Whiskers

Cats have specialized facial "touch" hairs called whiskers.  Another name for whiskers is: vibrissae. These whiskers are located on either side of the muzzle, around the eyes and below the chin.  Whiskers provide a "vision by touch".  Whiskers are sensitive enough to detect minor changes in air currents moving around objects. 

Stouter than other body hairs, whiskers are embedded deeper in to the skin.  A whisker rests on a tiny sac of fluid and pivots much like a straw in a soda bottle which makes them extremely sensitive to movement.  When a whisker is brushed against an object or vice versa; something brushes past the whisker - information is passed down to a rich supply of nerve endings that line the sac.

Whisker growth

Vibrissae, or tactile hairs, (commonly termed whiskers), grow in three places on the head:

Supercilary whiskers are located on the eyebrows.
Genal whiskers are found to the back of the cheek.
Mystacial whiskers are on either side of the muzzle and are the longest of the three   sets.

Tiger facial whiskers average around six inches, with those of males being longest and heaviest. Of all the tiger subspecies it is the Sumatran which carries the most generous whiskers.

Whiskers grow and fall out just like nails and fur, but they are around three times thicker than fur and rooted very deeply in areas of the face which have a plentiful supply of blood vessels and nerves.