Extensor mechanism of finger

EXTENSOR MECHANISM OF
FINGER
LIKI PEDIA

Structures involved
 Extensor digitorum communis
 Extensor indicis proprius
 Extensor digiti minimi

 These muscles passes from the forearm to
hand beneath extensor retinaculum.
 The tendons of EDC, EIP & EDM variability on
the dorsum of hand.
 EDC tendon leads to the extensor hood.
 1EIP tendon insert into the hood of EDC.
 EDC tendon of one finger may also be
connected to adjacent finger by juncturae
tendinae.

 EDC tendon of each finger is split into 3 bands
 1. Central tendon
 2. Lateral band
 3.Terminal band

1. Central band
 Inserts at the base of middle phalanx.

2. Lateral band and 3.
Terminal band
 Both the lateral band rejoins to form the
terminal band at the distal phalanx.

 EDC have two components
 Active components
 Passive components

Active components
 Dorsal interossei
 Volar interossei
 Lumbricals

 Proximal – dorsal and volar interossei arises
from the sides of metacarpal joints
 Distal – join at the extensor hood which also
wraps the EDC and also contributes the
central tendon and lateral band fibers.
 Lumbricals and interossei both together refer
to as intrinsic muscles.

Passive components
 Sagittal band
 Oblique retinacular ligament
 Triangular ligament

Sagittal band
 It helps in stabilization of lateral bands on the
dorsum of hand.
 It connects the dorsal surface of extensor
hood to the volar plate and the deep
transverse metacarpal ligament.
 Sagittal band is not only for volar plates but
also it stabilizes the hood of MCP joint.
 It prevents the bowstring of extensor
mechanism.

Oblique retinacular ligament
 Proximal – both the side of proximal phalanx
and annular and cruciate pulleys.
 Distal – distal to the distal phalangeal joint.

Triangular ligament
 Triangular ligament & sagittal bands are
interconnected by the lateral band

Extensor mechanism of finger

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