The zygomaticus major muscle is a

muscle Muscle is a soft tissue, one of the four basic types of animal tissue. There are three types of muscle tissue in vertebrates: skeletal muscle, cardiac muscle, and smooth muscle. Muscle tissue gives skeletal muscles the ability to muscle contra ...

of the face. It arises from either zygomatic arch (

cheekbone In the human skull, the zygomatic bone (from ), also called cheekbone or malar bone, is a paired irregular bone, situated at the upper and lateral part of the face and forming part of the lateral wall and floor of the orbit (anatomy), orbit, of t ...

); it inserts at the corner of the mouth. It is innervated by branches of the facial nerve (cranial nerve VII). It is a muscle of facial expression, which draws the angle of the mouth superiorly and posteriorly to allow one to smile. Bifid zygomaticus major muscle is a notable variant, and may cause cheek dimples.

Structure

Origin

The zygomaticus major muscle originates from the superior margin of the lateral surface of the temporal process of zygomatic bone, just anterior to the zygomaticotemporal suture.

Insertion

It inserts at the corner of the

mouth A mouth also referred to as the oral is the body orifice through which many animals ingest food and animal communication#Auditory, vocalize. The body cavity immediately behind the mouth opening, known as the oral cavity (or in Latin), is also t ...

by blending with the levator anguli oris muscle, the orbicularis oris muscle, and the deeper muscular structures.

Nerve supply

The muscle receives motor innervation from the buccal branch and zygomatic branch of the facial nerve (CN VII).

Vasculature

The muscle receives arterial supply from the superior labial artery.

Variation

The zygomaticus major muscle may occur in a bifid form, with two fascicles that are partially or completely separate from each other but adjacent. It is thought that cheek dimples are caused by bifid zygomaticus major muscle.

Function

The zygomaticus major muscle raises the upper lip to bare the upper teeth. It additionally deepens and raises the nasolabial furrow. Acting in conjunction with other muslces of facial expression that elevate the lip, it curls the upper lip to produce facial expressions such as smiling, disdain, contempt, or smugness.

Physiology

The average muscle can contract with a force of 200 g.

Clinical significance

The zygomaticus major muscle may be used in

reconstructive surgery Reconstructive surgery is surgery performed to restore normal appearance and function to body parts malformed by a disease or medical condition. Description Reconstructive surgery is a term with training, clinical, and reimbursement implicat ...

to replace lost tissue, such as with injuries to the lips.

Additional images

File:Zygomaticus major muscle animation small.gif, Position of zygomaticus major muscle. Animation. File:Zygomaticus.png, Muscles of the head, face, and neck. Zygomaticus major shown in red.

References

External links

Zygomaticus Major

Clips of muscle action
{{Authority control Muscles of the head and neck