Table of Contents  
CASE REPORT
Year : 2016  |  Volume : 9  |  Issue : 2  |  Page : 264-266  

Supernumerary head of biceps brachii and branching pattern of the musculocutaneous nerve


Department of Anatomy, Armed Forces Medical College, Pune, Maharashtra, India

Date of Web Publication1-Mar-2016

Correspondence Address:
Mohan Basavaraj Angadi
Department of Anatomy, Armed Forces Medical College, Pune - 411 040, Maharashtra
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0975-2870.177684

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  Abstract 

During routine dissection by medical undergraduates, third head of the biceps brachii muscle was found on the left side of a 75-year-old male cadaver in a total of 48 arms dissected in Department of Anatomy Armed Forces Medical College, Pune. Biceps brachii is a muscle of arm having two heads hence the name. The most frequent variation of the muscle is in the number of heads with a prevalence range of 9.1-22.9%. The origin of the supernumerary head in this case was from the humerus, between the insertion of the coracobrachialis and the upper part of the origin of the brachialis, and also from the medial intermuscular septum. The supernumerary head joined the common belly. It was supplied by the musculocutaneous nerve which after emerging from brachialis pierced it near the middle and terminated by finally supplying the biceps belly. In our study, 2.08% (1 of 48) of male cadavers were found to have the third head of biceps. The incidence of this variation can be as much as 10% as, shown in previous studies on Indian population, as reported in standard textbooks of anatomy.

Keywords: Biceps brachii, musculocutaneous nerve, supernumerary head


How to cite this article:
Angadi MB, Tandon A, Pandit S, Bhatnagar R. Supernumerary head of biceps brachii and branching pattern of the musculocutaneous nerve. Med J DY Patil Univ 2016;9:264-6

How to cite this URL:
Angadi MB, Tandon A, Pandit S, Bhatnagar R. Supernumerary head of biceps brachii and branching pattern of the musculocutaneous nerve. Med J DY Patil Univ [serial online] 2016 [cited 2020 Aug 8];9:264-6. Available from: http://www.mjdrdypu.org/text.asp?2016/9/2/264/177684


  Introduction Top


Biceps brachii is a muscle of the anterior compartment of the arm and the only flexor muscle crossing both the shoulder and elbow joint. Described as two-headed muscle (biceps) long head-arises from supraglenoid tubercle and short head from tip of the coracoid process. [1] Two heads join to form a common tendon inserts on to the radial tuberosity, and bicipital aponeurosis merges with deep fascia of forearm, innervated by musculocutaneous nerve, supplied by brachial and anterior circumflex humeral artery, this muscle has the most frequent anatomical variations. [2] Variations like accessory fascicles from the coracoid process, pectoralis major, head or capsule of the humerus, and shaft (humeral head of biceps brachii) may present. Most frequent variation of the muscle is in the number of heads with a prevalence range of 9.1-22.9%. [3],[4]


  Case Report Top


A case of the third head of the biceps brachii muscle was found on the left side of a 75-year-old male cadaver in a total of 48 arms dissected in Department of Anatomy, Armed Forces Medical College, Pune.

The origin of the supernumerary head in this case was from the humerus, between the insertion of the coracobrachialis and the upper part of the origin of the brachialis, and also from the medial intermuscular septum as shown in the [Figure 1] and [Figure 2]. The supernumerary head joined the common belly. It was supplied by the musculocutaneous nerve which after emerging from brachialis pierced it near the middle and terminated by finally supplying the biceps belly as shown in the [Figure 3].
Figure 1: Third head of biceps brachii. 1: Biceps common tendon, 2: Brachialis, 3: Brachioradialis, 4: Deltoid, 5: Forearm

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Figure 2: Origin and insertion of the third head of biceps muscle. 1: Biceps common tendon, 2: Brachialis

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Figure 3: Third head supplied by the musculocutaneous nerve. 6: Lateral cutaneous nerve of forearm

