Skills - Ortho Imaging P1

Anatomy of Hand and Wrist Bones

The hand and wrist are composed of several bones arranged in intricate ways, providing structure and stability while allowing for a great range of motion. Understanding these bones and their functions is essential for medical professionals, patients recovering from injuries, or anyone interested in human physiology.

Carpal Bones

Carpal bones are found between the forearm and the metacarpals. There are eight carpal bones in total, comprising two rows: the proximal row and the distal row. These small flat bones have varying shapes and sizes, and they interlock with each other to form a complex system of joints called the carpus. The carpus provides support for the base of the thumb and forms the wrist joint with the radius and ulna.

Proximal Row of Carpal Bones

Including the scaphoid, lunate, triquetral, pisiform, and trapezium and trapezoid bones, the proximal row is located closest to the forearm. The scaphoid bone, also known as the navicular bone, lies directly under the radius and is among the most commonly fractured carpal bones due to its location and thinness. The lunate bone fits into a groove on the radius and replaces the distal end of the ulna during supination. It has a concave surface which articulates with the radial styloid process. The triquetral bone, named after its horseshoe shape, is medial to the lunate. Its posterior part articulates with the hamulus of the ulna, forming the radio-ulnar joint. The pisiform bone overlies the triquetral bone and is one of the few sesamoid bones in the body, formed by the flexor carpi ulnaris tendon passing over it. The trapezium and trapezoid bones help form the first carpometacarpal joint at the base of the thumb.

Distal Row of Carpal Bones

This group includes the capitate, hamate, and lateral and medial uncinate bones. The capitate bone sits between the lunate and the hamate bone. The hamate bone's medial side connects with the hook of the hamulus of the ulna, creating another radioulnar joint. The lateral and medial uncinate bones are smaller bones situated on either side of the scapholunate ligament.

Metacarpal Bones

Metacarpal bones are the five long bones found between the wrist and the phalanges of the hand. They are numbered 1 through 5 from the radial side of the hand. The first metacarpal bone forms the base of the thumb, while the rest provide the foundation for the fingers. The metacarpal bones are connected to the wrist by the carpometacarpal joints. The first metacarpal bone is different in shape and size, giving the thumb its unique range of motion.

Phalanges

Phalanges are the bones found in the fingers and thumb of the hand. There are three phalanges in each finger, numbered 1-3 from proximal to distal. The proximal phalanges connect to the metacarpal bones, the middle phalanges are the longest of the three, and the distal phalanges are the smallest. The thumb has only two phalanges, the proximal and distal, due to a reduced middle phalanx.

Bones of the Hand

The bones of the hand include the bones mentioned above, such as the carpal bones, metacarpal bones, and phalanges, as well as the wrist and finger bones. These bones work together to provide the structure, stability, and flexibility necessary for the hand's function. Understanding their anatomy can help medical professionals in diagnosing and treating injuries, as well as providing insight into the overall health and function of the hand and wrist.

Test your knowledge of the intricate arrangement and functions of the bones in the hand and wrist. Learn about the carpal bones, metacarpal bones, phalanges, and how they work together to provide structure, stability, and flexibility essential for hand function.