The human hand is an incredible tool capable of various movements and actions. This remarkable dexterity is made possible by the harmonious collaboration of muscles, joints, tendons, ligaments, nerve fibers, and bones. Within the human body, the hand alone consists of 27 small and delicate bones, which make up nearly 25% of the total 206 bones. Alongside these bones, the hand is also composed of 14 joints, eight carpal bones, five metacarpal bones, and 14 phalanges. Together, these structures form the underlying framework that supports and facilitates the hand’s interactions with surrounding tissues.
The Hand’s Joint Structure
The hand and wrist rely on synovial joints for their movement, just like larger joints such as the knee. These joints are characterized by the presence of articular cartilage that covers the ends of long bones. This cartilage, along with the synovial fluid found in the joint cavities, plays a crucial role in protecting the bones during articulation. In the hand, two types of joints are primarily involved in movement: the metacarpophalangeal (MCP) joints, which include the knuckles, and the interphalangeal (IP) joints, located between the bones that form the fingers.
Carpals
The carpal bones are a group of eight bones that are connected by ligaments and arranged in two rows of four. These bones not only connect with each other but also with the bones in the wrist, creating multiple joints between the hand and forearm. The lower wrist joint is formed by the scaphoid and lunate carpal bones, as well as the radius bone in the forearm. The other part of this lower joint is formed by the two rows of carpal bones.