Palmaris longus muscle
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| Palmaris longus muscle | ||
|---|---|---|
 | ||
| Front of right upper extremity. (Palmaris longus labeled at bottom, second from left.) | ||
 | ||
| Transverse section across distal ends of radius and ulna. (Palmaris longus labeled at center top.) | ||
| Latin | musculus palmaris longus | |
| Gray's | subject #125 446 | |
| Origin: | medial epicondyle of humerus (common flexor tendon) | |
| Insertion: | palmar aponeurosis | |
| Artery: | ulnar artery | |
| Nerve: | median nerve | |
| Action: | wrist flexor | |
| Antagonist: | Extensor carpi radialis brevis, Extensor carpi radialis longus, Extensor carpi ulnaris | |
| Dorlands/Elsevier | m_22/12550072 | |
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.
It is a slender, fusiform muscle, lying on the medial side of the flexor carpi radialis.
It arises from the medial epicondyle of the humerus by the common flexor tendon, from the intermuscular septa between it and the adjacent muscles, and from the antibrachial fascia.
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.
It 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.
Variation
The palmaris longus is a variable muscle, absent in about 16 percent of Caucasians[1], and less frequently absent in other populations[2]. 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.
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.
Additional images
Musculuspalmarislongus.png
Front of the left forearm. Superficial muscles. |
 Cross-section through the middle of the forearm. |
 Transverse section across the wrist and digits. |
 The palmar aponeurosis. |
 The muscles of the thumb. |
 The muscles of the left hand. Palmar surface. |
 The radial and ulnar arteries. |
Due to its apparent unimportance, it is often used as a replacement for other tendons should injury arise.
References
- ↑ 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): 525-7. PMID 16006020.
External links
This article was originally based on an entry from a public domain edition of Gray's Anatomy. As such, some of the information contained herein may be outdated. Please edit the article if this is the case, and feel free to remove this notice when it is no longer relevant.
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Acknowledgement and Attribution Regarding Sources of Content
Some of the initial content on this page may be incorporated in part from copyleft sources in the public domain including wikis such as Wikipedia and AskDrWiki. Drug information for patients came from the The National Library of Medicine. Infectious disease information may have come from the Centers for Disease Control (CDC). Differential Diagnoses are drawn from clinicians as well as an amalgamation of 3 sources: 1.The Disease Database; 2. Kahan, Scott, Smith, Ellen G. In A Page: Signs and Symptoms. Malden, Massachusetts: Blackwell Publishing, 2004:3; 3. Sailer, Christian, Wasner, Susanne. Differential Diagnosis Pocket. Hermosa Beach, CA: Borm Bruckmeir Publishing LLC, 2002:7 .
