Overview

Ticks are typically acarine in having hexapod larvae and octapod nymphs and adults. The legs are jointed and divided into seven segments: coxa, trochanter, femur, patella, tibia, tarsus and pretarsus.

The terminal pretarsus consists of a basal stalk, paired claws and a membraneous pulvillus. The pulvillus is absent in argasid ticks¹.
The legs are believed to contain flexor and extensor muscle². Within each leg segment, short thick flexor muscles from the outer wall of each joint insert on the articulatory membrane and inner face of the next distal joint. Long, narrow extensor muscle bands originate near the flexor muscles, but extend through the intersegmental cavity to insert on the inner wall of the next distal joint. The action of these muscles allow rotary movement of each leg.
The muscle fibers appear as spindle-shaped or cylindrical structures with sarcomeres. Each muscle fiber is surrounded by a sarcolemma³.

While the legs are primary ambulatory, they may be modified to serve other functions. The legs of Acari may be smooth or variously ornamented and usually possess a number of tactile and sensory hair⁴. On the dorsal surface of tarsus I, e.g., the Haller`s organ, a complex sensory structure is found.