Anatomy of the Hand and Wrist Bones
Introduction to Hand and Wrist bone anatomy:
Bones of the Hand and Wrist:
- Eight small carpal bones (ossa carpi) support the wrist (carpus).
- They are arranged in two rows, each consisting of four bones.
- The proximal row of carpal bones is convex and two of the bones (scaphoid and lunate) articulates with the concave distal surface of the radius. This junction permits abduction and adduction (side to side) and flexion and extension (front to back) of the wrist joint.
- The concave distal row of carpal bones articulates with the five metacarpal bones (ossa metacarpi), which give support to the palm of the hand.
- Distal to the metacarpals are fourteen phalanx bones or phalanges (ossa digitorum), which support the fingers or digits of the hand.
- Each finger is supported by three phalanges, with the exception of the thumb, which is supported by two.
- The proximal row of phalanges (ossa phalanx proximalis) articulates with the metacarpals and middle row of phalanges (ossa phalanx media). The middle row of phalanges articulates with the proximal and distal rows (ossa phalanx distalis) of phalanges.
Easily and efficiently learn the bones of the body with interactive quizzes and labelling exercises.
Hand and Wrist Bone Anatomy on Palmar View:
Carpal Bones: Proximal Row
- Scaphoid bone (os scaphoideum) is a boat-shaped bone (Gr. skaphoidis, boat) located on the lateral (thumb) side of the carpus (wrist). It articulates with the distal end of the radius bone.
- Lunate bone (os lunatum) is cresent-shaped bone (L. luna, moon) located medial to the scaphoid bone. Its concave proximal surface also articulates with the distal end of the radius bone.
- Triquetral bone (os triquetrum) is a pyramid-shaped bone (L. triquetrus, triangular) located medial to the lunate bone on the ulnar side of the carpus.
- Pisiform bone (os pisiforme) is a small, pea-shaped bone that articulates with the triquetral bone on the ulnar side of the carpus (L. pisum, pea + forma, shape). It is embedded in the tendon of the flexor carpi ulnaris muscle (= sesamoid bone) and increases tension during muscle contraction.
Use these interactive quizzes and labeling exercises to quickly and efficiently learn the anatomy of the carpal bones.
Carpal Bones: Distal Row
- Trapezium bone (os trapezium) is an irregular-shaped bone located distal to the scaphoid bone on the lateral (thumb) side of the carpus (Gr, tetrapeza, object with four feet). It is the radial (lateral) border of the carpal tunnel, and its distal surface articulates with the proximal surface of the first metacarpal (thumb) bone.
- Trapezoid bone (os trapezoideum) is a small, four-sided bone that is wedged between the trapezium and capitate bones (Gr. trapezoid, a four-sided figure with two parallel sides). It articulates with the proximal end of the second metacarpal bone.
- Capitate bone (os capitatum) is located medial to the trapezium in the center of the distal row of the carpus. The name of the bone is based on its rounded proximal head (L. caput, head), which fits into the concavities of scaphoid and lunate bones. Distally, the capitate bone articulates with the proximal end of the third metacarpal bone.
- Hamate bone (os hamatum) is located on the ulnar side of the carpus. Projecting from its palmar surface is a hook-like process that forms the ulnar (medial) border of the carpal tunnel (L., hamat, hooked). The hamate bone articulates distally with the fourth and fifth metacarpal bones.
Metacarpal Bones (Metacarpus)
Metacarpal bones(ossa metacarpi) are the bones that support the palm of the hand. Each consists of a elongated body (shaft), cuboid base, and convex head. The bases articulate with the distal row of the carpus and the heads articulate with the proximal phalanges. Each bone is assigned a number from 1 to 5, starting on the lateral side (thumb side) of the hand.
The phalanges (singular: phalanx) are the fourteen bones that support the fingers or digits of the hand (ossa digitorum manus). Each finger is supported by three phalanges, exception of the thumb, which is supported by two.
- Proximal: I - V (os phalanx proximalis) are the phalanges located directly anterior to metacarpal bones. The proximal phalanges articulate anteriorly with the middle phalanges, except the first proxmial phalanx, which articulates with first distal phalanx.
- Middle: II - V (os phalanx media II – V) are the phalanges located between the proximal and distal phalanges
- Distal: I - V (os phalanx distalis I – V) are the phalanges that support the tips of the fingers. All articulate posteriorly with a middle phalanx, except the first distal phalanx, which articulates with the first proximal phalanx.