The term ‘ biceps brachii ’ : a misnomer ?

Introduction There are a variety of anatomical variations which can be observed during dissection, diagnosis and surgical procedures. These variations are equally important from a clinical as well as an academic point of view. This report discusses the additional head of the biceps branchii. Case report We noticed the third head of biceps brachii during dissection; the head was arising from the fascia covering the brachialis muscle and getting inserted on the radial tuberosity after merging with the long and short heads of biceps. Conclusion The supernumerary head may have both positive and negative effects. Clinical significance lies in the fact that this additional head may cause compression of musculocutaneous nerve, median nerve and brachial artery, which are in close relation with it and produce compression symptoms. Introduction Double-headed biceps brachii is a powerful supinator and flexor of forearm that is innervated by the musculocutaneous nerve (Mc). The long head arises from the supraglenoid tubercle and the short head from the tip of coracoid process along with coracobrachialis. Conjoint tendon of the long and short head gets inserted on the posterior aspect of radial tuberosity1,2. It is the most variant muscle of this region with 3, 4 and even 7 supernumerary heads. These additional heads are categorized according to their site of origin as superior, infero-medial, and infero-lateral heads. As per previous reports, incidence of additional head of this muscle is 7.1% in Indians, 8% in Chinese, 10% in European whites, 12% in African blacks, 15% in Turkish, 18 % in Japanese, 21.5% in South African blacks, 8.3% in South African whites and 37.5% in Colombians3. Among the supernumerary heads of biceps, humeral head is the most frequent; however, its incidence is low in the Indian population. This case report discusses the additional head of the biceps branchii. Case report Asymmetric architecture in the left brachium of a male cadaver was observed during dissection curriculum for undergraduate students. Biceps was found with a bulky additional head, originating from fascia covering the upper and anteromedial aspect of brachialis. Thereafter, it merged with biceps tendon and attached to the posterior aspect of radial tuberosity. This head was supplied by a branch of Mc. A thin small muscular slip was also arising just below the origin of the additional head of biceps and getting fused with the inner surface of this additional head (Figure 1). Both limbs were carefully dissected and examined. No other abnormality was found. Pictorial presentation of this variation was recorded. Discussion Biceps brachii is known to show frequent variations. Here we found an additional head of the biceps brachii in a North Indian hilly population (Figure 2). Functionally, this variant muscle may act as a pronator of forearm irrespective of the position of the shoulder joint4. * Corresponding author Email: alok.sxna@gmail.com 1 Department of Anatomy, Veer Chandra Singh Garhwali Government Medical Science and Research Institute, Srinagar, Uttarakhand, India 2 Department of Anatomy, Government Medical College, Kota, Rajasthan, India Figure 1: The figure shows the long head (BBL), short head (BBS) and BBT of biceps brachii innervated through Mc. Note the additional muscular slip (1) getting merged with BBT. Figure 2: The figure depicts common tendinous insertion of BBL, BBS, BBT radial tuberosity. A na to m y Case report Page 2 of 2 Co m pe ti n g in te re st s: n on e de cl ar ed . C on fl i ct o f i nt er es ts : n on e de cl ar ed . A ll au th or s co nt rib ut ed to th e co nc ep ti o n, d es ig n, a nd p re pa ra ti o n of th e m an us cr ip t, a s w el l a s re ad a nd a pp ro ve d th e fi n al m an us cr ip t. A ll au th or s ab id e by th e A ss oc ia ti o n fo r M ed ic al E th ic s (A M E) e th ic al ru le s of d is cl os ur e. Licensee OA Publishing London 2013. Creative Commons Attribution Licence (CC-BY) FOR CITATION PURPOSES: Soni S, Ghulyani T, Saxena A, Saraswat NK. The term ‘biceps brachii’: a misnomer? OA Case Reports 2013 Jul 12;2(5):48. Previous reports have revealed the fact that the third head of biceps brachii (BBT) may take its origin from upper, middle and lower portion of humerus, but no significant variation was noticed about its tendinous insertion5–8. A unique variation was observed by Varlekar et al., where BBT was observed to originate from the pectoralis major tendon. It travelled between intervals of the long and short tendon of biceps brachii and was inserted on the radial tuberosity after merging with the tendon of the other two heads9. Embryologically, BBT is considered as a component of brachialis, supplied by Mc, insertion of which has been translocated from the ulna to radius10. Prevalence of BBT is more in males than in females in the Indian population9. Presence of the supernumerary head of biceps may enhance the function of flexion and supination of forearm. Moreover, if its size is large, it may provide more power to biceps tendon2,11. Conclusion The supernumerary head may have both positive and negative effects. Clinical significance lies in the fact that this additional head may cause compression of Mc, median nerve and brachial artery, which are in close relation with it and produce compression symptoms. Any variation is not apparent until it hinders the normal function of an individual. Therefore, it is worth exploring these variations from academic, diagnostic and clinical point of view. As the name implies, ‘biceps’, a Latin origin word, stands for bi (two) + ceps (stem cipit); two headed. We believe that the term ‘biceps’ is a misnomer because it has been observed with 3, 4 and even 7 supernumerary heads. Hence, it would be inappropriate to refer to this muscle as ‘biceps’.


