Palmaris Longus Muscle - Variation

Variation

The palmaris longus muscle is a variable muscle. The most common variation is its absence. Several in vivo and in vitro studies have documented the prevalence of absence of the PL tendon in different ethnic groups. The overall prevalence of the absence of the PL tendon in Caucasian populations (European and North American) has been reported between 5.5 and 24% . On the other hand, the overall prevalence of absence of the PL tendon in Asian populations (Chinese, Japanese, Indian, Turkish, Malaysian) has been reported between 4.6 and 26.6%. There are also variations related to its form. 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.