Joints of the Wrist, Hand, and Fingers
The large number of bones in the hand and wrist makes for a large number of joints, too. To pass your clinical anatomy course you need to know all about these joints that help you move your wrist, wave your hand, and wiggle your fingers.
The wrist joints
The distal radioulnar joint allows you to flip-flop each hand at the wrist. It’s a synovial joint that allows for a lot of movement; it’s formed where the head of the ulna articulates with the ulnar notch of the radius. This joint contains a fibrocartilaginous disc, and it’s surrounded by a synovial membrane and fibrous joint capsule. Anterior and posterior ligaments support the joint (in other words, these ligaments are close to the front and to the back of the wrist, respectively). The distal radioulnar joint allows you to supinate and pronate your hand and wrist (meaning to turn your palm up or down).
The radiocarpal joint is a synovial joint that’s also found in the wrist. The radius articulates with the first row of carpal bones, except for the pisiform. It has a fibrous joint capsule that’s attached to that distal end of the radius and the ulna and to the carpal bones. This joint allows you to flex and extend your wrist, circumduct (move in a circle), adduct (move the hand sideways, bringing your little finger closer toward the midline of your body), and abduct (move your hand sideways with your thumb moving away from the midline of the body).
The hand joints
The intercarpal joints are synovial joints formed between the individual bones of the proximal row of the carpal bones, between the individual bones of the distal row of carpal bones, and between the proximal and distal rows (the midcarpal joint). Does that seem confusing? These joints don’t have much movement, just a small amount of gliding between the bones.
The carpometacarpal joints are synovial joints between the distal carpal bones and the metacarpals, and the intermetacarpal joints are between the metacarpals. The carpometacarpal joint of the thumb is a saddle-shaped joint between the trapezium and the base of the first metacarpal. The joints have a synovial membrane surrounded by fibrous joint capsules. They’re supported by anterior, posterior, and interosseous (between bone) ligaments. The thumb joint can extend, flex, abduct, adduct, and circumduct. The fifth metacarpal joint is fairly mobile, but the rest don’t have much movement.
The finger joints
The joints of the fingers include the metacarpophalangeal joints and the interphalangeal joints. They’re all synovial joints with synovial membranes and fibrous joint capsules.
Metacarpophalangeal joints: Connecting the proximal phalanges to the metacarpals are condyloid joints with strong palmar and collateral ligaments that allow for movement in different directions (flexion, extension, abduction, adduction, circumduction). You may recognize them as your knuckles.
Interphalangeal joints: These hinge joints allow flexion and extension. They join the heads of the phalanges with the bases of the next distal phalanges. Each finger (digits two through five) has one proximal interphalangeal joint and one distal interphalangeal joint. The thumb has only one interphalangeal joint.