[The anatomic study and clinical application of the premasseter space].

Objective: Through the anatomy study of the premasseter space, further improved the anatomic knowledge of the premasseter space and explored its application in rhytidectomy, in order to reduce the risk of facial nerve injury. To further improve the anatomic knowledge of the premasseter space and to determine its application in rhytidectomy.

Methods: The anatomy of the premasseter region was investigated in 12 fresh cadaver (24 hemi-faces) dissections;810 patients of SMAS rhytidectomy procedures were observed.

Results: ①There were several soft tissue spaces superficial to the masseter muscle, and the boundaries were strengthened by retaining ligaments. Adjacent spaces were separated by numerous weak fiber membranes connecting the SMAS and masseter fascia.② The space was further divided into two parts; one part was located under the platysma and another part was under the aponeurosis of SMAS. The former part was easier to identify and dissect. ③ The relaxation, expansion, and sliding of the space is an important reason in the face sags with aging, which is referred to as the layered ptosis theory.

Conclusions: The soft tissue space superficial to the masseter muscle have two different characteristics. The different nature of the two parts of the space can easily mislead dissection to the wrong layer, which is the important anatomical factors for the risk of facial nerve damage in rhytidectomy. The layered ptosis theory seem to better explain the process of aging. The primary treatment of aged face was facial space dissection and tighten.