The zygomaticus major is a paired facial muscle that extends between the zygomatic bone and the corner of the mouth. It is one of the two zygomatic muscles (the other being the zygomaticus minor) that lie next to each other in the cheek area. The zygomaticus major is located lateral to the zygomaticus minor muscle.

The zygomaticus major arises from the lateral (facial) surface of the zygomatic bone and descends anteroinferiorly in an oblique manner towards the angle of the mouth. It inserts at the modiolus and pulls the angle of the mouth upward and laterally, thus contributing to smiling. It is one of the five muscles that elevate the upper lip and its angle. The other muscles include the zygomaticus minor, levator anguli oris, levator labii superioris, and levator labii superioris alaeque nasi.

Origin and insertion of zygomaticus major

The zygomaticus major is a variable muscle, and some people may have cheek dimples due to its variation. Those with cheek dimples may have a divided zygomaticus major. It can split into two parts, forming two separate bundles. The split is known as the duplication or bifurcation of the zygomaticus major. The movement of the skin over this split results in dimples when a person smiles. In cases of a separated zygomaticus major, one bundle connects at the corner of the mouth while the other connects slightly below it.

Origin: lateral (facial) surface of the zygomatic bone, near the zygomaticotemporal suture and lateral to the origin of the zygomaticus minor muscle.

Insertion: modiolus at the angle of the mouth, blending with fibers of the levator anguli oris and orbicularis oris muscles.

Action: pulls the angle of the mouth upward and laterally. In conjunction with other muscles, the contractions of the zygomaticus major produce facial expressions such as pleasure, smiling, and laughing.

Innervation: zygomatic and buccal branches of the facial nerve (CN VII).

Arterial blood supply: superior labial artery of the facial artery.

Venous drainage: superior labial vein, which drains into the facial vein.

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Zygomaticus major