The metatarsal bones, five in number, are situated in the anterior part of the foot in front of the tarsals and behind the phalanges. They are enumerated from the medial to the lateral side.
THE COMMON CHARACTERISTICS OF THE METATARSAL BONES
Like the metacarpals the metatarsals are miniature long bones, and each possesses a shaft, a base or proximal end, and a head or distal end.
With the exception of the first and, to a lesser degree, the fifth, the shafts are long and slender, and are slightly convex longitudinally on their dorsal aspects and concave on their plantar aspects. They are prismoid in form and taper from the base to the head.
The bases articulate with the distal row of the tarsals and with one another. The line of each tarsometatarsal joint, excluding the first, passes backwards and laterally, and the bases of the metatarsals are therefore set somewhat obliquely relative to their shafts, a fact which assists in the recognition of the side of the body to which the bones belong.
The heads articulate with the proximal phalanges of their own digits, each by means of a convex articular surface, which extends further on the plantar than on the dorsal surface ; the plantar extension ends on each side on the summit of a slight articular eminence. The sides of the heads are flattened and each shows a depression surmounted dorsally by a tubercle, which gives attachment to one of the collateral ligaments of the metatarsophalangeal joint.
THE CHARACTERISTICS OF THE INDIVIDUAL METATARSAL BONES
The first metatarsal bone (fig. 495) is the shortest and thickest of the metatarsal bones. The body is strong, and of well-marked prismoid form. The base has no articular facets on its sides, but there is occasionally a pressure facet on the lateral side caused by contact with the second metatarsal bone. Its proximal articular surface, of large size and kidney-shaped, articulates with the first cuneiform bone; the lateral border of the facet shows a slight indentation, which represents the hilum of the kidney. Its circumference is grooved for the tarsometatarsal ligaments, and medially gives insertion to a part of the tendon of the tibialis anterior; its plantar angle presents a rough, oval prominence for the insertion of the tendon of the peroneus longus. The lateral surface of the shaft is flat and gives origin to the medial head of the first dorsal interosseous muscle. The head is large; on its plantar surface there is a median elevation separating two grooved facets, on which sesamoid bones glide.
The fifth metatarsal bone (fig. 499) is recognized by a rough eminence, termed the tubercle. on the lateral side of its base. The base articulates proximally by a triangular, oblique surface with the cuboid bone, and medially, with the. fourth metatarsal bone.
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