|Year : 2014 | Volume
| Issue : 3 | Page : 129-132
A morphological study of third head of biceps brachii in human cadavers with its clinical implications
Chandni Gupta , Antony , Sylvan D'souza
Department of Anatomy, Kasturba Medical College, Manipal University, Manipal, Karnataka, India
|Date of Web Publication||7-Oct-2014|
Department of Anatomy, Kasturba Medical College, Manipal University, Manipal - 576 104, Karnataka
Source of Support: None, Conflict of Interest: None
Background: Muscular variations are relatively fewer when compared to vascular variations. A few muscles show extra heads of origin apart from their original heads. One such muscle which has extra heads of origin is biceps brachii (BB). Understanding of these extra heads is significant in handling injuries of the muscle and in tendon reconstruction operations. So, the aim of this study was to look for the incidence of the third head of the biceps brachii. Materials and Methods: The study was carried out on 24 cadaveric upper limbs. Dissection of the front of arm was done and the origin and insertion of the BB was looked. Any additional head if present was particularly looked for and photographed. Results: We found the three headed BB unilaterally in three male cadavers, one belonging to the left side and two to right side. The third head of BB originated near the insertion of the CB and at the origin of the brachialis in two cases and in both cases it goes and merges with the other two heads and insert into the posterior part of radial tuberosity. In one case it originates along with the long head of BB and its tendon goes and insert into the deep fascia of the arm. Conclusion : These all variations in the study should be known to the orthopedic surgeons during treatment of the bones fractures in this region because sometime the presence of third head may cause unusual bone displacement subsequent to fracture.
Keywords: Biceps brachii, bone displacement, median nerve, third head
|How to cite this article:|
Gupta C, D'souza S. A morphological study of third head of biceps brachii in human cadavers with its clinical implications. Saudi J Health Sci 2014;3:129-32
| Introduction|| |
Biceps brachii (BB) is a dual headed flexor muscle of flexor compartment of upper arm, originates proximally with a long head from supraglenoid tubercle and short head from coracoid process of scapula. Distally these heads join to form a common tendon, which gets inserted to the posterior part of the radial tuberosity. This muscle chiefly contributes to the flexion and supination of forearm. Some aponeurotic and tendinous fibers go and insert into the bicipital aponeurosis. 
The extra heads of BB muscle have clinical significance as they might confuse surgeons who perform surgeries on the arm and might lead to iatrogenic injuries or the extra head might cause compression of vital neurovascular structures in the upper limb. Association of third head with unusual bone displacement following fracture has significance in surgical procedure. 
The third head may offer extra strength to the Biceps during supination of the forearm and elbow flexion regardless of shoulder position. 
The extra head of BB muscle is remarkable not only to anatomists but also to the clinicians, from the phylogenetic point of view as well as from the surgical view due to the partial entrapment of either the musculocutaneous or median nerve in certain cases. 
From a clinical perspective, muscle anomalies are hard to discriminate from soft tissue tumors. The presence of an anomalous muscle in and around the elbow region may cause high median nerve palsy and compression of the brachial artery. 
It is recognized that the development of the BB muscle is likely to affect the course and the branching pattern of musculocutaneous nerve. , This may have clinical association as the musculocutaneous nerve is subjected to compression by the bulky third head. Thus, knowledge on such variations will be significant during surgical operations of the arm as well as in detecting the nerve injuries. Additionally, it has been stated that any variant nerve with an anomalous origin, course and distribution is liable to to accidental damages and impairments. 
This is further verified by the point that supernumerary heads of the BB muscle have been reported to compress the adjacent neurovascular structures leading to inaccurate interpretations during surgical procedures. 
