40% of midface fractures and is the second most common facial fracture after nasal bone fractures. (Radiopaedia: Zygomaticomaxillary complex fracture.)

Displaced fragments can press on the temporalis muscle and limit mouth opening (trismus), or injure the infraorbital nerve and cause numbness in the skin it supplies. Treatment, if needed, is closed or open reduction to restore the shape of the face, sensation, the position of the eye and chewing. (Radiopaedia: Zygomaticomaxillary complex fracture.)

These terms are easily mixed up. The zygomatic bone is the whole cheekbone. The zygomatic arch is a bridge built from two bones: the temporal process of the zygomatic bone and the zygomatic process of the temporal bone. (OpenStax Anatomy and Physiology 2e, 7.2: The Skull.)

The maxilla also has a zygomatic process, a pyramid-shaped projection where three of its surfaces meet, which joins the zygomatic bone in front. So there are two different zygomatic processes: one on the temporal bone and one on the maxilla. (Radiopaedia: Maxilla.)

The nearest named structures in the 3D model, measured from the centre of each part:

• Optic part of retina · eye & ear
• Lateral rectus · muscular
• Vitreous body · eye & ear
• Sclera · eye & ear
• Choroid · eye & ear
• Lacrimal gland · eye & ear
• Inferior rectus · muscular
• Inferior branch of oculomotor nerve · nervous
• Tarsal plate of lower eyelid · eye & ear
• Lens · eye & ear