r l he Minute Anatomy of the Brachial Plexus. 441 



Eadial 



5 and 6 <f -^ e ^ ^ ^ rom scapula. Supinator longus. Extensores carpi 

 1 radiales. 



y f Latissimus dorsi. Teres major. Triceps. Extensores carpi 

 \ radiales. Extensors slightly. 

 8 and 9 . . Latissimus dorsi. Triceps. Extensors. 



Cubital.f 



Flexor profundus. Flexor carpi ulnaris. Intrinsic muscles of hand. 

 He lays down also the following laws : — J 



1. Each root furnishes branches to two systems, an anterior and a 



posterior. § 



2. As the stimulus approaches the dorsal pairs, the contraction 



occurs in lower segments of the limb. 



3. As the stimulus approaches the dorsal pairs, the contractions 



pass from the radial to the ulnar border. 

 He also adds — 



"It is a secondary law that the superficial layers are supplied 

 before the deep." 



Both these observers worked with monkeys, and Forgue's laws are, 

 with the exception of the first, identical with those which human 

 dissections have produced for me. That the details should exactly 

 correspond is not to be expected in two different genera when indi- 

 viduals of the same vary so widely. 



Electrical stimulation does not show the sensory supply. 



I have often tried to complete this account by dissecting the nerves 

 upwards to the spinal cord. I have, however, never been able to rely 

 on the results. The connective tissue permeating the nerve separates 

 and protects the bundles of nerve fibres composing it, and renders their 

 dissociation impossible. But as the nerve nears the intervertebral 

 foramen this tissue A^ery rapidly diminishes, and in the foramen the 

 root consists of nerve bundles with hardly any connective tissue 

 between them. The nerve bundles in the adult might perhaps be 

 separated even here from one another, but in the foetus, and these 

 alone are for this purpose accessible to me, their minuteness and their 

 softness have prevented any satisfactory dissection. 



* The radial here means the posterior cord of the plexus, 

 f Ulnar. 

 t Pp. 41-43. 



§ This refers to the adult position. A truer view is to take the earliest observed 

 position in the foetus. 



