Motor points for neuromuscular blockade of the adductor muscle group

We sought to identify the motor nerve points for the adductor muscle group, relate them to specific surface anatomy markings, and define the points in terms of percentage distances along an anatomic reference line. We dissected four muscles in each of 20 legs from 15 skeletally mature, formalin-preserved cadavers. Multiple motor branches occurred in 21 of the 80 muscles dissected, but in only four limbs were they observed for more than one muscle in the group. Motor points (defined as the entry point of the motor branch into the muscle) were identified for each muscle along a reference line from the symphysis pubis to the medial joint line at the distal extent of the medial femoral condyle. The mean motor points and 95% confidence limits were as follows: adductor longus, 31% +/- 1.1%; adductor brevis, 22% +/- 1.8%; adductor magnus, 38% +/- 2.5%; and gracilis, 44% +/- 3.1%. Identification of these motor points facilitates accurate placement of neuromuscular blocking agents, such as botulinum toxin, and may lead to increased clinical efficacy of the block with a reduction in local or systemic side effects.