Capitate fractures occur together with fractures of another carpal bone, the scaphoid. The abductor pollicis brevis originates on the scaphoid tubercle and the flexor retinaculum. The scaphoid is situated between the proximal and distal rows of carpal bones. The scaphoid bone is one of the carpal bones of the wrist. On its ulnar surface are found the trapezoid and scaphoid bones. The abductor pollicis brevis (APB) originates on the scaphoid tubercle and the flexor retinaculum. A scaphoid fracture is a break of the scaphoid bone in the wrist. In this state, the distance between the scaphoid and lunate bones is increased. Non union can also occur from undiagnosed or undertreated scaphoid fractures. People with scaphoid fractures generally have snuff box tenderness. If not treated correctly non-union of the scaphoid fracture can lead to wrist osteoarthritis. "Avascular necrosis" (AVN) is a common complication of a scaphoid fracture. Scaphoid fractures are most commonly caused by a fall on an outstretched hand. The scaphoid serves as a link between the two rows of carpal bones. Scaphoid fractures are often diagnosed by PA and lateral X-rays.