Poudel P P, Bhattarai C
Department of Anatomy, Manipal College of Medical Sciences, Pokhara, Nepal.
Nepal Med Coll J. 2009 Jun;11(2):96-8.
Biceps brachii is a double headed muscle. In terms of number and morphology of its head, it is one of the most variable muscles in the human body. Most common variation is third head, but four, five or even seven heads have been reported. In this study, 32 arms from 16 Nepalese cadavers were studied; supernumerary heads of biceps brachii were observed in 12.5% of 32 arms. Among these three headed biceps brachii was presented on 6.2% and the four headed was also on the same percentage. All the variations were in the right sided arms of males. Third heads of all cases originated from the medial border and adjoining anteromedial surface of humerus distal to the insertion of coracobrachialis thus have been classified as inferomedial humeral head. Fourth head of the four headed biceps brachii originated from the anterior border of humerus nearby the insertion of deltoid muscle. These supernumerary heads might be significant in producing the strong flexion as well as supination of forearm. They may cause compression of neurovascular structures because of their close relationship to brachial artery and median nerve. Variant biceps brachii may confuse a surgeon who performs procedures on the arm and may lead to iatrogenic injuries. The surgeons and traumatologists have to keep such muscular variations in mind.
肱二头肌是一块双头肌肉。就其头的数量和形态而言，它是人体中变异最多的肌肉之一。最常见的变异是出现第三个头，但也有报道称出现四个、五个甚至七个头的情况。在本研究中，对来自16具尼泊尔尸体的32条手臂进行了研究；在32条手臂中，有12.5%观察到肱二头肌有多余的头。其中三头肱二头肌出现的比例为6.2%，四头肱二头肌出现的比例也为6.2%。所有变异均出现在男性的右侧手臂。所有病例的第三个头均起源于肱肌插入点远端的肱骨内侧缘及相邻的前内侧表面，因此被归类为肱骨内下头。四头肱二头肌的第四个头起源于靠近三角肌插入点的肱骨前缘。这些多余的头在产生前臂强有力的屈曲和旋后方面可能具有重要意义。由于它们与肱动脉和正中神经关系密切，可能会导致神经血管结构受压。变异的肱二头肌可能会使对手臂进行手术的外科医生感到困惑，并可能导致医源性损伤。外科医生和创伤科医生必须牢记这种肌肉变异情况。
