Background. Knowledge of anatomical variations of posterior cord and its branches is important not only for the administration of anaesthetic blocks but also for surgical approaches to the neck, axilla, and upper arm. The present study aimed to record the prevalence of such variations with embryological explanation and clinical implication. Material and Method. 37 formalin-preserved cadavers, that is, 74 upper extremities from the Indian population, constituted the material for the study. Cadavers were dissected during routine anatomy classes for medical undergraduate. Dissection includes surgical incision in the axilla, followed by retraction of various muscles, to observe and record the formation and branching pattern of posterior cord of brachial plexus. Results. Posterior cord was formed by union of posterior division of C5 and C6 roots with posterior division of middle and lower trunk (there was no upper trunk) in 16.2% of upper extremities. Posterior cord of brachial plexus was present lateral to the second part of axillary artery in 18.9% of upper extremities. Axillary nerve was taking origin from posterior division of upper trunk in 10.8% upper extremities and thoracodorsal nerve arising from axillary nerve in 22.9% upper extremities. Conclusion. It is important to be aware of such variations while planning a surgery in the region of axilla as these nerves are more liable to be injured during surgical procedures. 1. Introduction Posterior cord of brachial plexus is formed by union of posterior division of upper, middle, and lower trunk of brachial plexus. It lies posterior to, second part of axillary artery. The posterior cord of brachial plexus after giving upper subscapular, thoracodorsal, lower subscapular, and axillary nerve in the axilla continues distally as the radial nerve [1]. Knowledge of the variations of posterior cord and its branches is important for the administration of anaesthetic blocks, surgical approaches to the neck, axilla, and upper arm [2, 3]. The present study describes the variations of posterior cord observed in population from central India. 2. Material and Method The formalin-fixed 37 cadavers, that is, 74 upper extremities constitute the material for study. During routine dissection of axilla and supraclavicular region of medical undergraduates in L.N. Medical College Bhopal, the skin and various muscles were reflected and superficial fascia and deep fascia were separated to visualize the formation and branching pattern of posterior cord. 3. Results We recorded variations in the formation, location, and branching
References
[1]
S. Standring, “Pectoral girdle and shoulder region,” in Gray’s Anatomy, the Anatomical Basis of Clinical Practice, pp. 780–781, Churchill Livingstone, New York, NY, USA, 40th edition, 2008.
[2]
L. E. Ballesteros and L. M. Ramirez, “Variations of the origin of collateral branches emerging from the posterior aspect of the brachial plexus,” Journal of Brachial Plexus and Peripheral Nerve Injury, vol. 2, no. 1, article 14, 2007.
[3]
K. M. R. Bhat and V. Girijavallabhan, “Variation in the branching pattern of posterior cord of brachial plexus,” Neuroanatomy, vol. 7, pp. 10–11, 2008.
[4]
V. P. S. Fazan, A. D. S. Amadeu, A. L. Caleffi, and O. A. Rodrigues Filho, “Brachial plexus variations in its formation and main branches,” Acta Cirurgica Brasileira, vol. 18, no. 5, pp. 14–18, 2003.
[5]
P. Chaudhary, R. Singla, G. Kalsey, and K. Arora, “Branching pattern of the posterior cord of brachial plexus: a cadaveric study,” Journal of Clinical and Diagnostic Research, vol. 5, no. 4, pp. 787–790, 2011.
[6]
R. K. Singla, R. Mahajan, R. Sharma, and T. Sharma, “Bilateral non-formation of upper trunk of the brachial plexus with a unilateral communication between the musculocutaneous nerve and median nerve: a case report,” Journal of Clinical and Diagnostic Research, vol. 5, no. 8, pp. 1637–1640, 2011.
[7]
J. Villamere, S. Goodwin, M. Hincke, and A. Jalali, “A brachial plexus variation characterized by the absence of the superior trunk,” Neuroanatomy, vol. 8, pp. 4–6, 2009.
[8]
J. H. Stevens, “Brachial plexus paralysis. By J.H. Stevens, M.D., 1934,” Clinical Orthopaedics and Related Research, no. 237, pp. 4–8, 1988.
[9]
N. Z. Keibel and F. P. Mall, “Nerves of the arm and leg,” in Manual of Human Embryology, pp. 122–128, J. B. Lippincott, Philadelphia, Pa, USA, 1st edition, 1912.
[10]
H. D. Sannes, T. A. Reh, and W. A. Harris, “Axon growth and guidance,” in Development of Nervous System, pp. 189–197, Academic Press, New York, NY, USA, 2000.
[11]
R. A. Miller, “Comprative studies upon the morphology and the distribution of the brachial plexus,” American Journal of Anatomy, vol. 54, no. 1, pp. 143–175, 1932.
[12]
M. Jamuna, “Clinically significant variations of the cords of the brachial plexus in relation to axillary artery,” International Journal of Anatomical Variations, vol. 4, pp. 9–11, 2011.
[13]
N. Satyanarayana, N. Vishwakarma, G. P. Kumar, R. Guha, A. K. Datta, and P. Sunitha, “Variation in relation of cords of brachial plexus and their branches with axillary and brachial arteries—a case report,” Nepal Medical College Journal, vol. 11, no. 1, pp. 69–72, 2009.
[14]
M. Jamuna, “A rare variation in the mode of termination of posterior cord of brachial plexus,” International Journal of Anatomical Variations, vol. 3, pp. 95–96, 2010.
[15]
V. Matejcik, “Aberrant formation and clinical picture of brachial plexus from the point of view of a neurosurgeon,” Bratislavske Lekarske Listy, vol. 104, no. 10, pp. 291–299, 2003.
[16]
J. M. Muthoka, S. R. Sinkeet, S. H. Shahbal, L. C. Matakwa, and J. A. Ogeng'o, “Variations in branching of the posterior cord of brachial plexus in a Kenyan population,” Journal of Brachial Plexus and Peripheral Nerve Injury, vol. 6, no. 1, article 1, 2011.
