In animal anatomy, Henry's pocket, more formally known as a cutaneous marginal pouch, is a fold of skin forming an open pouch on the lower posterior part of the external ear.[1] The pocket is situated in the approximate location of the antitragus in the human ear. It occurs in a number of mammalian species, including weasels and bats, but is particularly noticeable on the domestic cat, as well as some dog breeds.
The pocket is of unknown function,[2] and it is unclear if it has any at all.[1] However, one hypothesis is that it aids in the detection of high-pitched sounds by attenuating lower pitches, especially when the ear is angled, common for a predator when hunting. Since the pocket occurs in a wide variety of mammalian species, it is likely a conserved feature from their common ancestor.
The pocket is a common area for parasites to gather, and should be checked during a veterinary examination.[3]