Tendinous pattern in the lizard manus

V. ABDALA; A. MANZANO, M.J. TULLI AND A. HERREL

San Luis

Congreso; VIII Congreso Argentino de Herpetología; 2008

Asociación Herpetológica Argentina

  In lizards distinct patterns of the tendinous structures associated with the forearm flexors have been described. In most lizards, the m. flexor digitorum longus ends in a plate with an embedded sesamoid from which tendons run to the terminal phalanx of each digit. This structure is knowing as flexor plate. In many polychrotid lizards, the flexor digitorum longus muscle is continuous with individual tendons running to each digit and no complete flexor plate is present. In most geckos the flexor plate reduces to a tendinous plate without sesamoid. To evaluate the consequences of these differences during locomotion, we compared the use of the fore-arm and hand in locomotion across different substrates in lizards exhibiting three different tendon patterns: Pogona vitticeps, an agamid exhibiting the complete flexor plate; Gekko gecko, a gekkonid with a flexor plate without an embedded sesamoid; and Anolis equestris, a polychrotid with no unique plate, but showing instead independent set of tendons to the digits. We found that the presence of a flexor plate with sesamoid bone prevents digital flexion and creates a rather stiff palmar surface in animals like P. vitticeps. Species with this configuration are unable to grasp narrow branches and show strongly impaired locomotor performance on narrow substrates. Both geckos and Anolis can flex the palms of their hands and their fingers more extensively and do so when moving across narrow substrates. The reduction of the flexor plate in both geckos and Anolis allow these animals to move effectively on narrow substrates.