The narial musculature of Alligator mississippiensis Alligator mississippiensis Alligator mississippiensis : Can a muscle be its own antagonist?

摘要

Abstract The crocodilian naris is regulated by smooth muscle. The morphology of this system was investigated using a combination of gross, light microscopic, and micro‐CT analyses, while the mechanics of narial regulation were examined using a combination of Hall Effect sensors, narial manometry, and electromyography. Alligator mississippiensis , like other crocodilians, routinely switches among multiple ventilatory mechanics and does not occlude the nares during any portion of the ventilatory cycle. In a complex that is unique among vertebrates, a single block of smooth muscle functions in dilation when active, and in constriction when passive. The alligator nares may include one of the best examples of a muscle that functions in “pushing” as well as “pulling.” The central muscle for narial regulation, the dilator naris, can legitimately be viewed as its own antagonist.