Therefore, thorough understanding of this variation is significant for surgical interventions of the arm, nerve compression syndromes and in mysterious pain syndromes in the arm or shoulder region. So, the aim of this study was to look for the incidence and morphological features of the third head of the biceps brachii muscle.
| Materials and methods|| |
The study was carried out on 24 cadaveric upper limbs. Dissection of the front of arm was done. A longitudinal incision was given at the anterior aspect of the arm from the acromion process of scapula to a point 2.5 cm below the level of elbow joint. A horizontal incision was given at both ends of the longitudinal incision. Subcutaneous fat was removed from both superficial and deep fascia and a BB muscle was looked for. After appropriate dissection extra heads with their origin and insertion are looked for and photographed.
| Results|| |
We found the three headed BB unilaterally in three male cadavers, one belonging to the left side and two to right side. While the short and long head had a normal origin, in two cases the third head originated near the insertion of the coracobrachialis (CB) and at the origin of the brachialis and in both cases it goes and merges with the other two heads and insert into the posterior part of radial tuberosity. One was very thick [Figure 1] another was thick [Figure 2].
In third case it originates along with the long head of BB and then the third head crosses the musculocutaneous and median nerve in the middle of arm and then finally its tendon goes and insert into the deep fascia of the arm [Figure 3].
|Figure 1: 3 heads of biceps brachii (BB). Very thick one originating, near the insertion of the CB and at the origin of the brachialis and goes and merges with the other two heads and insert into the posterior part of radial tuberosity. MN-Median nerve|
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|Figure 2: 3 heads of biceps brachii (BB). Thick one originating, near the insertion of the CB and at the origin of the brachialis and goes and merges with the other two heads and insert into the posterior part of radial tuberosity. MN -Median nerve|
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|Figure 3: Another 3 heads of biceps brachii (BB). Originating along with the long head of BB and then the third head crosses the musculocutaneous and median nerve in the middle of arm and then finally its tendon goes and insert into the deep fascia of the arm|
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| Discussion|| |
BB muscle morphological variants have great clinical importance for surgeons, orthopedic surgeons, anesthetists, neurologists and anatomists. Awareness of the morphological variants of biceps muscle delivers better pre-operative evaluation, safe surgical intervention within the arm and better postoperative results. 
Sreedevi and colleagues found two cases where biceps was having the extra head. In both case she found that the third head was arising from the humerus at the insertion of CB, and it goes and attached to bicipital aponeurosis. In first case she also got fourth head which was also arising from the humerus at the insertion of CB and also from the tendinous insertion of deltoid muscle and it goes and join the under surface of main muscle just above the elbow joint.  In our study we got the origin from the same place in two cases but they both and goes inserted to the two other heads of biceps brachii.
Shashikala and Ashwini found one case of three head of BB. They found that the third head of BB arose from upper third of humerus at the V shaped insertion of deltoid muscle. It goes and merged with other two heads to form common tendon and was inserted on posterior part of radial tuberosity.  We also got similar type of two cases in our study.
Cheema and Singla found the three headed BB in three male cadavers. The third head originated near the insertion of the CB it goes and finally insert into the muscle belly in two cases and into the bicipital aponeurosis in one case.  We also got two similar cases like their first two cases, but their third case was different which we didn't have in our study.
Kumar et al., observed three heads of biceps on both sides of a male cadaver (3.33%) out of 96 cases studied. The anomalous third head arose from the 'V' shaped insertion of the deltoid muscle on the humerus. And it fuses with the common belly of the muscle well before the bicipital tendon and its aponeurosis.  In our study we didn't get any such case.
Meguid and Ilayperuma et al., found a three-headed BB muscle and the additional head originated from the middle of the anteromedial surface of the humerus and it goes and inserted into the proximal part of the posterior aspect of the common biceps tendon. This common tendon was inserted into the radial tuberosity of radius. , In our study we didn't get any such case.
Avadhani and Chakravarthi found BB with three heads in 16.67% of cases; one had rare four headed BB (2.08%); one had unusual non united two heads of BB (2.08%); one had the bicipital aponeurosis merging with the brachioradialis (2.08%). In the three headed BB the third head was originating from the humerus and it goes and inserted into the radial tuberosity by a common tendon with the long and short heads. We also got two cases similar to them. In the four headed BB the accessory third head was mainly arising from the anterolateral surface of shaft of humerus and joined the long head at the level where the latter joined the short head. The fourth head arising from the short head and inserting in to the antero-medial surface of shaft of humerus above the insertion of CB. 
