Sites of Lo.cation: These include the lacertus fibrosus (bicipital aponeurosis, superficial forearm fascia), the Struthers ligament (thickened or aberrant origin of pronator teres from distal humerus), the pronator teres (musculofascial band or compression between 2 muscular heads), and the FDS proximal arch or the flexor digitorum superficialis.
These include pain in the volar forearm that is exacerbated with activity and relieved by rest; decreased sensation in the thumb, index finger, long finger, and radial side of the ring finger; weakness of thenar muscles; and a positive Tinel or Phalen sign in the proximal forearm.
Anterior interosseous syndrome
Causative factors include tendinous bands, a deep head of the pronator teres, accessory muscles (including the Gantzer muscle, which is the accessory head of the FPL), aberrant radial artery branches, and fractures.
These include vague pain in the proximal forearm and weakness of the FPL and FDP to the index finger. Affected persons cannot form a circle by pinching their thumb and index finger (ie, hyperextension of index distal interphalangeal joint and thumb interphalangeal joint). Sensory involvement is not described.