Zygomaticus minor muscle
Zygomaticus minor is a thin paired facial muscle extending horizontally over the cheeks. It belongs to a large group of muscles of facial expression called the buccolabial group. Besides zygomaticus minor, this group also contains levator labii superioris alaeque nasi, levator labii superioris, zygomaticus major, levator anguli oris, risorius, depressor labii inferioris, depressor anguli oris, mentalis, orbicularis oris, incisivus superior and inferior, and buccinator muscles.
All these muscles work together to control the shape, posture and movements of the lips. In the array of their respective actions, zygomaticus minor elevates the upper lip, thus exposing the maxillary teeth. The function of this movement is to facilitate speech, as well as to enable various facial expressions, such as smiling.
|Origin||(Anterior part of) Lateral aspect of zygomatic bone|
|Insertion||Blends with muscles of upper lip (medial to zygomaticus major muscle)|
|Action||Elevates upper lip, exposes maxillary teeth|
|Innervation||Zygomatic and buccal branches of facial nerve (CN VII)|
|Blood supply||Superior labial branch of the facial artery|
This article will discuss the anatomy and function of 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.
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.
Zygomaticus minor is innervated by the zygomatic and buccal branches of facial nerve (CN VII).
Vascular supply to zygomaticus minor comes from the superior labial branch of facial artery.
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”.