66 
and, one of them, perhaps into the bone above it. There is a normal 
triceps; and an extra one which receives fibres from the first. The 
extra one runs to the inverted olecranon and to the extra internal 
condyle. 
In the forearm the muscles usually connected with the radius 
and thumb are of course wanting. The superficial flexor of the fingers 
arises from the inner condyle corresponding to the perfect ulna; and 
sends a tendon to each finger, excepting the little finger of the im- 
perfect side (i. e. of the extra hand), also a slip from the tendon of 
the index finger to the deep-seated tendon of the same. The deep 
flexor arises in two parts. That for the normal hand arises chiefly 
from the normal ulna, partly from the interosseous membrane. The 
portion for the index has its muscular belly to a great extent separate 
from the rest. The part for the extra fingers arises almost if not 
quite exclusively from the inverted ulna. The little finger has only 
a small slip given off from the side of the tendon to the ring finger. 
The common extensors of the fingers may be described as follows: 
A fleshly mass arises from the outer side of the normal olecranon, 
between it and, the fused outer condyles, which sends extensor tendons 
to the four normal fingers. The one to the index is very small and 
soon separates from the others. There are the usual cross connections 
over the metacarpus between the tendons of the inner three fingers. 
An Extensor proprius indicis arises from the middle of the ulna and 
the interosseous membrane. The extensor of the extra hand arises 
partly in common with the other from the fused outer condyles and 
partly from the region of the inverted olecranon. It sends tendons, 
more or less fused, to the three extra digits and a small slip to the 
index of the normal hand which joins near its insertion the tendon 
of the Extensor proprius indicis already mentioned. There arises also 
from. the back of the inverted ulna and perhaps from the interosseous 
membrane a second Extensor proprius indicis which is very much the 
largest of the four extensor tendons going to that finger. The next 
largest is the Extensor proprius of the normal hand. 
The Arteries. The brachial divides at about the junction of 
the middle and lower thirds of the humerus. The main continuation, 
which is the ulnar proper, runs deeply under a band thought to re- 
present the Pronator radii teres, to the deep part of the forearm 
where it gives off the interosseous. Above the elbow there is a branch 
running backward between the internal condyle and the olecranon. 
The interosseous branches are not easy to trace. There seems to be 
an anterior interosseous and three branches on the back of the fore- 
