Fig. 4.

Simplified drawing of the bones and selected muscles of the left hand of Ailurus fulgens. Small arrows show the direction of pull of muscular fibres during contraction. Curved arrow shows the direction of rotation of the hand due to the supinatory action of the contracting muscle abductor pollicis longus. (a) Medio-ventral view, extended articulation. (b) Ventral view, partly flexed articulation. Note that even in slight flexion, digit 1 overlaps digit 2, whilst digit 5 overlaps digit 4, showing initial ‘closure of the palm’. apbo, muscles abductor pollicis brevis and oppones pollicis; apl, muscle abductor pollicis longus; fbdm, muscle flexor brevis digitorum manus; p, pisiform; rs, radial sesamoid.