The human hand is a complex structure composed of bones, joints, muscles, tendons, ligaments, nerves, and blood vessels, all working together to allow for a wide range of movement and dexterity.
Bone Structure
The skeletal structure of the hand is comprised of three main parts:
- Carpals: Eight small carpal bones form the wrist, arranged in two rows of four. These bones allow for a significant range of wrist movement.
- Metacarpals: Five long metacarpal bones form the palm. Each metacarpal connects to a finger. The first metacarpal (thumb) is significantly different in structure and movement compared to the other four.
- Phalanges: Fourteen phalanges make up the fingers. Each finger (excluding the thumb) has three phalanges: proximal, middle, and distal. The thumb has only two: proximal and distal.
As stated in the provided reference [1][2], the hand contains:
- Five metacarpals: One for each finger.
- Fourteen phalanges: Three per finger (except the thumb, which has two).
- Four consistently present sesamoid bones: These small, round bones are embedded in tendons and help to reduce friction and improve leverage.
Joints and Movement
The numerous joints in the hand allow for a wide array of movements, including flexion, extension, abduction, adduction, and opposition (thumb). These movements are enabled by the intricate interactions of bones, ligaments, and muscles.
Muscles and Tendons
Numerous muscles in the forearm and hand control the movement of the fingers and wrist. Tendons connect these muscles to the bones, transmitting the force generated by muscle contraction to produce movement.
Nerves and Blood Vessels
A complex network of nerves provides sensation and control to the hand. Blood vessels supply oxygen and nutrients to the tissues, while removing waste products.
