Kosugi K, Shibata S, Yamashita H
First Department of Anatomy, School of Medicine, Jikei University, Tokyo, Japan.
Surg Radiol Anat. 1992;14(2):175-85. doi: 10.1007/BF01794898.
Out of 546 upper limbs (273 cadavers), supernumerary heads of the biceps brachii were found in 75 limbs (13.7%) of 58 cadavers (21.3%). The form, origin, and insertion of the supernumerary heads, and branching pattern of the musculocutaneus nerve were studied. In addition, the dimensions of the heads were measured. In many cases, the supernumerary head arose from the humerus, between the insertion of the coracobrachialis and the upper part of the origin of the brachialis, and/or from the medial intermuscular septum. In a few cases, a supernumerary head arose from the tendon of the pectoralis major or the deltoid, or from the articular capsule, or from the crest of the greater tubercle. The supernumerary heads typically joined the common belly, or the aponeurosis of the biceps brachii. Some heads joined the belly of the long head or that of the short head. In the examination of the branching pattern of the musculocutaneus nerve, communication between the musculocutaneus nerve and the median nerve was found in 43 out of the 75 limbs (57.3%). The communicating branch ran from the musculocutaneus nerve to the median nerve in 24, from the median nerve to the musculocutaneus nerve in 12, in both directions in 5, or in another type of pattern in 2 out of 43 limbs. Sometimes a branch of the musculocutaneus nerve ran around a supernumerary head and then fused with the present trunk. The presence of a supernumerary head seemed to affect the course and branching of the musculocutaneus nerve.
在546条上肢（273具尸体）中，58具尸体（21.3%）的75条上肢（13.7%）发现了肱二头肌的额外头。研究了额外头的形态、起点、止点以及肌皮神经的分支模式。此外，还测量了这些头的尺寸。在许多情况下，额外头起自肱骨，位于喙肱肌止点与肱肌起点上部之间，和/或起自内侧肌间隔。少数情况下，额外头起自胸大肌肌腱或三角肌，或起自关节囊，或起自大结节嵴。额外头通常与肱二头肌的总肌腹或腱膜相连。有些头与长头肌腹或短头肌腹相连。在检查肌皮神经的分支模式时，75条上肢中有43条（57.3%）发现肌皮神经与正中神经之间存在交通。在43条上肢中，交通支从肌皮神经至正中神经的有24条，从正中神经至肌皮神经的有12条，双向的有5条，或呈另一种模式的有2条。有时肌皮神经的一个分支绕过一个额外头，然后与主干融合。额外头的存在似乎影响肌皮神经的走行和分支。
