DE. GENTHEE ON THE ANATOMY OE HATTEEIA. 
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and terminates in a tendon attached to the outer convex surface of the end of the 
humerus, immediately above the insertion of the M. brachialis internus. This muscle 
assists materially in drawing the limb forward. 
The M. biceps brachii is situated as in higher animals, but divided into two distinct 
muscles running parallel to each other, being separated superiorly only by the insertion 
of the pectoralis major : the inner muscle (corresponding to the the caput breve of human 
myology) is the longer, indeed the longest muscle of the arm, extending from the sternal 
margin of the coracoid to the upper end of the ulna ; above its middle, where it is crossed 
by the tendon of the pectoralis major, it is reduced to a narrow tendon, so that there is 
no friction between the two muscles although they cross each other ; it is fleshy again 
towards the margin of the coracoid. The outer muscle, fixed to the upper end of the 
radius, is arrested in its course by the tuberculum majus humeri, to which it is attached 
by the side of the pectoralis major; a strong ligament running from this tubercle to the 
scapula may be regarded as the continuation of the tendon of this muscle, and as homo- 
logous with the “ caput longum .” 
A very slender muscle accompanies this part of the M. biceps ; and being also attached 
to the upper end of the radius, and passing uninterruptedly into the ligament described 
as homologous with the “ corpus longum,” it may properly be taken as a third detached 
part of the biceps. 
The M. coraco-brachialis has, in accordance with the development of the coracoid bone, 
become a very powerful muscle ; it may be incompletely divided into two portions, the 
anterior of which is broad, flat, arising nearly from the entire surface of the bone, and 
inserted all over the concave surface of the end of the humerus, downwards to the middle 
of its length, where it is confluent with the inferior portion ; this is a more slender 
muscle, taking its origin from the lower posterior angle of the coracoid, and inserted at 
the condylus extemus humeri. The function of the entire muscle is to depress the limb, 
and to effect a simultaneous rotatory movement of its longitudinal axis. 
The M. brachialis internus is well developed, and does not essentially differ from that 
of Emys or of Mammalia. 
The M. triceps is very peculiar ; it consists of two strong portions, an inner and a 
superficial, both confluent with each other and with the M. brachialis internus near the 
olecranon : the inner portion is attached along the body of the humerus between olecra- 
non and tuberculum minus. The superficial stronger portion passes between the tendi- 
nous ends of the Latissimus dorsi and Deltoides, and is inserted into the contracted part 
of the scapula ; however, before it passes the tendon of the Latissimus dorsi, it emits 
another, long, slender tendon, crossing the plexus nervorum brachialis and attaching 
itself to the inside of the posterior angle of the coracoid. This tendon appears to serve 
merely as an additional point of attachment to the muscle. 
Muscles of the lower arm. — The flexor muscles arise chiefly from the inner condyle of the 
humerus and the inner surface of the bones of the lower arm. Their number is reduced 
to three, viz. : — First, the M. flexor digitorum profundus, terminating in five tendons for the 
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