The zygomaticus minor muscle is a muscle of facial expression. It originates from the zygomatic bone, lateral to the rest of the levator labii superioris muscle, and inserts into the outer part of the upper lip. It draws the upper lip backward, upward, and outward and is used in smiling. It is innervated by the facial nerve (VII). Structure The zygomaticus minor muscle originates from the zygomatic bone. It inserts into the tissue around the upper lip, particularly blending its fibres with orbicularis oris muscle. It lies lateral to the rest of levator labii superioris muscle, and medial to its stronger synergist zygomaticus major muscle. It travels at an angle of approximately 30°. It has a mean width of around 0.5 cm. Nerve supply The zygomaticus minor muscle is supplied by the buccal branch of the facial nerve (VII). Variation The zygomaticus minor muscle may have either a straight or a curved course along its length. It may attach to both the upper lip and the lateral alar region. It may be underdeveloped in some people, with its role taken over by nearby synergists. These synergists rarely change shape or position, but any difference in smile is usually imperceptible. Function The zygomaticus minor muscle draws the upper lip up, back, and out, such as during smiling. History The zygomaticus minor muscle is sometimes referred to as the "zygomatic head" of the levator labii superioris muscle. Images See also Zygomaticus major muscle Zygomatic bone References External links PTCentral Muscles of the head and neck