<unk>  usually refers to a benign growth of the conjunctiva.  Alternately, it refers to any winglike triangular membrane occurring in the neck, eyelids, knees, elbows, ankles or digits.  An example is popliteal<unk>  syndrome, which affects the legs. The term comes from the Greek word pterygion meaning "wing". When associated with the conjunctiva, a<unk>  commonly grows from the nasal side of the sclera. It is associated with, and thought to be caused by ultraviolet-light exposure (e.g. sunlight), low humidity, and dust. The predominance of pterygia on the nasal side is possibly a result of the sun's rays passing laterally through the cornea where it undergoes refraction and becomes focused on the limbic area.  Sunlight passes unobstructed from the lateral side of the eye, focusing on the medial limbus after passing through the cornea.  On the contralateral side, however, the shadow of the nose medially reduces the intensity of sunlight focused on the lateral/temporal limbus.
Pterygium
Trapezium 
Maxilla
Hard palate
Tip of the tongue
Adenoid
Cauliflower ear
Canthus 