anatomyfingers

Anatomy of the fingers refers to the digits of the hand, typically excluding the thumb in common usage; a hand contains a thumb (pollex) and four fingers: index, middle, ring, and little finger. The structure of the fingers combines bones, joints, tendons, muscles, nerves, and vessels that enable a wide range of precise movements and grips.

Bones and joints: Each finger has three phalanges—proximal, middle, and distal—except the thumb, which has two. The fingers articulate with the metacarpal bones at the metacarpophalangeal joints (knuckles) and with adjacent phalanges at the proximal and distal interphalangeal joints. The thumb has an interphalangeal joint. The metacarpals connect to the wrist bones, forming the palm.

Tendons, muscles, and soft tissue: Flexion of the fingers is produced by the flexor digitorum superficialis (to the middle phalanx) and flexor digitorum profundus (to the distal phalanx). Extension is mainly by the extensor digitorum, with additional support from the extensor mechanism and the intrinsic hand muscles, including the interossei and lumbricals, which help coordinate motion at the metacarpophalangeal and interphalangeal joints. The palmar and dorsal ligaments, along with the extensor expansions, stabilize the fingers during movement.

Nerves and blood supply: Sensation on the palmar and lateral aspects of the fingertips is provided mainly by the median nerve (for the lateral three and a half digits) and the ulnar nerve (for the medial one and a half digits); digital nerves branch from these nerves. Blood supply to the fingers comes from digital arteries derived from the superficial and deep palmar arches.

Function and clinical notes: The fingers enable both precision manipulation and power grip through coordinated flexion, extension, abduction, and adduction. Common injuries include mallet finger (extensor tendon avulsion) and jersey finger (flexor digitorum profundus avulsion), with other conditions such as Dupuytren’s contracture impacting finger motion.