The muscular system of Amblyomma americanum larvae from the morphological and functional point of view is studied. The capitulum is moved by four muscles: two depressors and two levators. Chelicerae have three muscles: retractor, flexor and digit extensor. Each segment of the palp presents two muscles - flexor and extensor - which permit the lateral movements of the palp. Legs have a pair of muscles (flexor and extensor) with opposing action, related to each segment; coxae present two series more of muscles, the abductor and the adductor. The most evident systems of the body are dorso-ventral and they are inserted in the ventral side of the body