Location of the Modiolous and the Morphologic Variations of the Risorius and Zygomaticus Major Muscle Related to the Facial Expression in Koreans / 체질인류학회지

Location of the modiolous and morphological variations of the risorius and zygomaticus major muscles are related to the facial expression. The zygomaticus major, levator labii superioris, depressor labii inferioris, depressor anguli oris, risorius, orbicularis oris, buccinator and levator anguli oris muscles insert on the lateral border of the lip, forming the modiolus and mutually associating each other for functioning. The knowledge of the location of the modiolus and surrounding structures are essential to anatomy, prosthodontics, linguistic, physiology and computer simulation based on facial expressions. The authors examined the location of the modiolus, the morphological variations and anatomical relationship of risorius and zygomaticus major muscle to understand the features of the smile of Korean by dissecting 39 cadavers. The location of the modiolus can be showed as three types, according to their height related to the intercheilion horizontal line. Type A that modiolus locate at the intercheilion line was shown in 20 sides (26.0%), type B that modiolus locate above the intercheilion line was shown in 12 sides (15.6%), then type C that modiolus locate under the intercheilion line was shown in 45 sides (58.4%). Most modioli located at 10 ~20 mm lateral to the mouth corner and 0 ~10 mm below the intercheilion line. The risorius muscle was classified into five types by directions of muscle fibers. The depressor anguli oris -risorius type (type I) was observed in 31 sides (40.2%), the platisma -risorius type (type II) was observed in 30 sides (39.0%). Previously, it has been known that zygomaticus major muscle attaches to the modiolus mainly as one bundle. However, the results were clearly shown that two bundles of the zygomaticus major muscle attaches to the modiolus and the position of the mouth edge in 18 sides (23.4%). To sum it up, facial expression is of fundamental importance concerning the morphological variations and these results also can be considered for the facial reconstruction surgery and computer animation department.

Correction of Drooping Mouth Corner due to Cheek Mass by Suspension with Nasolabial Dermal Flap

Benign tumor in the cheek area such as hemangioma, lymphangioma and neurofibroma causes the drooping of affected side soft tissue involving cheek, mouth corner and nasolabial fold due to its heavy weight and bulkiness. The drooping of mouth corner may remain even after partial subcutaneous excision of the mass. The authors suspended the drooped mouth corner with dermal flap which could be elevated through the nasolabial fusiform de-epithelization simultaneously while the mass was removed by the incision. A total of 14 patients with hemangioma, lymphangioma and neurofibroma in the cheek area were operated between February 1998 and November 2001. The age distribution was 5 to 21-years-old and the follow-up period ranged from 5 to 37 months. There were 1 case of epidermal inclusion cyst and 1 case of hematoma, but no infection or facial nerve palsy was reported as complication. The aesthetic results were considered favorable. This technique prevents the drooping of mouth corner or asymmetry of mid-face without remaining any significant deformity at the donor site, and helps to make more normalized facial feature after the removal of soft tissue mass in the cheek.