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 Table of Contents  
CASE REPORT
Year : 2013  |  Volume : 12  |  Issue : 2  |  Page : 92-94

Contribution of musculocutaneous nerve in the formation of median nerve


1 Department of Anatomy, College of Medicine University of Nigeria, Enugu Campus, Delta State, Nigeria
2 Department of Surgery, Federal Medical Centre Asaba, Delta State, Nigeria

Date of Web Publication27-Feb-2014

Correspondence Address:
A U Agu
Department of Anatomy, College of Medicine University of Nigeria, Enugu Campus
Nigeria
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/1596-2393.127971

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  Abstract 

The median nerve is formed by the union of the lateral and medial roots of median nerve. The musculocutaneous nerve is the terminal branch of the lateral cord of the brachial plexus. There are documented variations in the origins, courses and distributions of these nerves. On routine dissection of an embalmed adult Nigerian male cadaver, the musculocutaneous nerve of the left side was observed to give a contribution/communication in the formation of median nerve after both roots of median nerve have united. The right side of the brachial plexus was examined and the course and distribution of the musculocutaneous and median nerves were found to be without any communication. Variations in the origins and distributions of the brachial plexus had been documented by previous researchers. The communications between median and musculocutaneous nerves were noted to occur in different types and patterns with respect to coracobrachialis muscle. There are known variations in the formation of median nerve. Knowledge of these variations is important to the anatomist, surgeon, neurologist and anaesthetist as injury proximal to the point of communication may give rise to variable clinical presentations and manifestations.

Keywords: Median nerve, musculocutaneous nerve, variation


How to cite this article:
Anyanwu G E, Agu A U, Maduka C O, Esom E A, Ezugworie O J, Ozoemena F N. Contribution of musculocutaneous nerve in the formation of median nerve. J Exp Clin Anat 2013;12:92-4

How to cite this URL:
Anyanwu G E, Agu A U, Maduka C O, Esom E A, Ezugworie O J, Ozoemena F N. Contribution of musculocutaneous nerve in the formation of median nerve. J Exp Clin Anat [serial online] 2013 [cited 2019 Aug 19];12:92-4. Available from: http://www.jecajournal.org/text.asp?2013/12/2/92/127971


  Introduction Top


The median nerve is usually formed by two roots, the lateral root and the medial root arising from the corresponding cords of the brachial plexus. It descends crossing the brachial artery from lateral to medial side and descends without giving any branch in the arm. The musculocutaneous nerve is the terminal branch of lateral cord of brachial plexus and it supplies the coracobrachialis muscle and then pierces it to descend in between the biceps muscle and brachialis muscle and supplies the above muscles and descends as lateral cutaneous nerve of forearm (Sinnatamby 2006, Chitra 2007). Different patterns of communication and variations in the formation and course of the nerves of the brachial plexus have been reported by several authors (Venieratos et al., 1998, Choi et al., 2002). Although the reported incidence may vary, variation in median nerve and musculocutaneous nerve is indisputably one of the most common variations that may be observed in the formation and course of the nerves of the brachial plexus (Venieratos et al., 1998).

The aim of this report was to highlight the contribution of musculocutaneous nerve in the formation of median nerve which is not only anatomically significant but important in clinical and surgical practice.


  Case Report Top


During routine educational dissection of a young Nigerian male cadaver in the Department of Anatomy, College of Medicine, University of Nigeria, Enugu campus, a variation in the formation of median nerve was observed see [Figure 1]. The median nerve in the left arm was formed by three roots: The lateral and medial roots of median nerve as well as a contribution/communication from the musculocutaneous nerve. Both the lateral and medial roots joined first, anterior to the third part of the axillary artery to form the main trunk, while the musculocutaneous nerve gave out a communicating branch to join the median nerve just proximal to the entrance of the musculocutaneous nerve into coracobrachialis. Subsequent courses of both the median and musculocutaneous nerves were found to be normal. The right side of the brachial plexus was also dissected and examined, and the course and distribution of the musculocutaneous and median nerves were found to be without any communication.
Figure 1: The left axilla showing the contribution of musculocutaneous nerve in the formation of median nerve. 1-lateral cord, 2-Medial cord, 3-Medial root of median nerve, 4-Lateral root of median nerve, 5-Musculocutaneous nerve, 6-Contribution from musculocutaneous nerve, 7-Median nerve