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  Discussion Top


In literature biceps brachii muscle presents a wide range of variations. Most common variation is the muscle arising from the proximal humerus. Is to report the occurrence of the third head of biceps brachii in a sample of the Indian population. Standard textbook of anatomy reported the incidence of this variation to be as much as 10%. [5] Asvat et al. reported an incidence of 21.5% in their study group consisting of blacks. [6]

According to previous studies incidence of this anomaly varies in a different population. Chinese 8%, European white 10%, African black 12%, Japanese 18%, South African blacks 20.55%, and 37.5% in Colombians. In our study, we have observed the incidence of the third head of biceps brachii in 2.08%of the cases. According to Khaledpour, male cadavers were found to have this variant in 31.2% of the cases. [4],[7],[8]

In our study, 2.08% (1 of 48) of male cadavers were found to have the third head of biceps. Embryological observations by Testut described this variation of the third head of biceps brachii as a portion of the brachialis muscle supplied by the musculocutaneous nerve, in which its distal insertion has been translocated from the ulna to the radius. In the literature biceps brachii muscle presents a wide range of variations. [1],[5]

Its morphological variations have great clinical significance for surgeons, orthopedic surgeons, anesthetists, neurologists, and anatomists. Knowledge of the morphological variations of biceps muscle provides a better preoperative evaluation, safe surgical intervention to the arm and better postoperative outcomes.

Surgeons and especially orthopedic surgeons should bear in mind muscular variations like the one reported in the present study, since unusual clinical signs and symptoms at the upper limb could be attributed to compression or entrapment of neurovascular bundles by these anatomical structures. Knowledge of these variations is necessary to avoid complications during surgical exposures. [7] Special attention is needed during the anterior exposure of the arm or shoulder. Recognition and mobilization of the accessory bicipital head is necessary for adequate exposure of the shoulder joint through a deltopectoral incision. Moreover, in humeral fractures, the supernumerary head may cause unusual displacement of the fracture ends due to the alteration of the biomechanical forces applied to the humerus. [8]


  Conclusion Top


The results of the present study compared with that of previous studies from the medical literature shows that the occurrence of a third head of the biceps brachii muscle is relatively rare in Indians. [4]

Knowledge of the existence of the third head of biceps brachii may become significant in preoperative diagnosis and during surgery of the upper limb particularly for orthopedic surgeons.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

 
  References Top

1.
Williams PL, Bannister LH, Berry MM, Collins P, Dyson M, Dussek, et al., editors. Gray′s Anatomy: The Anatomical Basis of Medicine and Surgery. 38 th ed. Edinburgh: ELBS Churchill Livingstone; 1995. p. 843.  Back to cited text no. 1
    
2.
Testut L. En: Tratado de Anatomia Humana. Barcelona: Salvat; 1902.  Back to cited text no. 2
    
3.
Sargon MF, Tuncali D, Celik HH. An unusual origin for the accessory head of biceps brachii muscle. Clin Anat 1996;9:160-2.  Back to cited text no. 3
    
4.
Nayak SR, Prabhu LV, Sivanandan R. Third head of biceps brachii: A rare occurrence in the Indian population. Ann Anat 2006;188:159-61.  Back to cited text no. 4
    
5.
Williams PL, Dyson M. Gray′s Anatomy. 37 th ed. London: ELBS with Churchill Livingstone; 1989. p. 614-5.  Back to cited text no. 5
    
6.
Asvat R, Candler P, Sarmiento EE. High incidence of the third head of biceps brachii in South African populations. J Anat 1993;182 (Pt 1):101-4.  Back to cited text no. 6
    
7.
Warner JJ, Paletta GA, Warren RF. Accessory head of the biceps brachii. Case report demonstrating clinical relevance. Clin Orthop Relat Res 1992;280:179-81.  Back to cited text no. 7
    
8.
Kopuz C, Sancak B, Ozbenli S. On the incidence of third head of biceps brachii in Turkish neonates and adults. Kaibogaku Zasshi 1999;74:301-5.  Back to cited text no. 8
    


    Figures

  [Figure 1], [Figure 2], [Figure 3]



 

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Abstract
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Discussion
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