In anatomy, phalanx bones (plural phalanges) are bones that form the skeleton of the toes and the fingers. Proximal phalanges are closest to the main part of the foot and articulate with the metatarsals of the foot. Middle or intermediate phalanges are between the distal and proximal. The thumb and big toe do not have middle phalanges. They have concave proximal ends and convex distal ends with very shortened, constricted shafts. Articulations The middle phalanges articulate with the proximal and distal phalanges. The articulation between the proximal phalanges and middle phalanges in the four smaller fingers and toes is known as the proximal interphalangeal joint. The articulation between the middle phalanges and distal phalanges is known as the distal interphalangeal joint.