The prevalence and distribution of the flexor carpi radialis brevis muscle in the Turkish population

Abstract

The flexor carpi radialis brevis (FCRB) is a very rare anomalous muscle that is usually asymptomatic but may cause various pathologies, such as radial-sided wrist pain. The aim of this study was to determine the prevalence of FCRB in the Turkish population, its location, and sex differences. Forearm, wrist, and hand magnetic resonance images of 849 individuals aged 18–65 years were retrospectively evaluated in this study. The survey found an FCRB prevalence of 4%, with a prevalence of 3.6% among women and of 4.7% among men. However, the difference between the sexes was not statistically significant (p = 0.629). The origin of all 34 FCRBs identified was the distal third of the anterior aspect of the radius; the insertion site of 28 was the second metacarpal bone, whereas that of the remaining 6 was the os trapezium. In conclusion, the data of this study report the prevalence of FCRB for the first time in the Turkish population, which will contribute to radiological and surgical evaluations in the region and help in early and accurate diagnosis of various pathological conditions that may be caused by FCRB.

Flexor Carpi Radialis Brevis: A Case Report

“…Several insertions have been reported in literature including the base of the 2-4 th metacarpal and radial sided carpals [3,7,9,10]; however, this is the second reported case, to our knowledge, of a FCRB traveling through the carpal tunnel. FCRBs are usually found intraoperatively or during postmortem dissection.…”

“…The FCRB is a rare anatomical variation with a prevalence that is unaffected by sex or race; however, the prevalence may increase as ISSN 2563-7142 awareness of this anomalous muscle increases [2,7]. Although most reports on the FCRB suggest it is a rare anatomical anomaly, Mantovani et al report a clinical case series of this anomaly and suggest that the FCRB is relatively common from their experience [12].…”

“…Many anatomical variants of muscle and tendinous structures are present around the wrist and are often found by chance during magnetic resonance imaging (MRI) or other imaging studies, surgical procedures, or cadaveric dissections. The flexor carpi radialis brevis (FCRB) muscle is a rare variant muscle, with incidence ranging from 1.6-7.5% [2][3][4][5][6][7]. The FCRB was first described in 1851 and was given the name flexor carpi radialis brevis vel profundus [8].…”

“…The muscle belly of the FCRB is located in the distal, anterior forearm, where neurovascular structures and tendons are predominant. Previous reports in the literature state that FCRB originates from the volar-radial border of the radius between the radial insertion of the pronator quadratus (PQ) and the origin of the flexor pollicus longus (FPL) [3,5,7]. The insertion of the FCRB is noted to have frequent variations and may be into the bases of the 2-4 th metacarpals or a radial sided carpal bone [3,7,9,10].…”

“…Previous reports in the literature state that FCRB originates from the volar-radial border of the radius between the radial insertion of the pronator quadratus (PQ) and the origin of the flexor pollicus longus (FPL) [3,5,7]. The insertion of the FCRB is noted to have frequent variations and may be into the bases of the 2-4 th metacarpals or a radial sided carpal bone [3,7,9,10]. The FCRB is reported entering the hand via a special osteofibrous tunnel of the FCR, which is separate from the carpal tunnel [10,11]; however, Nakahashi and Izumi [5] report a case where the FCRB passes through the carpal tunnel.…”