30 
PRIMROSE : THE ANATOMY OF THE ORANG OUTANG 
the anthropoid apes; in Huxley’s Gorilla^ it was only represented by 
a ligament 
The Triceps muscle had the following origin : — i. The long head 
arose from the upper two-thirds of the axillary border of the scapula 
to the extent of 4 cm.. The upper part of its origin being in front of 
the teres minor and the lower part behind the teres major. 2. The 
inner head arose from the posterior aspect of the humerus a short dis- 
tance above and behind the lowest point of attachment of the teres 
major. The musculo-spiral nerve crosses this head obliquely about 
2.5 cm. below its upper limit ; the nerve is thus separated from the 
bone by the muscle. 3. The external head arose from the posterior 
aspect of the humerus as high up as the insertion of the teres minor. 
The musculo-spiral nerve proceeds outwards between the lower part of 
this muscle and the bone. The triceps possesses a very wide fascial 
insertion in the region of the elbow, and is inserted also into the 
olecranon process. Fick remarks upon the striking weakness of the 
inner head in his Orang. 
The Coraco-brachialis arose from the anterior portion of the coracoid 
process, and from the fascia over the subscapularis muscle ; two por- 
tions of the muscle were defined, one found insertion by an attachment 
2.5 cm. wide into the middle of the inner portion of the humerus, whilst 
a more feebly developed upper portion found an attachment by an 
insertion 0.5 cm. wide immediately above the other portion. The two 
parts are separated by the passage of the musculo-cutaneous nerve, 
which sends a branch of nerve supply to each. Some fibres from the 
upper portion pass down in front of the tendinous insertion of the lower 
part, and there find independent insertion into the humerus. Wood by 
a comparative study of this muscle in the mammalia concludes that 
the coraco-brachialis is made up of three component parts : i. The 
coraco-brachialis brevis, which passes from the outer side of the coracoid 
process near its root, to the capsule of the shoulder-joint near the ana- 
tomical neck of the humerus ; 2. The Coraco-brachialis medius obtaining 
its insertion into the inner border of the humerus near its middle ; 3. The 
Coraco-brachialis longus, which extends down the inner side of the arm 
to be attached to the internal condyle. The coraco-brachialis medius 
is the portion of the muscle which is characteristically of human type; in 
man also, both brevis and longus occur as varieties, the latter being the 
1 Loc. cit.. Vol. I, p. 538. 
2 John Wood, “On Human Muscular Variations, and their Relation to Comparative Anatomy. 
Journ. of Anat. and Phys., Vol. I, 1867, p, 45. 
