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Variations in the Biceps Brachii in North Bengal - An Observational Study

BACKGROUND Supernumerary heads of the biceps brachii are a common anatomical variation, with an incidence of 3.7 % to 20.5 % in various studies carried out around the world. They can occur in various forms, and produce a range of clinical symptoms, such as impingement syndromes at the shoulder joint, and nerve-compression syndromes in the arm. An awareness of these variations is helpful when assessing patients with pain symptoms in the region of the shoulder and arm. The purpose of this study was to examine the morphology, nerve supply, and variations in morphology, of the biceps brachii in a population in Eastern India. METHODS This observational study was carried out on 20 (17 males, 3 females) formalinembalmed cadavers during routine gross anatomy dissection of the upper limb, using standard dissection methods. We examined the morphology, nerve supply, and variations in morphology, of the biceps brachii in a population in Eastern India. RESULTS Three upper limbs (7.5 % out of 40 limbs) showed supernumerary heads. In one male, a third humeral head of origin, from the anteromedial surface of the shaft of the humerus was observed in the left upper limb. In another male cadaver, we found a unique case with bilateral third heads with an aponeurotic origin from the capsule of the shoulder joint, with the third head comparable in size and bulk to the long and short heads. The remaining upper limbs showed the usual morphology, with the long head originating intracapsularly from the supraglenoid tubercle of the humerus and the glenoid labrum, and the short head from the tip of the coracoid process of the scapula. Insertions were usual. CONCLUSIONS Our study found an incidence of 7.5 % in a population sample from Eastern India, North Bengal. Supernumerary heads can occur in various forms, and can result in varied clinical symptoms. KEYWORDS Biceps Brachii, Biceps Brachii Variations, Supernumerary Head, Third Head, Humeral Head, Long Head of Biceps