Extensor carpi radialis longus: Difference between revisions
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== Description == | == Description == | ||
Extensor carpi radialis longus lies on the lateral side of the posterior compartment of the forearm, being partly covered by brachioradialis. Approximately in the middle of the forearm, the muscle forms a flattened tendon which runs distally over the lateral surface of the radius. In the lower third of the forearm, the tendon, together with that of extensor carpi radialis brevis, is crossed by the tendons of abductor pollicis longus and extensor pollicis brevis. The tendons of extensor carpi radialis longus and brevis pass deep to the extensor retinaculum in a common synovial sheath. Together they groove the posterior surface of the styloid process of the radius. | Extensor carpi radialis longus lies on the lateral side of the posterior compartment of the forearm, being partly covered by brachioradialis. Approximately in the middle of the forearm, the muscle forms a flattened tendon which runs distally over the lateral surface of the radius. In the lower third of the forearm, the tendon, together with that of extensor carpi radialis brevis, is crossed by the tendons of abductor pollicis longus and extensor pollicis brevis. The tendons of extensor carpi radialis longus and brevis pass deep to the extensor retinaculum in a common synovial sheath. Together they groove the posterior surface of the styloid process of the radius.<ref name=":0">Palastanga N, Field D, Soames R. Anatomy and human movement: structure and function. 5th ed. Edinburgh: Butterworth Heinemann/Elsevier; 2006.</ref> | ||
=== Origin === | === Origin === | ||
Extensor carpi radialis longus arises from the anterior part of the lower third of the lateral supracondylar ridge of the humerus and adjacent intermuscular septum. Occasionally, there may be an attachment to the lateral epicondyle by the common extensor tendon. | Extensor carpi radialis longus arises from the anterior part of the lower third of the lateral supracondylar ridge of the humerus and adjacent intermuscular septum. Occasionally, there may be an attachment to the lateral epicondyle by the common extensor tendon.<ref name=":0" /> | ||
=== Insertion === | === Insertion === | ||
The tendon of the extensor carpi radialis longus attaches to the posterior surface of the base of the second metacarpal. | The tendon of the extensor carpi radialis longus attaches to the posterior surface of the base of the second metacarpal.<ref name=":0" /> | ||
=== Nerve === | === Nerve === | ||
Extensor carpi radialis longus is supplied by the radial nerve (root value C6 and 7) from the posterior cord of the brachial plexus, which enters the muscle above the elbow. The skin over the muscle is supplied by roots C5 and C6. | Extensor carpi radialis longus is supplied by the radial nerve (root value C6 and 7) from the posterior cord of the brachial plexus, which enters the muscle above the elbow. The skin over the muscle is supplied by roots C5 and C6.<ref name=":0" /> | ||
=== Artery === | === Artery === | ||
Radial artery | Radial artery<ref name=":0" /> | ||
== Function == | == Function == | ||
Working with extensor carpi ulnaris, extensors carpi radialis longus and brevis produce extension of the wrist. Working with the flexor carpi radialis, however, they will produce abduction (radial deviation) of the wrist. In addition extensor carpi radialis longus may help to flex the elbow joint. | Working with extensor carpi ulnaris, extensors carpi radialis longus and brevis produce extension of the wrist. Working with the flexor carpi radialis, however, they will produce abduction (radial deviation) of the wrist. In addition extensor carpi radialis longus may help to flex the elbow joint.<ref name=":0" /> | ||
== Clinical relevance == | == Clinical relevance == | ||
Extensor carpi radialis longus is one of the three primary wrist extensors. Extensor carpi radialis longus is most effective as a wrist extensor when the elbow is extended and when radial deviation is balanced by the primary ulnar deviator- extensor carpi ulnaris. Functionally, the wrist extensors work strongly in the action of gripping, where they have a synergistic role. The synergy of the two radial extensors and extensor carpi ulnaris is an important factor in the gripping action. By maintaining the wrist in an extended position, flexion of the wrist under the action of flexors digitorum superficialis and profundus is prevented, with the result that these muscles act on the fingers. If the wrist is then allowed to flex the flexor tendons cannot shorten sufficiently to produce effective movement at the interphalangeal joints. This therefore becomes a state of active