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Palmaris longus muscle
Template:Muscle infobox The palmaris longus is seen as a small tendon between the flexor carpi radialis and the flexor carpi ulnaris, although it is not always present. The muscle is absent in about 14 percent of the population, however this varies greatly with ethnicity. Absence of palmaris does not have any known effect on grip strength. However, lack of said muscle is disadvantageous in that its tendon can not be harvested as a graft if necessary.
Palmaris longus can be palpated by touching the pads of the fifth and first fingers and flexing the wrist. The tendon, if present, will be very visible.
It ends in a slender, flattened tendon, which passes over the upper part of the flexor retinaculum, and is inserted into the central part of the flexor retinaculum and lower part of the palmar aponeurosis, frequently sending a tendinous slip to the short muscles of the thumb.
The palmaris longus tendon is responsible for exposing the claws in other mammals.
The palmaris longus is a variable muscle, absent in about 16 percent of Caucasians, and less frequently absent in other populations. It may be tendinous above and muscular below; or it may be muscular in the center with a tendon above and below; or it may present two muscular bundles with a central tendon; or finally it may consist solely of a tendinous band.
The muscle may be double, or missing entirely.
Slips of origin from the coronoid process or from the radius have been seen.
Partial or complete insertion into the fascia of the forearm, into the tendon of the Flexor carpi ulnaris and pisiform bone, into the scaphoid, and into the muscles of the little finger have been observed.
Use in tendon grafts
The palmaris longus muscle is the most popular for use in tendon grafts for the wrist due to the length and diameter of the palmaris longus tendon, and the fact that it can be used without producing any functional deformities. When a tendon becomes ruptured in the wrist, the palmaris longus tendon may be removed from the flexor retinaculum and grafted to take the place of the ruptured tendon. The tendons most commonly replaced or supplemented by the palmaris longus tendon when ruptured are the long flexors of the fingers and the flexor pollicis longus tendon.
The palmaris longus muscle itself is a weak flexor, and provides no substantial flexing force that would inhibit movement in the wrist if its tendon was cut and moved elsewhere. If the palmaris longus muscle is not available for harvesting in an individual, the anatomically analogous plantaris muscle in the leg may be taken instead. Using the patient’s own tendon is advantageous, as it does not introduce foreign material into the body.
- PMID 15935531 (PubMed)
- Gray's Anatomy (1918), see infobox
- Thompson NW, Mockford BJ, Cran GW (May 2001). "Absence of the palmaris longus muscle: a population study". Ulster Medical Journal 70 (1): 22–4. PMID 11428320.
- Sebastin SJ, Puhaindran ME, Lim AY, Lim IJ, Bee WH (October 2005). "The prevalence of absence of the palmaris longus--a study in a Chinese population and a review of the literature". Journal of Hand Surgery 30 (5): 525–527. doi:10.1016/j.jhsb.2005.05.003. PMID 16006020.
- Carroll, Will; Gorman, Thomas (June 2009). "Inside Tommy John Surgery". Baseball Prospectus. http://www.baseballprospectus.com/article.php?articleid=3486. Retrieved February 2012.
- Thejodhar, P; Potu, Bhagath Kumar; Vasavi, Rakesh G (2008). "Unusual palmaris longus muscle". Indian Journal of Plastic Surgery 41 (1): 95–96. doi:10.4103/0970-0358.41125. PMID 19753215.
- Wheeless, Clifford R (1996. Web. 04 Dec. 2009). "Palmaris Longus Tendon Graft Harvest". Wheeless' Textbook of Orthopaedics. http://www.wheelessonline.com/ortho/palmaris_longus_tendon_graft_harvest. Retrieved February 2012.
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