a compromised adductor pollicis muscle. In neuromuscular monitoring, the ulnar nerve is stimulated and the strength of adductor pollicis contraction is measured. Other animals The adductor pollicis evolved from the contrahens I muscle as man's ancestors' thumbs and big toes became opposable. It might also contain an element of the thumb's interosseous muscle. In the Pan-Homo LCA the oblique head of the adductor pollicis probably had a relatively small physiological cross sectional area (PCSA) and both heads probably acted as extensors and adductors at the carpometacarpal joint. In humans the PCSA of the oblique head is relatively enlarged and both heads act as flexors at this joint. See also Adductor hallucis muscle Additional images References Muscles of the upper limb Hand