Left hand shown with thumb on left. The<unk> s form a transverse arch to which the rigid row of distal carpal bones are fixed. The peripheral<unk> s (those of the thumb and little finger) form the sides of the cup of the palmar gutter and as they are brought together they deepen this concavity. The index<unk>  is the most firmly fixed, while the thumb<unk>  articulates with the trapezium and acts independently from the others. The middle<unk> s are tightly united to the carpus by intrinsic interlocking bone elements at their bases. The ring<unk>  is somewhat more mobile while the fifth<unk>  is semi-independent. Each<unk> consists of a body or shaft, and two extremities: the head at the distal or digital end (near the fingers), and the base at the proximal or carpal end (close to the wrist). Body The body (shaft) is prismoid in form, and curved, so as to be convex in the longitudinal direction behind, concave in front. It presents three surfaces: medial, lateral, and dorsal. * The medial and lateral surfaces are concave, for the attachment of the interosseus muscles, and separated from one another by a prominent anterior ridge. * The dorsal surface presents in its distal two-thirds a smooth, triangular, flattened area which is covered in by the tendons of the extensor muscles. This surface is bounded by two lines, which commence in small tubercles situated on either side of the digital extremity, and, passing upward, converge and meet some distance above the center of the bone and form a ridge which runs along the rest of the dorsal surface to the carpal extremity. This ridge separates two sloping surfaces for the attachment of the interossei dorsales. * To the tubercles on the digital extremities are attached the collateral ligaments of the metacarpophalangeal joints. Base The base (basis) or carpal extremity is of a cuboidal form, and broader behind than in front: it articulates with the carpal bones and with the adjoining<unk> ; its dorsal and volar surfaces are rough, for the attachment of ligaments. Head The head (caput) or digital extremity presents an oblong surface markedly convex from before backward, less so transversely, and flattened from side to side; it articulates with the proximal phalanx. It is broader, and extends farther upward, on the volar than on the dorsal aspect, and is longer in the antero-posterior than in the transverse diameter. On either side of the head is a tubercle for the attachment of the collateral ligament of the metacarpophalangeal joint. The dorsal surface, broad and flat, supports the tendons of the extensor muscles. The volar surface is grooved in the middle line for the passage of the flexor tendons, and marked on either side by an articular eminence continuous with the terminal articular surface. Neck The neck, or subcapital segment, is the transition zone between the body and the head. Articulations Besides the metacarpophalangeal joints, the<unk>  articulate by carpometacarpal joints as follows: # the first with the trapezium; # the second with the trapezium, trapezoid, capitate and third<unk> ; # the third with the capitate and second and fourth<unk> s; # the fourth with the capitate, hamate, and third and fifth<unk> s; # and the fifth with the hamate and fourth<unk> ; File:Carpus.Carpometacarpal joints of the left hand. Thumb on left. File:Ospoignet.Carpometacarpal joints of the left hand. Thumb on left. File:814 Radiograph of Hand.X-ray Insertions Extensor Carpi Radialis Longus/Brevis: Both insert on the base of<unk>  II; Assist with wrist extension and radial flexion of the wrist Extensor Carpi Ulnaris: Inserts on the base of<unk>  V; Extends and fixes wrist when digits are being flexed; assists with ulnar flexion of wrist Abductor Pollicis Longus: Inserts on the trapezium and base of<unk>  I; Abducts thumb in frontal plane; extends thumb at carpometacarpal joint Opponens Pollicis: Inserts on<unk>  I; flexes<unk>  I to oppose the thumb to the fingertips Opponens digiti minimi: Inserts on the medial surface of<unk>  V; Flexes<unk>  V at carpometacarpal joint when little finger is moved into opposition with tip of thumb; deepens palm of hand. File:Gray219 - Metacarpus.Metacarpus (yellow). Insertions are shown in red. Left hand, anterior (palmar) view. File:Gray220 - Metacarpus.Metacarpus (yellow). Insertions are shown in red. Left hand, posterior (dorsal) view.
Metacarpal bones
Sawbones 
Scalpel
Ulnar claw
Sesamoid bone
Elm yellows
Earmold
Epiphyseal plate