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
Actions	wrist flexor
Antagonist	Extensor carpi radialis brevis, Extensor carpi radialis longus, Extensor carpi ulnaris

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.^[1]

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.

Contents 1 Course 2 Variation 3 Use In Tendon Grafts 4 Additional images 5 References 6 External links

[edit] Course

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.

The palmaris longus tendon is responsible for exposing the claws in lower vertebrates.

[edit] Variation

The palmaris longus is a variable muscle, absent in about 16 percent of Caucasians,^[2] and less frequently absent in other populations.^[3] 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.

[edit] 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 ^[4]. 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 ^[5].

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 ^[6]. Using the patient’s own tendon is advantageous, as it does not introduce foreign material into the body.

[edit] Additional images

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.

[edit] References

1. ^ Sebastin, S. J.; Lim, A. Y. T.; Bee, W. H.; Wong, T. C. M.; Methil, B. V. (2005). "Does the absence of the palmaris longus affect grip and pinch strength?". Journal of hand surgery (Edinburgh, Scotland) 30 (4): 406–408. doi:10.1016/j.jhsb.2005.03.011. PMID 15935531.  edit
2. ^ 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. 
3. ^ 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. 
4. ^ Carroll, Will, and Thomas Gorman. "Inside Tommy John Surgery." Baseball Prospectus. Prospectus Entertainment Ventures, 15 June 2009. Web. 04 Dec. 2009. <http://www.baseballprospectus.com/article.php?articleid=3486>
5. ^ Thejodhar, P., Bhagath Kumar Potu, and Rakesh G. Vasavi. "Unusual palmaris longus muscle." Indian Journal of Plastic Surgery 41.1 (2008): 95-96. PubMed. Web. 3 Dec. 2009. <http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2739544/>.
6. ^ Wheeless, Clifford R. "Palmaris Longus Tendon Graft Harvest - Wheeless' Textbook of Orthopaedics." Welcome to Wheeless' Textbook of Orthopaedics - Wheeless' Textbook of Orthopaedics. Duke Orthopaedics, 1996. Web. 04 Dec. 2009. <http://www.wheelessonline.com/ortho/palmaris_longus_tendon_graft_harvest>.

[edit] External links

• LUC pl
• -1019936742 at GPnotebook
• PTCentral

This article was originally based on an entry from a public domain edition of Gray's Anatomy. As such, some of the information contained within it may be outdated.

v • d • e List of muscles of upper limbs (TA A04.6, GA 4.432) Shoulder deltoid · rotator cuff (supraspinatus, infraspinatus, teres minor, subscapularis) · teres major fascia: Deltoid fascia · Supraspinous fascia · Infraspinous fascia Arm (compartments) Anterior coracobrachialis · biceps brachii · brachialis Posterior triceps brachii · anconeus · Articularis cubiti Fascia Axillary sheath · Axillary fascia · Brachial fascia · intermuscular septa (Lateral, Medial) Other spaces (Quadrangular space, Triangular space, Triangular interval) Forearm Anterior superficial: pronator teres · palmaris longus · flexor carpi radialis · flexor carpi ulnaris · flexor digitorum superficialis deep: pronator quadratus · flexor digitorum profundus · flexor pollicis longus Posterior superficial: mobile wad (brachioradialis, extensor carpi radialis longus and brevis) · extensor digitorum · extensor digiti minimi · extensor carpi ulnaris deep: supinator · anatomical snuff box (abductor pollicis longus, extensor pollicis brevis, extensor pollicis longus) · extensor indicis Fascia Bicipital aponeurosis · common tendons (Extensor, Flexor) · Antebrachial fascia Other Cubital tunnel Hand Lateral volar thenar (opponens pollicis, flexor pollicis brevis, abductor pollicis brevis) · adductor pollicis Medial volar hypothenar (opponens digiti minimi, flexor digiti minimi brevis, abductor minimi digiti) · palmaris brevis Intermediate lumbrical · interossei (dorsal, palmar) Fascia posterior: Extensor retinaculum · Extensor expansion anterior: Flexor retinaculum · Palmar aponeurosis

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