- Anatomy
- Features
- Lateral epicondylitis
- - What is it?
- - Pathophysiology
- - Treatment
- Non-surgical treatment
- Surgical treatment
- References
The extensor carpi radialis brevis is a muscle located in the forearm that has the main function of extending and abducting the hand. It is part of a group of seven superficial extensor muscles found in the forearm. Four of these seven muscles have the same origin, in the lower portion of the humerus.
This muscle shares the same synovial sheath with the extensor carpi radialis longus. The synovial sheath is a fluid-forming structure that lines the tendons and cushions their movement against the bones.
By Henry Vandyke Carter - Henry Gray (1918) Anatomy of the Human Body (See «Book» section below) Bartleby.com: Gray's Anatomy, Plate 418, Public Domain, https://commons.wikimedia.org/w/index. php? curid = 27292
The injury to your tendon, called lateral epicondylitis or popularly as tennis elbow, is one of the main reasons for consultation in trauma, since it causes a lot of pain and inflammation in the outer part of the elbow.
Anatomy
The elbow is a joint that joins the arm with the forearm and allows the mobility of the upper limb.
It is made up of three bones, the humerus in the upper part, and the radius and ulna in the lower part; This is why it is also known as the humerus-radio-ulnar joint.
From Anonymous - Own work, CC BY-SA 3.0, In the proximal elbow, the humerus has two protrusions called the medial and lateral epicondyles. Several of the muscles that handle flexion and extension movements of the wrist are inserted into these protrusions.
The extensor carpi radialis brevis originates from the lateral epicondyle. It shares this insertion site with three other extensor muscles: the extensor carpi ulnaris, the extensor digiti minimi, and the extensor digitorum.
From Henry Vandyke Carter - Henry Gray (1918) Anatomy of the Human Body (See "Book" section below) Bartleby.com: Gray's Anatomy, Plate 330, Public Domain, https://commons.wikimedia.org/w/index. php? curid = 1600204
Together with these muscles, it is part of the seven superficial extensor muscles of the forearm.
Completing the group of extensor muscles are the brachioradialis muscle, the extensor carpi radialis longus, and the anconeus, which do not share the insertion point of the extensor carpi radialis brevis, but do share their functions.
In its journey, it accompanies the extensor carpi radialis longus, being partially covered by it and complementing its functions.
Both muscles share the same synovial sheath, which is a fluid-forming fibrous sheet that protects the tendons from continuous friction against the bone surface.
De Me - I created this from Gray's Anatomy plate 418 using Gimp, Public Domain, The distal insertion of the extensor carpi radialis brevis is lateral to the third metacarpal bone.
Regarding the blood supply, this muscle receives its supply directly from the radial artery and, indirectly, from some of its collateral branches, mainly from the radial recurrent artery.
By Henry Vandyke Carter - Henry Gray (1918) Anatomy of the Human Body (See «Book» section below) Bartleby.com: Gray's Anatomy, Plate 528, Public Domain, https://commons.wikimedia.org/w/index. php? curid = 541389
For its part, the neurological supply is ensured by direct branches of the radial nerve, which runs lateral to it.
Features
The extensor carpi radialis brevis is primarily concerned with the extension and adduction movements of the wrist joint.
The extension of the wrist can reach an amplitude of up to approximately 85 °. For its part, the adduction of the wrist is the movement of the hand in the direction of the first finger or thumb.
The adduction movement can reach up to 55 °, when done forcibly.
By Yahia.Mokhtar - Own work, CC BY-SA 4.0, Both extension and adduction movements are carried out by the extensor carpi radialis brevis, supported by the extensor carpi radialis longus.
Lateral epicondylitis
- What is it?
Inflammation of the extensor carpi radialis brevis insertion tendon is known as lateral epicondylitis. It is the most common inflammatory pathology of the elbow.
Despite being colloquially called tennis elbow, only 5% of patients with this condition are practitioners of that sport. Lateral epicondylitis can be found in anyone who performs activities that strain the elbow joint, especially with continuous flexion and extension movements.
By BruceBlaus - Own work, CC BY-SA 4.0, It can be observed both in tennis players and in other types of athletes such as baseball players, javelin throwers, golfers, among others.
It can also be due to bone degeneration due to age or the overuse of the joint due to the work that is done. Masons, typists, and mechanics are some of the workers who are exposed to this injury.
- Pathophysiology
The process by which chronic inflammation forms in the tendon of the extensor carpi brevis is a mechanism that has been studied in detail, given the high rate of consultations for this condition.
Due to overload due to overuse of the wrist joint, especially in extension and flexion movements, the extensor carpi brevis tendon begins to have minimal tears.
By www.scientificaimations.com - https://commons.wikimedia.org/wiki/File:Tennis-Elbow_SAG.jpg, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid = 56631800
These small lesions are triggering the inflammatory process. When there is no rest and there is no rest for the joint, inflammation causes fibrous tissue to form with few blood vessels, similar to scar tissue.
All of this prevents there from being a true remodeling and complete healing of the tendon, whereby severe pain and chronic inflammation begins.
Once the clinical picture is fully installed, symptoms do not improve unless treatment is administered.
- Treatment
Most lateral epicondylitis, in its initial stages, improve with clinical therapy, without the need for invasive techniques. However, in some cases, surgery is the only treatment that gives a definitive cure.
Non-surgical treatment
Non-invasive treatment consists of the administration of topical analgesics, rest, partial immobilization with a sling, rehabilitation with special physical therapy exercises, thermal radiofrequency, and shock wave therapy.
If the patient does not improve or the symptoms increase after three weeks of non-invasive treatment, a second phase must be passed, which is non-surgical invasive treatment.
This stage consists of injections for steroid infiltration at the tendon insertion site, to improve inflammation.
By Σχέδιο: Δρ. Χαράλαμπος Γκούβας (Harrygouvas) - Own work by the original uploader, CC BY-SA 3.0, Botulinum toxin injection is another treatment used to prevent continued tendon damage. This toxin is a neurotoxin that works by causing temporary paralysis of the muscles.
Biological therapies, with infiltration of platelet-rich plasma or the patient's own whole blood, are being widely used today, showing a significant improvement in the pathology.
Surgical treatment
This type of treatment is reserved for those cases in which conservative therapies have been tried without observing any type of improvement.
The goal of surgery is to remove the fibrous scar tissue that has formed at the tendon insertion point, to promote its improvement with new healthy tissue.
The results of the surgery are very good in the long term and the patient can return to their activities around four weeks after the procedure.
References
- Walkowski, AD; Goldman, EM. (2019). Anatomy, Shoulder and Upper Limb, Forearm Extensor Carpi Radialis Brevis Muscle. StatPearls. Taken from: ncbi.nlm.nih.gov
- Álvarez Reya, G; Álvarez Reyb, I; Álvarez Bustos, G. (2006). Tennis elbow (external epicondylar tendinosis): ultrasound-guided sclerosing treatment with polidocanol. About two cases. Apunts. Sports medicine. Taken from: apunts.org
- Lai, W. C; Erickson, B. J; Mlynarek, R. A; Wang, D. (2018). Chronic lateral epicondylitis: challenges and solutions. Open access journal of sports medicine. Taken from: ncbi.nlm.nih.gov
- Cowboy-Picado, A; Barco, R; Antuña, SA (2017). Lateral epicondylitis of the elbow. EFORT open reviews. Taken from: ncbi.nlm.nih.gov
- Buchanan BK, Varacallo M. (2019). Tennis Elbow (Lateral Epicondylitis). StatPearls. Taken from: ncbi.nlm.nih.gov