The zygomaticus major muscle (also major zygomatic muscle or simply zygomaticus major, latin: musculus 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 (major and minor) that lie next to each other in the cheek area. An activated zygomaticus major muscle is involved in creating an expression in the human face known as a smile.
The zygomaticus major may be involved in the formation of cheek dimples in some individuals. Before inserting into connective tissue of the mouth corner, zygomaticus major can sometimes divide into two main fibre bundles – a superior bundle, which inserts slightly lateral and superior of the angle of the mouth, and an inferior bundle, which inserts slightly lateral and inferior to the angle of the mouth. In several cadaver dissections, the inferior bundle of the zygomaticus major has been observed to have an attachment along its middle portion. Some researchers believe that when an individual with this anatomical attribute smiles, traction on the skin may create a dimple in the cheek.
The zygomaticus major arises from the zygomatic arch. Its origin site is on the zygomatic bone, just in front of the zygomaticotemporal suture.
The zygomaticus major inserts into the skin of the angle of the mouth, blending with fibers of levator anguli oris, orbicularis oris and more deeply placed muscular fibers.
The main action provided by the zygomaticus major is to lift the angle of the mouth upwards and laterally. Contractions of this muscle produce facial expression of pleasure or laughter.
The nerve supply of the zygomaticus major is received from the zygomatic and buccal branches of the facial nerve (CN VII).
The zygomaticus major is supplied with arterial blood by the facial artery and its superior labial branch.