PRIMROSE : THE ANATOMY OF THE ORANG OUTANG 
31 
more common. Vrolik^ describes the medius and longus as existing in 
the Chimpanzee, a condition which also existed in Hepburn’s Orang. 
The degree of development of this muscle is, however, by no means 
constant, but, according to Bischoff, numerous variations occur both 
among the anthropoid apes and among the lower apes. In certain of the 
mammalia, according to Wood, the brevis alone is developed as in the 
dog and cat, also in bats and moles. Bland Sutton^ compares the 
arrangement of the coraco brachialis in its three parts in the arm to 
the arrangement of the three adductor muscles in the thigh. 
The Biceps resembled, in its two heads of origin, the condition found 
in man ; it was inserted into the radius by an aponeurosis of insertion 
1.5 cm. wide, very thin and ribbon-like as it passed back into its inser- 
tion, which lay wrapped around the neck of the radius when the forearm 
was pronated. A well-developed bicipital fascia passed off to blend 
with the fascia on the inner border of the forearm. This fascia was 
absent in Pick’s Orang. BischofT states that in all apes (anthropoids 
and others) the biceps arises as in man, with the exception of the Gibbon, 
where he found that the short head arose from the lesser tuberosity of 
the humerus instead of from the coracoid process ; Huxley^ found in 
his Gibbon, the short head arising from the tendon of the pectoralis. 
major. The muscle is subject to great variation in man chiefly in the 
multiplication of additional heads of origin : the long head has 
occasionally been absent, as described by Lubosch® and others in 
man, but such a defect is extremely rare. 
The Brachialis anticus arose from the anterior portion of the humerus 
as high up as the insertion of the deltoid, the origin of the muscle being 
wholly external to the insertion of the coraco brachialis. It was inserted 
into the coronoid process of the ulna. A narrow slip from the outer 
aspect of this muscle crossed in front of the musculo spiral nerve and 
joined the supinator longus. This connection with the supinator longus 
has been observed in man (Testut). 
The Pronator radii teres arose by two heads, one from the internal 
condyle and the intermuscular septum, and the other from the coronoid 
process of the ulna on its inner aspect. The median nerve passed into 
I Loc. cit., p. 30. 
2 . Loc. cit.. p. 13. 
3 Loc. cit. I, p. 210, 
4 Loc, cit,, Vol. I, p. 648. 
5 W, Lubosch. “Ein M, Coraco — Antibrachialis beim Menschen Beitrage zur Morphologic des M, 
Biceps Brachii.” Morphologisches Jahrbuch, Bd. XXVII, Heft 2, 1899, p, 309. 