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  Discussion Top


Variations and communication between the median nerve and the musculocutaneous nerve were described by many authors in the nineteenth century (Chitra 2007, Anyanwu et al., 2010, Oluyemi et al., 2007). Venieratos and Anagnostopoulou (1998) reported three types of communications between median and musculocutaneous nerves considering the coracobrachialis muscle as the reference point. In type one, the communication was proximal to the entrance of the musculocutaneous nerve into coracobrachialis. In type two, the communication was distal to the muscle and in type three, the nerve and the communicating branch did not pierce the muscle. In our present report, the musculocutaneous nerve sent out a communicating branch to the main trunk of median nerve before piercing the coracobrachialis muscle. This therefore fits in into type one of the report presented by Venieratos and Anagnostopoulou (1998). In the most recent observations recorded by Choi et al., (2002) such communications have been broadly classified into three patterns. In pattern 1, the two nerves are fused. In pattern 2, there was one communicating branch between the musculocutaneous nerve and the median nerve. In pattern 3, two connecting branches are between the two nerves. Our observation is also in keeping with pattern 2 where there is one communicating branch between the musculocutaneous nerve and the median nerve.

Variation in median nerve and musculocutaneous nerve is indisputably one of the most common variations that may be observed in the formation and course of the nerves of the brachial plexus (Chitra 2007, Loukas et al., 2005, Kerr 1918). Venieratos et al., (1998) found 22 communications between the musculocutaneous and median nerves in 16 out of 79 cadavers. In six subjects they were present bilaterally. Nine of these 22 communications were proximal to the entrance of the musculocutaneous nerve into coracobrachialis. Eglseder and Goldman dissected 54 cadaver arms to determine the course and anatomic relationships of the musculocutaneous nerve in the arm. They noticed interconnections between the musculocutaneous nerve and median nerve in 36% of dissections.[9]

Clinical implication of this could be that injury of musculocutaneous nerve proximal to the anastomotic branch between musculocutaneous and median nerve may lead to unexpected presentation of weakness of forearm flexors and thenar muscles (Sunderland 1978).


  Conclusion Top


Variation in musculocutaneous nerve and median nerve is one of the most common variations observed in the origin, course and distribution of brachial plexus. Some of the variations are bilateral but a good number of them are unilateral, as seen in our report. Though there may not be any obvious anatomical and physiological malfunction, knowledge of these variations is important to the anatomist, radiologist, surgeon, neurologist and anaesthesiologist as it may aid in the diagnosis and treatment of some peripheral nerve injuries.

 
  References Top

1.Anyanwu GE, Obikili EN, Esom AE, Ozoemena FN (2010). Prevalence and pattern of communication of median and musculocutaneous nerves with black population: A case study. Int J Biomed Health Sci 4:2.  Back to cited text no. 1
    
2.Chitra R (2007). Various types of intercommunications between musculocutaneous and median nerves: An analytical study. Ann Indian Acad Neurol 10:100-4.  Back to cited text no. 2
    
3.Choi D, Rodriguez-Niedenfuhr M, Vazquez T, Parkin I, Sanudo JR (2002). Patterns of connections between the musculocutaneous and median nerves in the axilla and arm. Clin Anat 15:11-7.  Back to cited text no. 3
    
4.Eglseder WA, Goldman M (1997). Anatomic variations of the musculocutaneous nerve in the arm. Am J Orthop 26 (11): 777-80.  Back to cited text no. 4
    
5.Kerr AT (1918). The brachial plexus of nerves in man. The variations in its formation and branches. Am J Anat 23:285-395.  Back to cited text no. 5
    
6.Loukas M, Aqueelah H (2005). Musculocutaneous and median nerve connections within, proximal and distal to the coracobrachialis muscle. Folia Morphol (Warsz) 64 (2):101-8.  Back to cited text no. 6
    
7.Oluyemi KA, Adesanya OA, Okwuonu CU, Anyanwu, Godson Emeka (2007). Abnormal pattern of brachial plexus formation, an original case report. Int J Neurosurg 4:2.  Back to cited text no. 7
    
8.Sinnatamby CS (2006). Last's Anatomy, Regional and Applied. 11 th ed. Churchill Livingstone: Edinburg. p.:55-8.  Back to cited text no. 8
    
9.Sunderland S (1978). Nerves and nerve injury. In: The median nerve: Anatomical and physiological features: 2 nd ed. Churchill Livingstone: Edinburg. g. 672-7, 691-727.  Back to cited text no. 9
    


    Figures

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Abstract
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Case Report
Discussion
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