EXAMINATION OF SOME SPINAL NERVES 83 
deep short muscles of the thumb, 
short muscles of little finger. 
1st, 2nd and 3rd lumbricales. 
all the palmar -j c The amount of degeneration was greater in the IVth 
„ , , , - interossei . " , • ■ "t 
all the dorsal j I palmar mterosseus than in the 1st. 
In this experiment 73 degenerate fibres were present in the cervical sympathetic — fine 
myelinate all of them. 
After this motor root has been destroyed by degeneration, a considerable number of 
perfectly sound nerve-fibres still persist in the first intercostal nerve. Tiiis latter must therefore 
contain a number of afferent nerve-fibres, although in the Monkey it does not give any lateral or 
other cutaneous branch — at least I have found none. In the same way the small dorsal primary 
division of this nerve is found to contain a number of fibres from the spinal root-ganglion, although 
it gives off no cutaneous branch. TIic motor fibres in the small posterior primary division innervate 
the erector spin^ej levator costte^ and transverso-spinales. 
Xth Nerve or IInd Thoracic Nerve 
I. Sensory Root. Distribution to Skin. 
Example. — M. rhesus. 9. At 10 a.m. the posterior roots of the llird, IVth, Vth, Vlth, 
Vllth, and Vlllth cervical, and of the 1st, Ilird, IVth, and Vth thoracic nerves of the right side 
severed ; at 5 p.m. the skin-field of Ilnd thoracic nerve finally delimited. 
' The isolated field of response is limited by a line which runs as follows : — It starts at a 
point one-third down the forearm, at tlie junction of the ulnar and flexor surfaces : it from there 
slopes upward across the root of the olecranon, and along the space between olecranon and inner 
condyle. It passes up the upper arm along the middle of the posterior aspect of it, on the surface 
of the triceps behind the biceps, and close beliind the deltoid muscle. It meets tiie spine of the 
scapula near its acromial end, and at once returns to sweep into axilla and recurve upward once 
more and wind the pectoral fold to the front of the chest on pectoralis. It then retires again, and 
comes down the outer aspect of the arm. It passes just in front of the outer condyle of the 
humerus, and down the extensor face of the forearm, sloping towards the head of the ulna, and 
above that recurves, to pass upwards and attain the point whence it was originally traced. It 
therefore reaches a little more than half way down the forearm, and approaches the wrist most 
nearly in the skin over the ulnar border of the forearm.' 
2. Motor Root. IInd Thoracic Nerve. [See Conspectus, p. 114, infra.) 
I have never, in Macacus, found wanting a distinct contribution from the IInd thoracic 
to the brachial plexus. I ascertained by degeneration experiinents that this, which is too short to 
stimulate without some risk of escape of current, contains both motor and sensory fibres. In full 
accord with the distribution of the degeneration, excitation of the IInd thoracic motor root gives 
contraction of a number of liand muscles. W. Krause, although he noted the presence of this 
branch in tlie Rabbit, did not discover it^ importance to the plexus. Forc;i'K and Lannegrace 
