Sentence:  The vibrissal system of the rat is an example of active tactile sensing, and has recently been used as a prototype in construction of touch-oriented robots. Active vibrissal exploration and touch are enabled and controlled by musculature of the <WSD>mystacial</WSD> pad. 
Meaning of the word marked with <WSD> tags:  Pertaining to the area around the vibrissae on either side of the muzzle of a mammal such as a rodent or cat.