Henry’s Pocket is a feature found on the ears of many domestic cats, though it often goes unnoticed by their owners. This small, unique anatomical structure is also present in a variety of other mammals, including some canids, bats, and weasels, indicating it is an evolutionarily conserved trait. While a common, non-threatening characteristic for cats, its exact purpose has been the subject of scientific speculation.
Identification and Location
The technical term for Henry’s Pocket is the cutaneous marginal pouch. This structure is easily identified as a small slit or fold of skin located on the lower, outer edge of the cat’s external ear flap, known as the pinna. If you trace the contour of your cat’s ear down toward the base, you will find this triangular pouch positioned on the posterior, or back and bottom, side. While prominent on most domestic cat breeds, its size and depth can vary slightly from one individual to another.
Proposed Biological Function
The existence of the cutaneous marginal pouch in multiple species with exceptional hearing suggests it plays a role in acoustics, though its function is not definitively proven. One prevailing theory is that the fold assists in capturing and processing high-frequency sounds. Cats possess one of the broadest hearing ranges among mammals, capable of detecting sounds up to 85 kilohertz.
It is hypothesized that the pocket may act as a passive acoustic chamber, modifying sound waves before they enter the ear canal. This specialized morphology may help to attenuate lower-pitched background noise, allowing the cat to focus on the movements of prey. Additionally, the pouch may provide extra flexibility to the pinna, facilitating the cat’s ability to rotate its ears independently and flatten them backward more efficiently.
Health and Care Considerations
While the cutaneous marginal pouch is a normal anatomical feature, its folded shape can make it a collection point for various debris. Due to the indentation, the pocket may accumulate dirt, wax, or exfoliated skin cells. This necessitates routine inspection by owners to ensure the area remains clean and healthy.
The pocket is also a common location where external parasites, such as ticks, may hide or attach. When checking your cat’s ears, gently examine the fold for any signs of redness, unusual discharge, or a foul odor, which could indicate an infection. Cleaning this area should be done externally and gently, using a soft cloth or cotton ball, and avoiding the deep insertion of any cleaning tools into the ear canal.