Zygomatic Bone

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Published on February 18th 2022 by

What is the Zygomatic Bone

Zygomatic bone, commonly known as the cheekbone, is a paired, irregular facial bone. It is sometimes known as ‘zygoma’, which is a Greek word, meaning ‘yoke’. This bone forms the cheeks and the lateral walls of the eye sockets or orbits.

Zygomatic Bone

Where is the Zygomatic Bone Located

It is located at the upper and lateral part of the face, forming the prominence of the cheek. More specifically, it is positioned just below each eye, extending upward to the outer side of each eye and downward near the jaw. You can easily feel the bone by touching the ridge above the fleshy area of the cheeks.

Quick Facts

Type Irregular bone
How many are there in the human body 2, paired
Articulates with Temporal bone, frontal bone, maxilla, and sphenoid bones.

Functions

  • It provides structure and strength to the mid-face, forming the cheek.
  • The lower portion of the bone helps the otherwise immobile upper jawbone to do certain movements like speaking, chewing, drinking, coughing, and breathing by joining with it.
  • The bone also protects the arteries, nerves, veins, and organs lying underneath.

Anatomy: Parts and Structure of the Zygomatic Bone

The bone is nearly quadrangular in shape, featuring three surfaces, five borders, and four processes.

Zygomatic Bone Anatomy Labeled

Surfaces

The three surfaces of this bone are: facial, temporal, and orbital.

1. Facial or malar surface

Also known as the lateral surface as it faces outwards. It is smooth and convex, and has a small opening called the zygomaticofacial foramen through which the zygomaticofacial nerve, artery, and vein transmit between the orbit and the face. The zygomaticus major and the zygomaticus minor muscle attach to this surface’s anterior and posterior half.

2. Temporal surface

This posteromedial surface of the bone is commonly called the temporal surface, as it faces towards the temporal bone and infratemporal fossae.

The anterior region of this surface is rough and articulates with the zygomatic or malar process of the maxilla via the zygomaticomaxillary suture.

The surface also spreads over the medial side of the temporal process, forming a part of the lateral wall of the infratemporal fossa.

The temporal surface features the zygomaticotemporal foramen near the base of the frontal process, through which the zygomaticotemporal nerve transmits from the orbit to the temporal fossa.

3. Orbital surface

This smooth and concave surface faces towards the eye orbit, forming the anterolateral part of its floor and the anterior part of its lateral wall. It has a zygomatico-orbital foramen that leads to the zygomatic canal that branches into the zygomaticofacial and zygomaticotemporal canals, opening into the zygomaticofacial and zygomaticotemporal foramina, respectively.

Borders

As mentioned, the bone has five borders that are as follows:

1. Anterosuperior or orbital border

It is smooth, concave, and present between the lateral and orbital surfaces of the bone. This border forms the inferolateral boundary of the eye orbit.

2. Anteroinferior or maxillary border

This border articulates with the upper jawbone, maxilla on both sides via the zygomaticomaxillary suture. It also acts as an attachment site for the levator labii superioris muscle.

3. Posterosuperior or temporal border

It has a sinuous shape, with a convex top and concave bottom part. The border is continuous with the posterior border of the frontal process and the superior border of the zygomatic arch. The zygomaticotemporal foramen is also present on this surface. The temporal fascia also attaches here.

4. Posteroinferior border

It is rough and serves as the attachment site for the masseter muscle.

5. Posteromedial border

It is serrated and articulates with the greater wing of sphenoid bone above via the sphenozygomatic suture and with the orbital surface of the maxilla below. There is a small free surface of the posteromedial margin between these articular surfaces that forms the lateral border of the inferior orbital fissure. This surface also serves as an attachment site for masseter muscle.

Processes

The four processes of this bone include:

1. Temporal process of zygomatic bone

It is a backwardly directed bony projection, having an oblique, serrated end. It originates from the lower half of the bone, articulating with the zygomatic process of the temporal bone to form the zygomatic arch at the temporozygomatic suture.

2. Frontal process of zygomatic bone

It is another projection, originating from the upper margin of the bone. It articulates with the frontal bone above, and the greater wing of sphenoid posteriorly via the zygomaticofrontal, and sphenozygomatic sutures, respectively. The process terminates at the frontozygomatic suture.

This process also features a bony tubercle on its orbital surface called the Whitnall’s tubercle, which serves as an attachment site for the suspensory ligament of the eye, lateral palpebral ligament the levator palpebrae superioris muscle.

3. Maxillary process of zygomatic bone

It arises from the anterosuperior angle of the zygomatic bone. The lower margin of this process articulates with the maxilla.

4. Orbital process of zygomatic bone

This projection forms the lateral wall of the eye orbit and also a part of its floor.

Articulations

From the above discussion, it can be said that the zygomatic bone articulates with the orbital surface and lateral border of the maxilla, greater wing of the sphenoid, zygomatic process of the frontal bone, and zygomatic process of the temporal bone via sutures.

These articulations are collectively referred to as the zygomaticomaxillary complex (ZMC). The ZMC complex involves the following sutures:

  1. Zygomaticomaxillary suture
  2. Zygomaticosphenoidal suture
  3. Zygomaticofrontal suture
  4. Zygomaticotemporal suture

Muscle and Ligament Attachments

  1. Zygomaticus major and zygomaticus minor: These paired zygomaticus muscles attach to the lateral surface of the bone. They bring the upper lips upward and out, thus helping us to smile.
  2. Masseter: This powerful muscle originates at the zygomatic arch. From there, it spreads to the lower jaw, helping to close the jaw.
  3. Lateral palpebrae ligament (part of the levator palpebrae superioris): The ligament of levator palpebrae superioris, which elevates the upper eyelid, is attached to the Whitnall tubercle of frontal process of the zygomatic bone.
  4. Levator labii superioris: It is a triangular band of muscle that stretches from under the eye sockets to the upper lip muscles. Its origin is at both the maxillary process of the zygomatic bone and the zygomatic process of the maxilla bone.

Ossification and Development

The bone ossifies around the eighth week of fetal life, which appears lateral and just beneath the orbit.

References

    1. Zygomatic bone – Kenhub.com
    2. Anatomy, Head and Neck, Zygomatic – Ncbi.nlm.nih.gov
    3. Zygomatic Bone Anatomy – Getbodysmart.com
    4. Zygoma – Radiopaedia.org
    5. Zygomatic Bone – Sciencedirect.com

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