Collateral Ligaments of the Metacarpophalangeal Joints, Posterior View

Description

Seen from the posterior (dorsal) aspect of an adult male hand, the metacarpophalangeal (MCP) articulations are framed by the heads of the metacarpals proximally and the bases of the proximal phalanges distally, with the joint capsule spanning between them. Collateral ligaments arise from the dorsolateral tubercles of each metacarpal head and course distally and slightly volarly to insert on the tubercles at the base of the proximal phalanx, sitting lateral and medial to each MCP joint line. Between adjacent metacarpals, the deep transverse metacarpal ligaments form a transverse band at the level of the metacarpal heads, tethering the volar plates and limiting excessive splay. Clean landmarks. Functionally, this posterior perspective clarifies why MCP stability changes with finger position: the collateral ligaments tighten in flexion and slacken in extension because of the cam-shaped metacarpal head, a key teaching point when explaining why abduction and adduction are freer with the fingers extended. That mechanical detail matters in common injuries such as thumb ulnar collateral ligament tears (skier’s thumb), where valgus stress at the first MCP can destabilize pinch, and in “boxer’s knuckle,” where sagittal band disruption at the dorsal MCP alters extensor tendon tracking but the collateral ligaments still define the joint’s lateral boundaries. The relationship to the synovial capsule also helps when discussing capsular thickening and contracture after trauma or inflammatory arthropathy. Hand anatomy curricula, orthopaedic and plastic surgery teaching files, and sports medicine patient education materials frequently need a clear depiction of MCP collateral ligament orientation relative to the metacarpal heads and proximal phalanges. Publishers can also pair this view with radiographs or MRI to annotate coronal-plane stress views and ligament insertion sites at the tubercles. Anatomical accuracy verified by SciePro's Medical Advisory Board.