Background The posterior cephalic soft triangle is formed between the posterior cephalic border of the lower lateral cartilage, posterior caudal border of the upper lateral cartilage, and the caudal edge of the nasal bone. PCST is an important component of the external nasal valve which provides resistance against dynamic collapse. Objectives The objective of this study was to describe the anatomy of the PCST and to demonstrate its anatomic variations, dynamic interplays, and surgical implications. Methods A retrospective review was conducted of 310 primary and 42 secondary cases who underwent extended open approach rhinoplasty by the first author. The structures that create the PCST of the nose were preserved unless resection/displacement of them was absolutely necessary. Whenever an external nasal valve pathology was found, it was corrected with one or combination of the following maneuvers: triangular PCST onlay graft, caudal bone outfracture, alar rim graft, lateral crural strut graft. Results Twenty-four non-consecutive cases were identified in which PCST was intraoperatively confirmed to be weak or deformed. The most common pathology in the PCST was overresection of the posterior segments of the LLC during primary surgery (54.1%), followed by en bloc medialization of the PCST (33.3%). Triangular onlay grafting of the PCST was the most common corrective surgical intervention (83.3%), followed by corrective lateralization of caudal edge of nasal bone (29.1%). External valve function has been restored in 21 (87.5%) cases. Conclusions PCST of the nose is an important anatomic landmark which has esthetic and functional significance in rhinoplasty.