Mobile wad

Mobile wad
Posterior surface of the forearm. Superficial muscles. (Muscles of mobile wad visible at center left.)
Cross-section through the middle of the forearm. (Muscles of mobile wad visible at center left.)
Origin
Insertion
Artery	radial artery
Nerve	muscular branches of the radial nerve
Actions

The mobile wad (or mobile wad of Henry) is a group of the following three muscles found in the posterior compartment of the forearm:^[1]

• brachioradialis
• extensor carpi radialis brevis
• extensor carpi radialis longus

It is also sometimes known as the "lateral compartment"^[2] or "radial group"^[3] of the forearm.

Function

These three muscles act as flexors at the elbow joint.^[4]

The extensor carpi radialis brevis and longus are both weak flexors at the elbow joint. Brevis moves the arm from ulnar abduction to its mid-position and flexes dorsally. Longus is a weak pronator in the flexed arm and a supinator in the outstretched arm. At the carpal joints longus acts in dorsiflexion with the extensor carpi ulnaris and in radial abduction with the flexor carpi radialis. These two muscles are called "fist clenchers" because they must be slightly flexed dorsally during clenching to permit maximal flexion.

Brachoradialis is inserted distally on the radius end therefore, unlike the previous two muscles, only acts on the forearm. It brings the forearm into midposition between supination and pronation, and in this position it acts as a flexor. In slow movements and in the supinated forearm it has a minimal flexor action.

^[3]

Notes

1. ^ Baek 2004, pp 508–9
2. ^ DuParc 2003, 55–030–A-10
3. ^ ^{a b} Platzer 2004, p 164
4. ^ Note: The extensor carpi muscles are so named because they extend at the carpus, not at the elbow.

References

• Baek, GH; Kim, JS; Chung, MS (2004). "Isolated ischemic contracture of the mobile wad: a report of two cases". J Hand Surg [ Br] 29 (5): 508–9. doi:10.1016/j.jhsb.2004.06.007. PMID 15336759. 
• DuParc, Jacques (2003). Surgical Techniques in Orthopaedics and Traumatology. Elsevier Health Sciences. pp. 55–030–A–10. ISBN 2-84299-414-0. 
• Platzer, Werner (2004). Color Atlas of Human Anatomy, Vol. 1: Locomotor System (5th ed.). Thieme. ISBN 3-13-533305-1. 

External links

• Description at orthopaediccare.net
• Picture at med.tufts.edu