ABSTRACT
Due to insufficient understanding of the mechanism of the lesser-form cleft lip in clinical practice, the " muscle anatomical reduction" method, which is the general treatment option for the typical cleft lip, is also preferred for the treatment of lesser-form cleft lip, and the repair effect is often far from the patient′s expectation. Based on the anatomical study and clinical observation of the lesser-form cleft lip in more than ten years, the author systematically describes the characteristics regarding the disarrangement of muscle and explains the confusing clinical features of the lesser-form cleft lip. In addition, the pathological mechanism of the lesser-form cleft lip is further classified, and the muscle biomechanical biomimetic repair technique of this defect-" Yin′s nasolabial muscle frame" is proposed to guide clinical operations. This article preliminarily summarizes the author′s new understanding of the lesser-form cleft lip in recent years. The nasolabial Muscle Tension Lines Group(MTLG) theory is applied to analyze and solve puzzles in the lesser-form cleft lip. This process itself also serves as a clinical practice test of the MTLG theory.