Metacarpal bones

In human anatomy, the metacarpal bones or metacarpus, form the intermediate part of the skeletal hand located between the phalanges of the fingers and the carpal bones of the wrist which forms the connection to the forearm. The metacarpal bones are analogous to the metatarsal bones in the foot.Carpometacarpal joints of the left hand. Thumb on left.Carpometacarpal joints of the left hand. Thumb on left.Metacarpus (yellow). Insertions are shown in red. Left hand, anterior (palmar) view.Metacarpus (yellow). Insertions are shown in red. Left hand, posterior (dorsal) view.Metacarpus of the left hand (shown in red). Animation.X-ray image of right hand with thumb on left.Multiple fractures of the metacarpals (aka broken hand). (Right hand shown with thumb on left.)X-ray image of human infant left hand.Micro-radiography of 8 weeks human embryo handRight hand. Deep dissection. Anterior (palmar) view.Right hand. Deep dissection. Posterior (dorsal) view. In human anatomy, the metacarpal bones or metacarpus, form the intermediate part of the skeletal hand located between the phalanges of the fingers and the carpal bones of the wrist which forms the connection to the forearm. The metacarpal bones are analogous to the metatarsal bones in the foot. The metacarpals form a transverse arch to which the rigid row of distal carpal bones are fixed. The peripheral metacarpals (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 metacarpal is the most firmly fixed, while the thumb metacarpal articulates with the trapezium and acts independently from the others. The middle metacarpals are tightly united to the carpus by intrinsic interlocking bone elements at their bases. The ring metacarpal is somewhat more mobile while the fifth metacarpal is semi-independent. Each metacarpal bone 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). 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 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 metacarpal bones; its dorsal and volar surfaces are rough, for the attachment of ligaments. 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. The neck, or subcapital segment, is the transition zone between the body and the head.