Forearm Extensors
What are the deep forearm extensors?
1. Abductor pollicis longus 2. Extensor pollicis longus 3. Extensor pollicis brevis 4. Extensor indicis
What muscles make up the mobile wad of three?
1. Extensor carpi radialis longus 2. Extensor carpi radialis brevis 3. Brachioradialis
What are the superficial forearm extensors?
1. Extensor carpi radialis longus & brevis 2. Extensor digitorum 3. Extensor digiti minimi 4. Extensor carpi ulnaris
What is the anatomical snuffbox?
A triangular hollow on the thenar aspect of dorsum of hand. Prominent with thumb extension.
Where is the mobile wad of three?
It is located on the lateral forearm; radial compartment.
Extensor Carpi Ulnaris
O: CET from lateral epicondyle I: Base of 5th metacarpal bone, ulnar side A: Extends & adducts wrist Innervation: Radial nerve (C6-C8)
Extensor Digiti Minimi
O: CET from lateral epicondyle I: Into extensor expansion of 5th finger with extensor digitorum tendon. A: Extends MCP & IP joints of little finger. Assists in abduction of 5th digit. Innervation: Post. interosseous n. of deep branch of radial nerve (C7, C8)
Extensor Carpi Radialis Brevis
O: CET from lateral epicondyle of humerus, elbow LCL I: Dorsal surface of base of 3rd MC bone A: Extension & assists abduction of wrist Innervation: Radial nerve (C6, C7)
Extensor Digitorum
O: CET from lateral epicondyle. I: By 4 tendons into base of middle phalanx; base of distal phalanx A: Extends MCP joints & IP joints of 2nd-5th digits. Assists in abduction of 2-4 digits; assists extension & abduction of wrist. Innervation: Deep branch of radial n. (C6, C8)
Extensor Carpi Radialis Longus
O: Distal 1/3 of lateral supracondylar ridge; lateral inter muscular septum. I: Dorsal surface of base of 2nd MC, radial side. A: Extends & abducts the wrist; assists elbow flexion Innervation: Radial nerve (C6, C7)
Extensor pollicis longus
O: Middle 1/3 of post. surface of ulna distal to origin of abductor pollicis longus, IOM I: Base of distal phalanx of thumb, dorsal surface A: Extends the IP jt. & assists extension of MCP & CMC jt. of thumb. Assists in abduction & extension of wrist. Innervation: Post. interosseous n. of deep branch of radial nerve (C7, C8)
Extensor pollicis brevis
O: Post. surface of body of radius distal to origin of abd. pollicis longus, IOM. I: Base of prox. phalanx of dorsum of thumb A: Extends MCP of the thumb, extends & abducts CMC jt. Also radially deviates wrist. Innervation: Post. interosseous n. of deep branch of radial nerve (C7, C8)
Abductor pollicis longus
O: Post. surface of body of ulna distal to origin of supinator; IOM, post. surface middle 1/3 body of radius. I: Base of 1st MC bone, radial side A: Abduction & extension of CMC joint of thumb; abduction and flexion of wrist. Innervation: Post. interosseous n. of deep branch of radial nerve (C7, C8)
Extensor Indicis
O: Post. surface of ulna body distal to origin of extensor pollicis longus. I: Into extensor expansion of index finger with extensor digitorum longus tendon. A: Extension of MCP & IP joints of index finger. may assist in adduction of index finger. Innervation: Post. interosseous n. of deep branch of radial nerve (C7, C8)
What are the borders of the anatomical snuffbox?
Radially - APL Medially - EPB Posteromedial - EPL Floor - Radial styloid process; scaphoid; trapezium & base of 1 MC.
What is found in the mobile wad of three?
The radial nerve and artery lie between the mobile wad of three (radial compartment) and the deep & superficial flexor compartment.
