An additional muscle belly of the first lumbrical muscle

Abstract

Introduction: Lumbrical muscles play a vital role in the precision movements of the hand, along with the thenar, hypothenar and interossei muscles. The variation in the lumbrical muscle is clinically significant.

MÚSCULO LUMBRICAL COMO CAUSA DE SÍNDROME DEL TÚNEL CARPIANO. Lumbrical muscle within the carpal tunnel as a cause of carpal tunnel syndrome.

“…Nac. (Nayak et al, 2008;Trivedi et al, 2016;Shimizu et al, 2015). Se han descrito múltiples variantes en los músculos: variantes de número (entre 5 y 7 lumbricales en vez de los 4 habituales), inserciones sobre el flexor superficial, inserción sobre huesos y músculos del antebrazo o el flexor del pulgar, músculos con dos cuerpos en vez de uno (variante para los lumbricales primero y segundo) (Testut, 1922;Trivedi et al, 2016).…”

New insights into the origin of the lumbrical muscles of the foot: tendinous slip of the flexor hallucis longus muscle

“…The lumbrical arose from both the tendon of the FDL and the tendinous slip of the FHL that formed the long flexor tendon in most specimens. Thus, these origins of the lumbricals in the foot are thought as normal anatomy while the additional origins of the first lumbrical in the hand are considered as variations [7,9,10,12,15,17,24]. The lumbrical has been a consistent contributor to the active component, as reflected by EMGs in certain exercises [20].…”

Aberrant deep flexor muscles of the forearm associated with the accessory origin of first lumbrical muscle

“…2,4,13,14,18,19 Causes of CTS with respect to the lumbricals include incursion of the lumbrical muscles within the tunnel during finger movements, 20,21 hypertrophy of the lumbricals, 18 anatomic variants such as abnormally long lumbrical muscles 19 and aberrant tendinous origin of the first lumbrical. 2,4,13,14 The present findings will supplement our knowledge of muscle variations in the antebrachial and carpal region and should also be considered in the aetiology of CTS, the awareness of which will facilitate safe surgery of median nerve entrapment syndromes. The identification of muscular variations in the carpal region is important for chiropractors as well, who use manoeuvres to alleviate pain resulting from CTS.…”

“…1 Anatomical variations in muscles in the superficial flexor compartment of the forearm, especially those of flexor digitorum superficialis (FDS), are quite common, among which many are associated with anomalous accessory first lumbricals. [2][3][4] Variations of flexor digitorum profundus (FDP) in the deep flexor compartment are not rare. But, rarely, a lumbrical muscle may arise from the deep flexors in the forearm 5 even though variations in their attachments are common.…”