Separate the extensor carpi ulnaris, extensor digiti minimi and extensor digitorum muscles from the underlying structures. Elevate these muscles to reveal the extensor indicis, extensor pollicis longus, extensor pollicis brevis and abductor pollicis longus muscles. (G 2.84;N 431;Gl 26.19B)
- Identify the extensor indicis muscle and tendon.
- Identify the extensor pollicis longus muscle and tendon. Trace the tendon around the dorsal tubercle of the radius to its distal attachment to the base of the distal phalanx of the thumb.
- Identify the extensor pollicis brevis muscle and tendon. Trace the tendon to its distal attachment to the base of the proximal phalanx of the thumb.
- Identify the abductor pollicis longus muscle and tendon. Trace the tendon to its distal attachment on the base of the 1st metacarpal and trapezium.
- Identify the radial artery passing deep to the tendons of the abductor pollicis longus, extensor pollicis brevis and extensor pollicis longus muscles.
Important Relationships
- The tendon of the abductor pollicis longus muscle is positioned lateral to the tendon of the extensor pollicis brevis.
- The tendon of the extensor pollicis longus muscle passes directly posterior (superficial) to the tendon of the extensor carpi radialis longus.
- The tendon of the extensor pollicis longus muscle passes directly posterior (superficial) to the tendon of the extensor carpi radialis brevis.
- The tendon of the extensor pollicis longus muscle is positioned medial to the tendon of the extensor pollicis brevis.
- The radial artery passes deep to the tendons of the abductor pollicis longus, and extensor pollicis longus and brevis muscles.
- The radial artery passes directly posterior to the trapezium and base of the first metacarpal.
