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The extensor carpi radialis longus is a wrist extensor that is innervated by the radial nerve, [2] [3] from spinal roots C6 and C7. [4] All other major extensor muscles in the superficial layer of the posterior compartment (the extensor digitorum , extensor carpi radialis brevis , extensor carpi ulnaris , and extensor digiti minimi ) are ...
Wrist extension is achieved by muscles in the forearm contracting, pulling on tendons that attach distal to (beyond) the wrist. If the tendons, muscles, or nerves supplying these muscles are damaged or otherwise not working as they should be, wrist drop may occur. The following situations may result in wrist drop:
The ED inserts into the middle and distal phalanges to extend the fingers and wrist. Opposite the head of the second metacarpal bone, the EI joins the ulnar side of the ED tendon to extend the index finger. The EDM has a similar role for the little finger. The ECU inserts at the base of the 5th metacarpal to extend and
The median nerve innervates the flexors of the wrist and digits, the abductors and opponens of the thumb, the first and second lumbricals. The ulnar nerve innervates the remaining intrinsic muscles of the hand. [3] [4] All muscles of the hand are innervated by the brachial plexus (C5–T1) and can be classified by innervation: [1] [4] [5]
Injuries (such as by an external flexion force during active extension) may allow the tendon to dislocate into the intermetacarpal space; the extensor tendon then acts as a flexor and the finger may no longer be actively extended. This may be corrected surgically by using a slip of the extensor tendon to replace the damaged ligamentous band. [6]
It is innervated by the ulnar nerve in 50% of people and by both the median and ulnar nerves in 15%. The opponens pollicis originates on the tubercle of the trapezium and the flexor retinaculum. It is inserted onto the radial side of the first metacarpal. It opposes the thumb and assists in adduction. It is innervated by the median nerve. [6]
Loss of wrist extension is due to loss of the ability to move of the posterior compartment of forearm muscles. [3] [1] In the event of lacerations to the wrist area the symptom would therefore be sensory. Additionally, depending on the type of trauma, other nerves may be affected such as the median nerve and axillary nerves. [5]
The supinator and the anconeus are the two extensor muscles in the posterior compartment of the forearm that do not pass through wrist extensor compartments. [ 3 ] The first compartment locating the most radial is occupied by the extensor pollicis brevis and the abductor pollicis longus to insert to the thumb.