An anatomical study on the three-headed biceps brachii in human foetuses, and clinical relevance

Abstract

The biceps brachii (BB) is as one of the most variable muscles in the human body in terms of number and morphology of its heads. The most frequent variation is the presence of a third head, which has been reported by several authors in different populations. Our aim was to find the occurrence of the supernumerary head of BB in Turkish foetuses. Out of the 24 upper limbs of the foetuses, two (8.33%) arms were found to have a three-headed BB. The variations were present unilaterally in the right arm of one male foetus and one female foetus. In one of the cases, the third head of BB originated from the anteromedial aspect of the humerus just distal to the insertion of the coracobrachilais, medial to the brachialis, and in the other the third head was a thin muscle bundle, which arose on the lateral side of the insertion of coracobrachialis and over the origin of the brachialis. Both of them were extended distally and joined the common tendon. The occasional presence of the three-headed BB in the foetuses observed in the present study was similar to those of adults reported in previous studies. In conclusion, these variations are not rare and are interesting not only to anatomists but also to orthopaedic surgeons, plastic surgeons, traumatologists, physiotherapists, doctors dealing with sports medicine, and radiologists. (Folia Morphol 2011; 70, 2: 116–120)