116 THE OSTEOLOGY AND MYOLOGY 



though thus incompletely divisible into two portions, may be in fact only the coracoid, or 

 " short head," which reaches to the margin of the glenoid across the intervening notch, only 

 in consequence of the small size and sessile condition of the coracoid. That part that goes 

 to the glenoid is thick and terete ; the rest is thin and flat. An inch or so below the ori- 

 gin the two parts separate ; these two fleshy bellies do not afterward reunite. The muscle 

 from the flattened coracoid tendon is the larger of the two, and presents externally the 

 appearance of a stout fusiform belly ; but internally it is scooped or fluted, as it were, 

 forming a longitudinal depression in which lies the slenderer, more terete, or spindle-shaped 

 beUy that comes from the glenoid tendon. The large coracoid muscle suddenly diminishes 

 in calibre as it dips down between the pronator radii teres and the extensor bundles on the 

 forearm, and passes to the usual insertion, by a stout rounded tendon, into the tuber radii. 

 The smaller glenoid part accompanies the other into the cleft between the muscles on the 

 forearm ; but it is inserted into the base of the coronoid process of the ulna. I have no 

 idea what useful purpose is subserved by this construction of the chief brachial flexor, but 

 it may convey a hint as to its morphological relations.^ 



Brachialis anticus. — (Fig. 28,^.) The "short" flexor of the forearm does not lie entirely 

 upon the front of the humerus, nor bifurcate above to enclose the apex of the deltoid. It 

 arises from the outer surface of the bone, especially along the slight elevation that marks 

 the upward prolongation of the external condylar ridge, passing obliquely around the inser- 

 tion of the deltoid to gain the front. Fibres take origin from the middle third of the 

 humerus, part of the upper third, and nearly all the broad intercondylar surfice. The 

 muscle dips down between the bundles upon the foi-earm, alongside the tendon of the biceps, 

 to be inserted with the latter into the coronoid process of the ulna. 



Triceps. — (Fig. 28, o, outer humeral, and o', scapular, head.) The single cubital ex- 

 tensor is of great size, and has extensive attachments. It is only incompletely divisible 

 into three heads ; the scapular head alone is perfectly distinct from the others, but repre- 

 senting the middle division of the muscle it serves to partially separate the two humeral 

 portions. This long head arises from the inferior border of the scapula for half an inch or 

 more beyond the glenoid fossa; its fibres at first pass straight dowoiwards, but afterward 

 more obliquely, converging to the common great tendinous intersections. The other two 

 heads, blended together, conjointly take origin from nearly the whole of the posterior 

 aspect of the bone between the brachialis anticus and teres above, and condylar ridges 

 below. There are tendinous laminae in the muscular substance, which separate the scapular 

 from the humeral heads ; but the chief one is that running some distance up the posterior 

 surface of the muscle, as in man. The inner humeral head is the shortest ; it is inserted, 

 together with the scapular, into the olecranon itself; the outer head is longer as well as 



1 This arr.angement of the biceps, which T have verified by triceps, and deriving some fleshy fibres from the lower and 



repeated dissections, differs much from that given by Owen outer third of the humerus. The portion of the biceps aris- 



(Comp. Anat, iii, p. 12) as occurring in another marsupial — ing by the long bead soon resolves itself into two distinct 



the Perameles. This author says: " The bicepx is a powerful penniform muscles; the tendon of the outer one joins that of 



muscle, although its short head from the coracoid process is the brachialis, and this conjoined tendon simply bends the 



suppressed. The long head has the usual origin and relation forearm, while the inner tendon bends and pronates; the 



to the shoulder joint; its tendon is very thick and short. latter, which is a direct, though partial, continuation of the 



The fleshy belly joins that of the strong brachialis internus biceps, is inserted into the ordinary tubercle of the radius; 



[qu. anticus ?] situated at the e.xternal side of the humerus, whereas the outer tendon is attached to the fore part of the 



whence it takes its principal origin from the short deltoid proximal end of the ulna." 

 ridge, closely connected there with the second portion of the 



