Physiological cross‐sectional area of the oblique head of the adductor pollicis is greater than its transverse counterpart: Implications for functional testing

ABSTRACT Introduction : Despite structural distinction between the transverse and oblique heads of the adductor pollicis, in vivo testing continues to consider the adductor pollicis as functionally simplistic. As a muscle's architecture is a strong indicator of function, in this study we aimed to determine whether the physiological cross‐sectional areas (PCSAs) of both heads were uniform. Methods : Classical, microdissection, and chemical dissection procedures were conducted on 10 cadaveric left hands to determine structural origin and insertions. Architectural measures of muscle length (L m ), muscle weight (W m ), fascicle length (L f ), sarcomere length (L s ), and pennation angle (θ) were used to calculate PCSA and fascicle length:muscle length ratio (L f :L m ). Results : The oblique head had greater variation in attachments, significantly greater PCSA ( P  = 0.008), and smaller L f :L m ( P  = 0.001) than its transverse counterpart. Conclusions : Muscle architecture suggests the oblique head has greater potential for force generation, and the transverse has greater potential for joint excursion. Muscle Nerve 49 :405–412, 2014