The anatomic detail of the interosseous membrane was studied by dissection of 20 preserved cadaveric specimens. The interosseous membrane was found to be a complex structure consisting of a central band, accessory bands, a proximal interosseous band, and membranous portions. The central band, a stout ligamentous structure, was found in all specimens. Fibers of the central band originate on the radius and are oriented distal and ulnar an average of 21 degrees to the longitudinal axis of the ulna. Accessory bands were of less substance than the central band but were present in all specimens. The number of accessory bands ranged from 1 to 5. The proximal interosseous band is located on the dorsal surface only, and its fibers run counter to the central band. It shares a point of origin with the central band on the radius. This structure was present in 17 of 20 specimens. Since the central band was the most dominant and consistent structure, we chose to analyze the strain in the central band in 6 preserved specimens. Maximum strain in the central band of the intact specimen occurs in neutral forearm rotation. Once the radial head is removed, the percent strain universally increases throughout the arc of forearm rotation and peak strain shifts to pronation.