Koizumi M, Sakai T
Department of Anatomy, Juntendo University School of Medicine, Tokyo, Japan.
J Anat. 1995 Apr;186 ( Pt 2)(Pt 2):395-403.
The origin of the nerve supply to coracobrachialis from the brachial plexus in apes was investigated in 4 arms from 4 chimpanzees, both arms of a gorilla and 4 arms from 4 gibbons. The general architecture of the brachial plexus was the same as in the human. In the apes examined, the nerves supplying this muscle could be classified into 2 groups: (1) distal branches arising from the musculocutaneous nerve, and (2) proximal branches arising in the region of the lateral cord. On the basis of their origin and course, the proximal branches were classified into 3 types, namely a deep ramus arising from the middle trunk and passing dorsal to the upper trunk, a medial ramus arising from the upper trunk in the lateral cord, and a superficial ramus arising from the ventral surface of the middle trunk or the root of the pectoral nerve. This classification also applies to branches to coracobrachialis in man. The 3 types of proximal branch often communicated with each other to supply coracobrachialis, whereas the proximal and distal branches were separated from each other spatially. This indicates that coracobrachialis possesses characteristics both of the pectoral girdle muscles and the flexor muscles of the upper arm.
对4只黑猩猩的4条上肢、1只大猩猩的双臂以及4只长臂猿的4条上肢进行了研究，以探究猿类臂丛神经对肱二头肌的神经支配起源。臂丛神经的总体结构与人类相同。在所检查的猿类中，支配该肌肉的神经可分为两组：（1）发自肌皮神经的远端分支，以及（2）发自外侧束区域的近端分支。根据其起源和走行，近端分支可分为3种类型，即发自中间干并从背侧穿过上干的深支、发自外侧束中上干的内侧支以及发自中间干腹侧表面或胸神经根部的浅支。这种分类也适用于人类肱二头肌的分支。3种近端分支经常相互连通以支配肱二头肌，而近端和远端分支在空间上相互分离。这表明肱二头肌兼具胸带肌和上臂屈肌的特征。
