Final answer:
The Carpal Bridge refers to the structure comprising the carpal bones and flexor retinaculum in the wrist, forming the carpal tunnel. This structure is concave due to the U-shaped arrangement of the carpal bones with the flexor retinaculum across the top.
Step-by-step explanation:
The term Carpal Bridge is often used to describe the structure formed by the carpal bones and the flexor retinaculum. The carpal bones are situated in your wrist and are arranged in two rows. The bones in the proximal row, are the scaphoid, lunate, triquetrum, and pisiform bones, while the distal row includes the trapezium, trapezoid, capitate, and hamate bones. These carpal bones create a U-shaped arrangement.
The flexor retinaculum, a strong ligament, spans the top of the carpal bones and is attached laterally to the trapezium and scaphoid bones, and medially to the hamate and pisiform bones. This creates the carpal tunnel, where the carpal bones form the walls and the floor, and the flexor retinaculum forms the roof of this space. Within this tunnel pass the tendons of nine forearm muscles and an important nerve, the median nerve.
Regarding its shape, the carpal tunnel's structure is concave, given that the carpal bones form a curve with the open section facing the flexor retinaculum, while the ligament itself is relatively straight across the wrists' breadth, making up the 'roof' of the tunnel.