Each bone is long with a proximal quadrilateral base, a shaft (body) and a distal rounded head. The bones are numbered laterally, from the thumb, 1 – 5. The metacarpus, the palm of the hand, which is made up of five bones – the metacarpals. The long flexor tendons of the digits and thumb and the median nerve pass through the carpal tunnel The Metacarpus The Carpal Tunnel – formed by the anterior concave space formed by the pisiform and hamate – on the ulnar side and the scaphoid and trapezium – on the radial side, with a roof-like covering of the flexor retinaculum (strong fibrous bands of connective tissue). Straight Line To Pinky, Here Comes The Thumb.The following pneumonic makes it easy to remember the position of each bone, naming the carpal bones in a circle, starting with the proximal row from the scaphoid towards the pinky (small finger) and then the distal row starting from the hamate towards the thumb: Hamate – hooked – This is wedge shaped with a curved palpable hook projecting from the palmar surface near the base of the fifth metacarpal.The distal surface articulates mainly with the base of the third metacarpal but also by narrow surfaces with the bases of the second and fourth metacarpals. Capitate - head shaped – The largest of all the carpal bones sitting centrally and articulating with the lunate and scaphoid, medially with the hamate and laterally with the trapezoid.Trapezoid – four sided figure with two parallel sides – Articulates distally with the second metacarpal, laterally with the trapezium, proximally with the scaphoid and medially with the capitate.Its articular surface is saddle-shaped and contributes to the mobility of the carpometacarpal joint of the thumb Trapezium – four sided figures with no two sides parallel – the most irregular, with a palpable tubercle and groove anterior medially. It articulates proximally with the scaphoid and medially with the trapezoid.The anterior surface projects distally and laterally forming the medial part of the carpal tunnel. It articulates with the palmar surface of the triquetrum. Pisiform – (pea shaped) = a small round bone found in the tendon of flexor carpi ulnaris.When the hand is adducted it enters the radiocarpal joint. Triquetrum – (three cornered) – Nestles in the space between the lunate and hamate.Proximally it articulates with the radius and articular disc, medially with the triquetrum, laterally with the scaphoid and distally with the head of the capitate Lunate – (moon shaped) – Its palmar surface is smooth and convex and is larger than its dorsal surface.It is a common site of fracture- 70% of all carpal fractures, often injured by a fall onto an outstretched limb Articulates proximally with radius, medially with lunate and distally with the head of the capitate. Scaphoid – (boat like)– anterior surface palpable tubercle.The exception to this is the capitate which has a larger range of movement. The arrangement of the bones and ligaments allows very little movement between bones, but they do slide contributing to the finer movements of the wrist. The joints formed between the carpal bones are known as the intercarpal joints and most are of the plane synovial type, as the bones interlock with each other the rows are sometimes referred to as two single synovial joints.The four carpal bones in the distal row articulate with the bases of the five metacarpal bones forming the carpometacarpal joints.Three of the bones in the proximal row articulate with the radius forming the radiocarpal joint and distally with the distal carpal forming the midcarpal joint.The carpus controls length-tension relationships in the multiarticular hand muscles and to allow fine adjustment of grip.Image: Overview of the bones of the wrist and hand The Carpus The distal region the phalanges (fingers).The middle region the metacarpus (palm).Proximal region of the hand is the carpus (wrist).Each finger has three phalanges (the distal, middle, and proximal) the thumb has two. the phalanges (singular phalanx) – the 14 narrow bones that make up the fingers of each hand.the metacarpals – the five bones that comprise the middle part of the hand.the hamate, capitate, trapezoid and trapezium on the lower side of the hand.the pisiform, triquetrum, lunate and scaphoid on the upper end of the wrist.The carpal bones are bound in two groups of four bones: The carpus is formed from eight small bones collectively referred to as the carpal bones. The hand and wrist have a total of 27 bones arranged to roll, spin and slide allowing the hand to explore and control the environment and objects.

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