The petrotympanic canal (Huguier canal): Evolutionary, anatomical, and medical perspectives.

The petrotympanic canal, traditionally referred to as Civinini's or Huguier's canal, represents an anatomical passage connecting the middle ear and temporomandibular joint (TMJ). Despite its early description, its structural complexity and functional significance have often been underestimated. In this study, we combined historical, anatomical, and comparative approaches to clarify its morphology, content, and potential evolutionary role. Morphometric analysis of 195 recent human skulls confirmed its constant presence. At the same time, comparative assessment across 27 primate specimens showed that the canal is consistently present in humans and great apes but absent in non-anthropoid, quadrupedal primates. This distribution pattern suggests that the canal may represent a derived feature associated with craniofacial reorganization in bipedal or facultatively bipedal taxa. Clinically, its neurovascular and ligamentous contents highlight potential implications for otological symptoms, TMJ dysfunction, and pathological spread between the middle ear and infratemporal regions. Our results support a broader reconsideration of Civinini's canal, not only as a key anatomical structure but also as a possible marker of evolutionary and functional adaptations.