Corpus: Levator labii superioris muscle

The levator labii superioris muscle is a superficial muscle located in the anterior cheek region, or along the nasal slope, that elevates the upper lip. It is part of the facial expression (mimic) musculature.

The levator labii superioris muscle consists of three distinct fiber strands or muscle heads:

1. Medial fibers (Caput angulare): This portion is identical to the levator labii superioris alaeque nasi muscle. It originates from the frontal process of the maxilla and runs obliquely downward, splitting into two sections. One set of fibers inserts into the wing cartilage (cartilago alaris major) and the skin of the nasal wing, while the other set radiates into the lateral part of the upper lip, blending with fibers of the orbicularis oris muscle.
2. Middle fibers (Caput infraorbitale): These fibers originate from the lower edge of the orbit, just above the infraorbital foramen. They extend downward and insert into the muscle tissue of the upper lip, between the canine and the caput angulare.
3. Lateral fibers (Caput zygomaticum): This portion is identical to the zygomaticus minor muscle. It originates from the bony surface of the zygomatic bone, just behind the zygomaticomaxillary suture, and extends downward and medially to the upper lip.

In some anatomical references, only the middle portion is specifically referred to as the levator labii superioris muscle, while the other two portions are identified as separate muscles.

The levator labii superioris muscle is innervated by the buccal and zygomatic branches of the facial nerve (cranial nerve VII).

The primary function of the levator labii superioris muscle is to elevate the upper lip.