Zygomaticus Major
Facial Expression · Head & Neck
The zygomaticus major is a slender muscle of facial expression that is the principal muscle of smiling. It arises from the zygomatic bone on the cheek and runs downward and forward to insert at the angle of the mouth, where it blends with the orbicularis oris and neighbouring muscles. Its contraction draws the angle of the mouth upward and laterally, producing the smile and contributing to laughter. It is supplied by the buccal and zygomatic branches of the facial nerve (CN VII), the common motor nerve of all the muscles of facial expression.
Origin, Insertion, Action & Nerve
Origin
Zygomatic bone
Insertion
Angle of the mouth
Action
Draws the angle of the mouth superolaterally (smiling)
Nerve
Buccal and zygomatic branches of facial nerve (CN VII)
Attachments explained
The Zygomaticus Major is defined first by where it attaches. Its origin is the more fixed anchor, usually the proximal or more stable end that stays put during contraction, while its insertion is the more mobile point that is pulled toward the origin when the muscle shortens.
Origin
Zygomatic bone
Insertion
Angle of the mouth
Action & function
When the Zygomaticus Major contracts, it produces the following movement: Draws the angle of the mouth superolaterally (smiling).
As part of the Facial Expression group of the Head & Neck, it works alongside neighbouring muscles to generate smooth, coordinated movement and to stabilise the structures it acts on.
Nerve supply & clinical relevance
The Zygomaticus Major receives its nerve supply from the Buccal and zygomatic branches of facial nerve (CN VII).
Because a muscle can only contract when its nerve is intact, injury to the Buccal and zygomatic branches of facial nerve can weaken or paralyse the Zygomaticus Major, impairing the movements it normally produces (draws the angle of the mouth superolaterally (smiling)). This is why knowing the innervation is central to localising nerve lesions in clinical practice.
How to study the Zygomaticus Major (the OIANS method)
Remember the zygomaticus major as the smile muscle and reason its action straight from its line of pull. Running from the cheekbone down to the corner of the mouth, it can only draw that corner up and out, which is exactly the movement of smiling; feeling the corner of your own mouth lift toward the cheekbone makes the action concrete.
Keep it among the facial-expression muscles supplied by the facial nerve (CN VII), so a facial palsy flattens the smile on the affected side. Anchoring its origin to the zygomatic bone, which gives the muscle its name, and its insertion at the angle of the mouth is a simple way to distinguish it from the many other muscles converging on the lips.
Frequently asked questions
Where is the Zygomaticus Major located?
The Zygomaticus Major is a muscle of the Facial Expression group, located in the Head & Neck.
What is the origin of the Zygomaticus Major?
Zygomatic bone
What is the insertion of the Zygomaticus Major?
Angle of the mouth
What movements does the Zygomaticus Major produce?
Draws the angle of the mouth superolaterally (smiling)
What nerve supplies the Zygomaticus Major?
Buccal and zygomatic branches of facial nerve (CN VII)
Is the Zygomaticus Major free to study in OIANS?
The Zygomaticus Major is always free to browse. Its full origin, insertion, action and nerve details are open to everyone in the Muscle Directory. Quiz and Flashcard practice for the Head & Neck is part of the one-time Lifetime upgrade, though; only the Upper Limb decks are free to test yourself on.
Related muscles
Study the Zygomaticus Major
Test yourself on Head & Neck muscles with interactive quizzes and flashcards in the free OIANS app.
Quiz yourself → Flashcards Open the OIANS app
Browsing is always free. A one-time Lifetime unlock adds every region's quizzes, flashcards, progress tracking and explore tools.