Zygomaticus minor muscle

Origin and insertion

Zygomaticus minor originates from the anterior portion of the lateral surface of zygomatic bone, just posterior to the zygomaticomaxillary suture. It courses inferoanteriorly towards the lips, passing obliquely across the lateral surface of the maxilla. The muscle inserts medial to the zygomaticus major muscle by blending with the muscles of the upper lip; levator labii superioris and orbicularis oris. 

Relations

Zygomaticus minor lies deep to the subcutaneous fat of the face and superficial to the levator anguli oris muscle. Zygomatic branches of facial nerve course between the adjacent surfaces of these two respective muscles. 

Zygomaticus minor is placed in the same plane as, and superior to, zygomaticus major and sits inferiorly to orbicularis oculi. The labial attachment of the muscle is lateral to that of levator labii superioris alaeque nasi. With levator labii superioris alaeque nasi, zygomaticus minor bounds a triangular space through which the levator labii superioris muscle passes.

Innervation

Zygomaticus minor is innervated by the zygomatic and buccal branches of facial nerve (CN VII).

Blood supply

Vascular supply to zygomaticus minor comes from the superior labial branch of facial artery.

Function

Zygomaticus minor is a direct tractor of the upper lip, together with levator labii superioris alaeque nasi and levator labii superioris. This means that it inserts to the upper lip directly, thus acting upon it without an intermediary. 

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Working in synergy with the above mentioned direct labial tractors, zygomaticus minor elevates the upper lip and deepens the nasolabial lines. The consequential function of zygomaticus minor is to contribute to several facial expressions; smiling, smugness and contempt. Zygomaticus minor also aids speech, particularly if the intention is to emphasize certain sounds such as the letter “E”.