The carpal canal is the space between which bones?

• A. The space between the carpal bone and the accessory carpal bone
• B. The space between the radius and ulna
• C. The space between the metacarpal and carpal bones
• D. The space within the carpal tunnel

Answer: (A)

The carpal canal is defined by the space between the carpal bones and the accessory carpal bone, forming a palmar tunnel through which the flexor tendons (and accompanying nerves) pass from the forearm to the digits. This boundary set—carpal bones on one side and the accessory carpal bone on the other—explains why the correct description is between the carpal bones and the accessory carpal bone. The other spaces describe different anatomical relationships: the gap between the radius and ulna is the forearm (antebrachial) space, the space between metacarpal and carpal bones is a joint region, and the idea of the space “within the carpal tunnel” would refer to the contents rather than the boundary defining the canal.