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Lateral Band Tendons (Extensor Hood)

tendines bandae laterales

The lateral bands are the intrinsic contribution to the extensor mechanism, running dorsolateral to the PIP joint before reuniting to form the terminal tendon inserting on the distal phalanx. The triangular ligament dorsal to the PIP joint holds the lateral bands dorsal in extension. If the central slip is disrupted, the lateral bands migrate volar to the PIP axis — the boutonnière deformity mechanism.

Region: Hand & Wrist

Biomechanics

Function & Actions

PIP and DIP joint extension through the intrinsic plus pathway; PIP stabilisation against the central slip

Clinical Relevance

Clinical Notes

Boutonnière deformity from central slip disruption allows the PIP joint to buttonhole through the extensor hood while the lateral bands migrate palmarly, creating a PIP flexion and DIP hyperextension deformity. Acute treatment requires PIP extension splinting for 6 weeks to allow central slip healing. Chronic deformity requires central slip reconstruction and lateral band repositioning.

Pathology

Common Injuries & Conditions

Boutonnière Deformity

Central slip disruption causing lateral band volar migration producing PIP flexion and DIP hyperextension managed with PIP extension splinting or central slip reconstruction.