insufficiency. | Extensor carpi radialis longus is one of the three primary wrist extensors. Extensor carpi radialis longus is most effective as a wrist extensor when the elbow is extended and when radial deviation is balanced by the primary ulnar deviator- extensor carpi ulnaris. Functionally, the wrist extensors work strongly in the action of gripping, where they have a synergistic role. The synergy of the two radial extensors and extensor carpi ulnaris is an important factor in the gripping action. By maintaining the wrist in an extended position, flexion of the wrist under the action of flexors digitorum superficialis and profundus is prevented, with the result that these muscles act on the fingers. If the wrist is then allowed to flex the flexor tendons cannot shorten sufficiently to produce effective movement at the interphalangeal joints. This therefore becomes a state of active insufficiency. | ||
If the radial nerve is damaged a person is unable to produce an effective grip because of the paralysis of the wrist extensors. However, with the wrist splinted in extension, the tendons of flexors digitorum superficialis and profundus act on the fingers and a functional grip can be obtained. | If the radial nerve is damaged a person is unable to produce an effective grip because of the paralysis of the wrist extensors. However, with the wrist splinted in extension, the tendons of flexors digitorum superficialis and profundus act on the fingers and a functional grip can be obtained.<ref name=":0" /> | ||
== Assessment == | == Assessment == | ||
Revision as of 20:38, 25 June 2018
Original Editor - Wanda van Niekerk
Top Contributors - Wanda van Niekerk, Nina Myburg, Kim Jackson, Aya Alhindi, Rachael Lowe and Amanda Ager
Description[edit | edit source]
Extensor carpi radialis longus lies on the lateral side of the posterior compartment of the forearm, being partly covered by brachioradialis. Approximately in the middle of the forearm, the muscle forms a flattened tendon which runs distally over the lateral surface of the radius. In the lower third of the forearm, the tendon, together with that of extensor carpi radialis brevis, is crossed by the tendons of abductor pollicis longus and extensor pollicis brevis. The tendons of extensor carpi radialis longus and brevis pass deep to the extensor retinaculum in a common synovial sheath. Together they groove the posterior surface of the styloid process of the radius.[1]
Origin[edit | edit source]
Extensor carpi radialis longus arises from the anterior part of the lower third of the lateral supracondylar ridge of the humerus and adjacent intermuscular septum. Occasionally, there may be an attachment to the lateral epicondyle by the common extensor tendon.[1]
Insertion[edit | edit source]
The tendon of the extensor carpi radialis longus attaches to the posterior surface of the base of the second metacarpal.[1]
Nerve[edit | edit source]
Extensor carpi radialis longus is supplied by the radial nerve (root value C6 and 7) from the posterior cord of the brachial plexus, which enters the muscle above the elbow. The skin over the muscle is supplied by roots C5 and C6.[1]
Artery[edit | edit source]
Radial artery[1]
Function[edit | edit source]
Working with extensor carpi ulnaris, extensors carpi radialis longus and brevis produce extension of the wrist. Working with the flexor carpi radialis, however, they will produce abduction (radial deviation) of the wrist. In addition extensor carpi radialis longus may help to flex the elbow joint.[1]
Clinical relevance[edit | edit source]
Extensor carpi radialis longus is one of the three primary wrist extensors. Extensor carpi radialis longus is most effective as a wrist extensor when the elbow is extended and when radial deviation is balanced by the primary ulnar deviator- extensor carpi ulnaris. Functionally, the wrist extensors work strongly in the action of gripping, where they have a synergistic role. The synergy of the two radial extensors and extensor carpi ulnaris is an important factor in the gripping action. By maintaining the wrist in an extended position, flexion of the wrist under the action of flexors digitorum superficialis and profundus is prevented, with the result that these muscles act on the fingers. If the wrist is then allowed to flex the flexor tendons cannot shorten sufficiently to produce effective movement at the interphalangeal joints. This therefore becomes a state of active insufficiency.
If the radial nerve is damaged a person is unable to produce an effective grip because of the paralysis of the wrist extensors. However, with the wrist splinted in extension, the tendons of flexors digitorum superficialis and profundus act on the fingers and a functional grip can be obtained.[1]
