Although the flexor pollicis longus is known to show the additional head of the origin, the occurrence of its additional tendons in the carpal tunnel are seldom reported. The presence of such additional tendons in the carpal tunnel cannot be overlooked during the radiological and
surgical procedures in this region. Herein, we report a rare case of additional muscle belly of flexor pollicis longus. The additional muscle belly after a short course divided into three tendons. All three tendons entered the carpal tunnel along with flexor pollicis longus, passing deep to the flexor retinaculum. Within the carpal tunnel, two of these tendons fused and terminated by merging with the undersurface of the flexor retinaculum. The third tendon terminated by joining the flexor digitorum superficialis tendon for the index finger, in the palm. An additional slip of the first lumbrical muscle took origin from the third tendon of the additional muscle belly of flexor pollicis longus. Further, the embryological basis and clinical significance of current case is discussed.
References
[1]
Williams, P.L., Bannister, L.H., Berry, M.M., Collins, P., Dyson, M., Dussek, J.E. and Ferguson, M.W. (1995) Gray’s anatomy: The anatomical basis of medicine and surgery. 38th Edition, Churchill Livingstone, New York.
[2]
Wood, J. (1868) Variations in human myology. Proceedings of the Royal Society of London, 15, 518-846.
[3]
Dykes, J. and Anson, B.J. (1944) The accessory tendon of the flexor pollicis longus muscle. The Anatomical Record, 90, 83-87. http://dx.doi.org/10.1002/ar.1090900111
[4]
Malhotra, V.K., Sing, N.P., Tewari, S.P. (1982) The accessory head of the flexor pollicis longus muscle and its nerve supply. Anatomischer Anzeiger, 151, 503-505.
[5]
Jones, M., Abrahams, P.H., Sanudo, J.R., Campillo, M. (1997) Incidence and morphology of accessory heads of flexor pollicis longus and flexor digitorum profundus (Gantzer’s muscle). Journal of Anatomy, 191, 451-455.
http://dx.doi.org/10.1046/j.1469-7580.1997.19130451.x
[6]
Hemmady, M.V., Subramanya, A.V. and Mehta, I.M. (1993) Occasional head of flexor pollicis longus muscle: A study of its morphology and clinical significance. Journal of Postgraduate Medicine, 39, 14-16.
[7]
Mahakkanukrauh, P., Surin, P., Ongkana, N., Sethadavit, M. and Vaidhayakarn, P. (2004) Prevalence of accessory head of flexor pollicis longus muscle and its relation to anterior interosseus nerve in Thai population. Clinical Anatomy, 17, 631-635.
http://dx.doi.org/10.1002/ca.20016
[8]
Macalister, A. (1875) Additional observatins on muscular anomalies in human anatomy (third series), with a catalogue of the principal musclular variations hitherto published. Transactions of the Royal Irish Academy Science, 25, 1-134.
[9]
Linburg, R.M. and Comstock, B.E. (1979) Anomalous tendon slips from the flexor pollicis longus to flexor digitorum profundus. The Journal of Hand Surgery, 4, 79-83. http://dx.doi.org/10.1016/S0363-5023(79)80110-0
[10]
Vishal, K., Naveen, N.S., Murlimanju, B.V., Prima, S.D. (2011) A rare muscular variation in the flexor compartment of the forearm. The International Journal of Acoustics and Vibration, 4, 115-116.
[11]
Jones, M., Abrahams, P.H. and Sanudo, J.R. (1997) Case report: Accessory head of the deep forearm flexors. Journal of Anatomy, 191, 313-314.
http://dx.doi.org/10.1046/j.1469-7580.1997.19120313.x
[12]
Lewis, W.H. (1910) The development of the muscular system. In: Keibel, F. and Mall, F.P., Eds., Manual of Human Embryology, J. B. Lippincott, Philadelphia, 492- 493.
[13]
Bergman, R.A., Thompson, S.A., Afifi, A.K. and Saadeh, F.A. (1988) Compendium of human anatomic variation. Urban and Schwarzenberg, Munich.
[14]
Ajmani, M.L. (2001) Morphological variations of lumbrical muscles in the human hand with some observations on its nerve supply. Medical Journal of the Iranian Hospital, 3, 20-25.
[15]
Koizumi, M., Kawai, K., Honma, S. and Kodma, K. (2002) Anomalous lumbrical muscles arising from the deep surface of flexor digitorum superficialis muscles in man. Annals of Anatomy, 184, 387-392.
http://dx.doi.org/10.1016/S0940-9602(02)80062-0
[16]
Entin, M.A. (1968) Carpal tunnel syndrome and its variants. Surgical Clinics of North America, 48, 1097-1112.
[17]
Ametewee, K., Harris, A. and Samuel, M. (1985) Acute carpal tunnel syndrome produced by anomalous flexor digitorum superficialis indicis muscle. Journal of Hand Surgery (European Volume), 10, 83-84.
http://dx.doi.org/10.1016/S0266-7681(85)80025-5
[18]
Kiztan, T. (1986) Carpal tunnel syndrome caused by a rare tendon variation. Handchirurgie, Mikrochirurgie, Plastische Chirurgie, 18, 77-78.
