254 TRANSACTIONS OF THE [MAY 13, 
II. RELATION OF BICEPS TO THE ADJOINING DEEP VENTRO-APPENDIC- 
ULAR FIBRES OF THE CORACO-BRACHIALIS, AND, III, TO THE 
DEEP INTRINSIC FLEXOR OF FOREARM, BRACHIALIS 
ANTICUS. 
The consideration of the variations, described above as the 
Humero-uJnar internal head and the Coraco-epitrochlear slips, in- 
dicate the intimate relation existing between the Biceps and the 
Brachialis anticus and Coraco-brachialis. 
Humphry, * in describing the muscles of the Cryptobranch, 
accentuates the close relation of the Coraco-brachialis longus 
and Biceps of this animal. He finds that the former muscle 
divides into two portions, one of which is inserted into the 
ulnar edge of the humerus; the other, being nearly as large, is 
partly inserted into the side of the long tendon of the Biceps, 
while a bundle of its fibres continues over the elbow and is in- 
serted into the ulna near the joint. Humphry regards this lat- 
ter portion as the representative of the short or coracoid bicip- 
ital origin in man. 
We find in this instance on the one hand the direct union of 
the Coraco-brachialis with the Biceps, and on the other insertion 
of part of the muscle into the ulna. 
Again the Brachialis anticus is in some forms (Pteropus) 
found to be in direct continuity with the Coraco-humeral, + and 
in the Scine the Biceps derives two factors from the humerus, 
which occupy the position of the Brachialis anticus and are so 
named by Rudinger. Humphry sums the mutual relations of 
these three muscles up as follows : 
“They show the Biceps to be an intermediate between the 
Coraco-humerals and Brachialis anticus, continuous with either 
or both, and uniting them into one group, extending from the 
coracoid, along the ulnar and palmar surface a the humerus, 
to the radius and ulna.” 
I believe that we may properly regard the variations of the 
Biceps above referred to in this light. Both the Coraco-epi- 
trochlear slips and the Internal humeral heads speak for the 
original unity of a muscular plane extending between coracoid 
and ulna. 
The separation of the radius as the rotatory element of the 
forearm and hand, and the assignment of the corresponding 
muscular function to the Biceps, have caused the elimination of 
the ulnar segment of the muscle, leaving the Brachialis anticus 
as the deep intrinsic flexor connected with the ulna, and reduc- 
* Op. cit., p. 33. 
+ Humpbry, op. cit., p. 164. 
