Compartments Deep to the Extensor Retinaculum

The extensor retinaculum of the wrist serves as a fibrous band that holds the extensor tendons in place, preventing bowstringing during movement. Beneath this structure lie six distinct tendon compartments, each housing specific muscles responsible for wrist and finger extension.

Individual Tendon Compartments and Their Associated Muscles

First Compartment

• Abductor pollicis longus
• Extensor pollicis brevis

Responsible for thumb abduction and extension.

Second Compartment

• Extensor carpi radialis longus
• Extensor carpi radialis brevis

Facilitates wrist extension and radial deviation.

Third Compartment

• Extensor pollicis longus

Enables thumb extension.

Fourth Compartment

• Extensor digitorum
• Extensor indicis

Controls finger extension.

Fifth Compartment

• Extensor digiti minimi

Dedicated to the extension of the little finger.

Sixth Compartment

• Extensor carpi ulnaris

Supports wrist extension and ulnar deviation.

Understanding the anatomical layout of these compartments is essential for diagnosing and treating extensor tendon pathologies effectively.