Figure 1.
a-f: Anatomical relations of the musculus adductor pollicis. The fan shaped musculus adductor pollicis stretches in the hand, and originates mainly from the span of the third metacarpal the finger, inserting into the metacarpal joint of the index finger (Fig. 1a, f). The muscle acts around a rotating joint which forms a circular arc around an imaginary pivot A, which lies at the distance rj outside the joint area (Fig. 1e). With the radius rm of this pivot A, the ideal muscle length (lm) lies as an arc between the base and the origin (Fig. 1c). The muscle length lm can be determined through measuring the muscle angle α and the muscle radius rm. (Fig. 1b, c).
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