The trapezium is the outmost of the second row of carpal bones. When seen in its dorsal or palmar part it shows a rhombic type; however much open and cropped with the lower angle.
- Among the four protuberances that provide connection to the anterior annular ligament, its anterior surface is differentiable by a vertical notch passed through by the tendon of the flexor carpi radialis muscle and external to the groove by a rim.
- On the internal aspects of the rhomb, meantime a small part on the noticeable lower angle is for the second metacarpal bone, the superior connects with the scaphoid and the inferior with the trapezoid.
- The inferior provides a smooth surface on the external aspects and the superior is free, convex through behind forwards, and concave through without inwards, and is differentiated by a small interval through the side for the second metacarpal bone that articulates with the metacarpal bone of the thumb.
- The trapezium joins with four bones, the scaphoid, trapezoid, and first and second metacarpals.
- joins with the scaphoid at the midcarpal joint
- joins with the trapezoid at its intercarpal joint
- joins with the thumb metacarpal at the carpometacarpal joint of the thumb
Muscle & Tendons
- superficial head of flexor pollicis brevis emerges distally via the tubercle
- the opponens pollicis emerges in between flexor pollicis brevis and abductor pollicis brevis via the tubercle
- the abductor pollicis brevis emerges via the tubercle proximally
- two layers of the flexor retinaculum connect both aspect of the groove of the trapezium
- radial collateral ligament connects to the lateral surface
- capsule of the carpometacarpal joint of the thumb connects to the lateral surface
Provided by distal branches of the radial artery, mainly through the dorsal surface
- The majority of activities that include holding or squeezing are possible due to the thumb’s amazing variety of movement.
- However where the thumb connects the trapezium bone in the wrist, an increased danger of osteoarthritis in the first carpometacarpal (CMC) joint.
- Occasionally the joint ends up being so harmed that surgery is essential.
- Issues commonly begin whenever the thick ligaments that support the joint collectively loosen up, enabling it to slip out of location.
- In time, the articular cartilage that supports the ends of the bones deteriorates, triggering pain and restricting activity.
- Rheumatoid arthritis (RA) and other types of inflammatory arthritis can likewise harm the first CMC joint – likewise called the trapeziometacarpal joint (TMC).