OBJECTIVETo study the anatomy of angular nerve (AN), so as to provide safe approach for the denervation surgery of corrugator supercilii, depressor supercilii and procerus.

METHODS10 fresh cadaver (20 sides)were perfused and fixed with formalin. Dissection was performed in the 10 x operating microscope. The plexus of the zygomatic branch and the buccal branch were detected to confirm the AN. The relationship of AN with the surrounding blood vessels was observed. We tracked AN until it entered corrugator supercilii, depressor supercilii and procerus.

RESULTS(1) AN was classified into I, II, III type according to its formation pattern. Type I (20%, 4/20 sides) AN is single, which is mainly from the plexus of buccal branch plus the zygomatic branch from the orbicularis oculi muscle. In type II (20%, 4/20 sides), the single AN was formed by buccal branch plexus and zygomatic branch plexus in the "Four Muscle Gap". In type III (60%, 12/20 sides), the AN had two branches in the "Four Muscle Gap". (2) The three types AN passed inferior to the support ligament at the suborbital part, and then transversed medial to the support ligament at the medial canthus, along the vessels of medial canthus. (3) The branch of AN enters the depressor supercilii or procerus 2.19 to 4.28 mm above the medial canthus ligament. The backward branch enters the levator labii superioris alaeque nasi 6.89 to 9.38 mm below the medial canthus ligament.

CONCLUSIONSThe approach of denervation surgery for AN should be performed medial to the support ligation, between 2.19 mm above the medial canthus and 6.89 mm below the medial canthus.