The zygomaticus major muscle is a

muscle Skeletal muscles (commonly referred to as muscles) are organs of the vertebrate muscular system and typically are attached by tendons to bones of a skeleton. The muscle cells of skeletal muscles are much longer than in the other types of mus ...

of the

human body The human body is the structure of a human being. It is composed of many different types of cells that together create tissues and subsequently organ systems. They ensure homeostasis and the viability of the human body. It comprises a hea ...

. It extends from each zygomatic arch (

cheekbone In the human skull, the zygomatic bone (from grc, ζῠγόν, zugón, yoke), also called cheekbone or malar bone, is a paired irregular bone which articulates with the maxilla, the temporal bone, the sphenoid bone and the frontal bone. It is si ...

) to the corners of the mouth. It is a

muscle of facial expression The facial muscles are a group of striated skeletal muscles supplied by the facial nerve (cranial nerve VII) that, among other things, control facial expression. These muscles are also called mimetic muscles. They are only found in mammals, alth ...

which draws the angle of the mouth superiorly and posteriorly to allow one to

smile A smile is a facial expression formed primarily by flexing the muscles at the sides of the mouth. Some smiles include a contraction of the muscles at the corner of the eyes, an action known as a Duchenne smile. Among humans, a smile expresses ...

. Bifid zygomaticus major muscle is a notable variant, and may cause cheek dimples.

Structure

The zygomaticus major muscle originates from the upper margin of the temporal process, part of the lateral surface of the

zygomatic bone In the human skull, the zygomatic bone (from grc, ζῠγόν, zugón, yoke), also called cheekbone or malar bone, is a paired irregular bone which articulates with the maxilla, the temporal bone, the sphenoid bone and the frontal bone. It is s ...

. It inserts into tissue at the corner of the

mouth In animal anatomy, the mouth, also known as the oral cavity, or in Latin cavum oris, is the opening through which many animals take in food and issue vocal sounds. It is also the cavity lying at the upper end of the alimentary canal, bounded on ...

Nerve supply

The zygomaticus major muscle is supplied by a

buccal branch The buccal branches of the facial nerve (infraorbital branches), are of larger size than the rest of the branches, pass horizontally forward to be distributed below the orbit and around the mouth. Branches The ''superficial branches'' run beneath ...

and a zygomatic branch of the

facial nerve The facial nerve, also known as the seventh cranial nerve, cranial nerve VII, or simply CN VII, is a cranial nerve that emerges from the pons of the brainstem, controls the muscles of facial expression, and functions in the conveyance of taste ...

(VII).

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. Usually a single unit,

dimple A dimple, also called a gelasin (, ) is a small natural indentation in the flesh on a part of the human body, most notably in the cheek. Numerous cultures believe that cheek dimples are a good luck charm that entices people who perceive them a ...

s are caused by variations in form. It is thought that

cheek The cheeks ( la, buccae) constitute the area of the face below the eyes and between the nose and the left or right ear. "Buccal" means relating to the cheek. In humans, the region is innervated by the buccal nerve. The area between the insi ...

dimples are caused by bifid zygomaticus major muscle.

Function

The zygomaticus major muscle raises the corners of the mouth and draws them posteriorly when a person

smiles The simplified molecular-input line-entry system (SMILES) is a specification in the form of a line notation for describing the structure of chemical species using short ASCII strings. SMILES strings can be imported by most molecule editors ...

. 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.

Image

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