Introduction
Double-headed biceps brachii is a powerful supinator and flexor of forearm that is innervated by the musculocutaneous nerve (Mc).The long head arises from the supraglenoid tubercle and the short head from the tip of coracoid process along with coracobrachialis.Conjoint tendon of the long and short head gets inserted on the posterior aspect of radial tuberosity 1,2 .It is the most variant muscle of this region with 3, 4 and even 7 supernumerary heads.These additional heads are categorized according to their site of origin as superior, infero-medial, and infero-lateral heads.As per previous reports, incidence of additional head of this muscle is 7.1% in Indians, 8% in Chinese, 10% in European whites, 12% in African blacks, 15% in Turkish, 18 % in Japanese, 21.5% in South African blacks, 8.3% in South African whites and 37.5% in Colombians 3 .Among the supernumerary heads of biceps, humeral head is the most frequent; however, its incidence is low in the Indian population.This case report discusses the additional head of the biceps branchii.

Case report
Asymmetric architecture in the left brachium of a male cadaver was observed during dissection curriculum for undergraduate students.Biceps was found with a bulky additional head, originating from fascia covering the upper and anteromedial aspect of brachialis.There-after, it merged with biceps tendon and attached to the posterior aspect of radial tuberosity.This head was supplied by a branch of Mc.A thin small muscular slip was also arising just below the origin of the additional head of biceps and getting fused with the inner surface of this additional head (Figure 1).Both limbs were carefully dissected and examined.No other abnormality was found.Pictorial presentation of this variation was recorded.

Discussion
Biceps brachii is known to show frequent variations.Here we found an additional head of the biceps brachii in a North Indian hilly population (Figure 2).Functionally, this variant muscle may act as a pronator of forearm irrespective of the position of the shoulder joint 4 .Previous reports have revealed the fact that the third head of biceps brachii (BB T ) may take its origin from upper, middle and lower portion of humerus, but no significant variation was noticed about its tendinous insertion [5][6][7][8] .A unique variation was observed by Varlekar et al., where BB T was observed to originate from the pectoralis major tendon.It travelled between intervals of the long and short tendon of biceps brachii and was inserted on the radial tuberosity after merging with the tendon of the other two heads 9 .
Embryologically, BB T is considered as a component of brachialis, supplied by Mc, insertion of which has been translocated from the ulna to radius 10 .Prevalence of BB T is more in males than in females in the Indian population 9 .
Presence of the supernumerary head of biceps may enhance the function of flexion and supination of forearm.Moreover, if its size is large, it may provide more power to biceps tendon 2,11 .

Conclusion
The supernumerary head may have both positive and negative effects.
Clinical significance lies in the fact that this additional head may cause compression of Mc, median nerve and brachial artery, which are in close relation with it and produce compression symptoms.Any variation is not apparent until it hinders the normal function of an individual.Therefore, it is worth exploring these variations from academic, diagnostic and clinical point of view.As the name implies, 'biceps', a Latin origin word, stands for bi (two) + ceps (stem -cipit); two headed.We believe that the term 'biceps' is a misnomer because it has been observed with 3, 4 and even 7 supernumerary heads.Hence, it would be inappropriate to refer to this muscle as 'biceps'.

Figure 1 :
Figure 1: The figure shows the long head (BB L ), short head (BB S ) and BB T of biceps brachii innervated through Mc.Note the additional muscular slip (1) getting merged with BB T.

Figure 2 :
Figure 2: The figure depicts common tendinous insertion of BB L , BB S , BB T radial tuberosity.