Three-headed reversed palmaris longus muscle: a case report and review of the literature

Abstract

The palmaris longus muscle (PLM) is extremely variable both in number and form. We present the first reported case of three-headed reversed PLM in a 36-year old woman. The relevant literature is reviewed. Variations of the muscles of the forearm and specifically the PLM are not uncommon. However, different rates are given for the types and agenesis of PLM. In one study, the incidence of agenesis was 12.8% and other anomalies were 9%. 15 cases of reversed PLM have been reported in the literature. In our case, the three-headed PLM was resected. The patient's symptoms resolved and at 1-year follow-up she remains symptom-free.

Hypertrophy of palmaris longus muscle, a rare anatomic aberration

“…The literature review showed that the pathologies mentioned above primarily develop in cases when the muscular part of the PLM is located distally, and that if this is accompanied by another anomaly like bifid muscle, accessory muscle, hypertrophy of the muscular part then the chance of the development of the pathology seems even higher [1,4,8,15,21,22,25].…”

“…According to literature review, the following variations and anomalies of the PLM may cause pathologies of the forearm: reverse PLM, reverse PLM with multiplication of muscular part (bifid, or 3-headed PLM), accessory PLM, accessory muscles taking their origin from the tendinous part of the PLM [4,8,10,15,16,18,21,22,25].…”

Palmaris Inversus Muscle: A Case Report With Clinical and Surgical Discussions

“…Anatomical studies states that the PLI is more often seen on the left side [13], although other studies describe a higher prevalence of PLI on the right side [11,14,15].…”

“…In the case of a PLI, the use of the right arm, forearm and hand might cause the muscle to hypertrophy, thus causing the ulnar nerve and median nerve compression symptoms [21]. On the other hand, hypertrophic PLM can results in pseudo mass of the forearm [15,21,23]. …”

“…However, an asymptomatic muscle may also be of interest in clinical situations because an unexpected muscular belly in the wrist region can cause difficulties in the interpretation of local radiological images [15,21,23]. Furthermore, difficulties during endoscopic wrist procedures and electromyographic studies of the median nerve may be encountered due to abnormalities of the PLM such as the PLI [1,11].…”