Swamy and co-researchers found a tendinous slip or cord which was arising from the medial surface of the proximal part of short head of BB muscle and its tendon and it goes and blended with the upper part of medial intermuscular septum.  In our study we didn't get any such case.
Govindarajan and Meenakshisundaram found an additional head of BB which was found to take origin from the lower end of the shaft of the humerus medial to the origin of brachialis muscle and finally it joined with the tendon of BB along the medial side of the muscle above the elbow joint.  We also got similar cases in our studies.
Bapat found a third head of BB which was originating from the deltopectoral fascia at the lower end of deltopectoral groove and it goes and fuses with common belly formed by the long and short heads of the muscle.  In our study we didn't get any such case.
Jayanthi and Elezy found supernumerary heads of BB in 10.8% of cases. Where biceps had three heads of origin, 15.2% were males and 2.5% females. Accessory heads were more on left side 6.7% and 5% on right side. Bilateral triple heads were observed in one case. In most of the muscles the main bulk is formed in the upper third of arm. 
Gupta and Ray found an additional head of biceps muscle originated from humerus and got inserted to the bicipital tendon.  In our study we didn't get any such case.
Nasr and Hussein found the incidence of anatomical variations of biceps muscle was equal in both male and female cadavers (10%) with predominance of the left side (7%). The three-headed BB muscle was noticed in 7% (4% male and 3% female), while the four-headed biceps was seen in 2 (2%) left limbs, 1 male and 1 female. The third head of the biceps muscle arose from the anteromedial aspect of humerus, between the CB insertion and the brachialis origin in 6% and from middle of the medial border of humerus in 3%. While the fourth head originated from the articular capsule of shoulder joint in 1 (1%) limb and from the coracoid process of scapula in the other limb. The biceps common tendon of insertion received the supernumerary heads in 7% of the limbs. However, the extra-head fused with the long head in 2 (2%) limbs and united with the short head in 1 (1%) limb. 
Manoj and co-researchers observed extra heads of BB in
17 upper limbs. They found the three heads of BB in 15 upper limbs (right-9, left-6) and four heads was found in two upper limbs on right side only. 
Poudel and Bhattarai found supernumerary heads of BB in 12.5% of 32 arms. Among these three headed BB was presented on 6.2% and the four headed was also on the same percentage they found the third heads in all cases originated from the medial border and adjoining anteromedial surface of humerus distal to the insertion of CB. Fourth head of the four headed BB originated from the anterior border of humerus nearby the insertion of deltoid muscle.  We also got two similar cases of third head of BB like their study.
Suhani and co-workers found supernumerary heads of BB in 6 (15%) cases. They found three heads of BB in five cases (12.5%) and four heads in one case (2.5%). Out of 5 cases of three heads of BB in 4 cases it took origin from anteromedial surface of humerus distal to the insertion of CB. In addition to this, in two cases they found that it also originated from medial intermuscular septa. In remaining one case, the additional third head was found to be arising from the shaft of the humerus in common with the brachialis muscle. We also got similar two cases in our study like their four cases. In the case where the BB with four heads was observed, its third head was arising from anteromedial surface of the humerus at the junction between the insertion of the CB and the origin of brachialis and its fourth head was from anteromedial surface of humerus distal to the insertion of CB and from medial intermuscular septa.  We didn't get any such case in our study.
But in our study we got one case in which the third head was originating along with the long head of BB and then the third head crosses the musculocutaneous and median nerve in the middle of arm and then finally its tendon goes and insert into the deep fascia of the arm which nobody has got in their study.
These supernumerary heads may be significant in producing the strong flexion as well as supination of forearm. They may be the reason of compression of neurovascular structures because of their close relationship to brachial artery and median nerve. Variant BB may confuse a surgeon who performs operations on the arm and may lead to iatrogenic injuries. The surgeons and traumatologists should be aware of such muscular variations. 
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[Figure 1], [Figure 2], [Figure 3]