Vibrissen

Vibrissen, commonly known as vibrissae or whiskers, are long, stiff tactile hairs that function as specialized sensory organs in many mammals. A single hair is a vibrissa, while the group of such hairs constitutes the vibrissae on a given area. The term derives from Latin and reflects their whisker-like appearance.

Anatomically, each vibrissa grows from a deep follicle that extends into the dermis and is often associated with a blood sinus. The follicle is richly innervated by trigeminal nerve fibers and is enclosed in a muscular capsule that can move the hair. The shaft is thicker and stiffer than ordinary fur, enhancing its role as a sensory probe. The vibrissal apparatus converts mechanical deflection into neural signals that the brain can interpret.

Vibrissae are most prominent in regions such as the mystacial area on the muzzle, where many hairs form an array that can be actively whisked. Other clusters occur on the nose, cheeks (genal), around the eyes (supraorbital), and even on the wrists (carpal vibrissae) in some species. The exact number and arrangement vary by species and ecological niche, with larger or more numerous arrays in nocturnal, fossorial, or aquatic mammals.

Functionally, vibrissae provide high-resolution tactile information, including contact, texture, shape, and distance to objects. They aid navigation in darkness or murky environments and assist in hunting and obstacle avoidance. Whisking behavior—rhythmic, voluntary movement of the vibrissae—helps the animal sample its surroundings in real time. In humans, vibrissae are vestigial and not used as a primary sensory system; the study of their neural processing, particularly in rodents, has advanced understanding of somatosensory representation.