REGIONAL ANATOMY OF CORRUGATOR SUPERCILII MUSCLE, SUPRATROCHLEAR NERVE & SUPRAORBITAL NERVE

To clarify the exact regional anatomy of corrugator supercilii muscle and relationship between corrugator supercilii muscle, supratrochlear nerve and supraorbital nerve, we dissected 17 Korean adult cadavers(33 sides). The results were as follows. 1. The distance between nasion and the origin of corrugator supercilii was 7.6mm in average. 2. In average the width of corrugator supercilii at the origin was 7.1mm at the insertion was 18.3 mm, the length of the corrugator supercilii was 26.2mm and the angle between corrugator supercilii and horizontal line was 38.3˚. 3. We classified the variations in branching patterns of supratrochlear nerve into 4 types. Type I was classified as a single non-branching supratrochlear nerve, type II as a dividing supratrochlear nerve, type III as a converging supratrochlear nerve and type IV as a complex type. Each of these 4 types comprised 57.6%, 33.3%, 3.0% and 6.1%, respectively. 4. The variations in the location of supratrochlear nerve as it passes through the corrugator supercilii muscle was classified into 4 types. Type I was classified as a single supratrochlear trunk ascending over the muscle, type II as a single supratrochlear piercing through the muscle, type III as a branched supratrochlear nerve where one branch ascends over the muscle and the other pierces through, and type IV as a branched supratrochlear nerve where both branches pierce the muscle. Each types made up 33.3%, 27.2%, 21.2% and 18.2% respectively. 5. The average distance between the origins of corrugator supercilii muscle and supratrochlear nerve was 8.1 mm and there was much variations in this distance among the cases. In 32.6%, this distance was found to he more than 10 mm. However, the distance between the midline and the site supratrochlear nerve penetrating the corrugator supercilii muscle was found to he relatively uniform, 13.8 mm. 6. We observed that the supraorbital nerve passed underneath the corrugator supercilii muscle in our cases. This nerve was either a non-branching type or a branching type with 2 main branches. The former made up 37.7% of the cases where the latter made up the rest 62.3%. The distantly from the midline to the most medially located branch was relatively uniform, distance of 24.0 mm. From the resuits we obtained, it would be safe to resect or incise the corrugator supercilii muscle within 1 cm medial to the supraorbital nerve which can be easily identified by surface anatorny or by inspection through endoscopy.ope