236 ANATOMICAL TECBNOLOGY. 



by means of the pectoral muscles is twice as great in the cat as in man. This will hardly 

 surprise those who have watched a kitten at play, or a cat in any kind of vigorous action. 

 It must be remembered, however, that this superior complexity of the muscles acting- upon 

 the brachium, and thus upon the limb as a whole, does not confer peculiar powers upou 

 the distal segment, and no one would regard the cat's manus as equal to that of man. In 

 the quadruped, the specialization is proximal and the distal parts are relatively simple ; 

 with the bimanous biped, the muscles acting upon the arm as a whole are 'comparatively 

 simple and in what may be regarded as a generalized condition, but the projection of the 

 brachium from the thorax confers great freedom of movement, while the distal muscles 

 are more distinct and independent than in the cat. 



Those who are disturbed that any parts of a cat should be described as more complex 

 than the corresponding human organs should compare the stomach and brain of man with 

 the same parts of the pig, sheep and porpoise. 



§ 643. Caution. — Excepting the muscles especially related to 

 the vertebral column, there are probably none more difficult of dis- 

 section than the pectorales. This is due in part to the number and 

 extent of the individual variations which have so far made it impos- 

 sible to provide directions to meet all cases, but chiefly to the 

 intrinsic complexity of superposition and attachment. 



The student should proceed with great caution, follow the direc- 

 tions and descriptions as closely as possible, repeat the dissection 

 upon the opposite side, and make careful notes and drawings of all 

 peculiarities. 



§ 644. ExposTire. — As with the trapezius group, it is usually 

 more convenient to expose all of the pectorales by lifting a single 

 flap of skin. 



Connect the antebrachial end of the incision made in exposing 

 the clavo-deltoideus with the free border of skin left in exposing the 

 dermo-humeralis and latissimus, or with the epigastrium (Fig. 72). 

 Begin with the skin already raised from the ventral aspect of the 

 brachium, and reflect the flap just circumscribed across the ventri- 

 meson. To cut as nearly as possible in the direction of the fibers, 

 the flap may be grasped at first by the angle near the shoulder, but 

 later by its caudal margin. Great care must be taken to avoid 

 injuring the subjacent muscles. 



M. PECTO-ANTEBRACHIALIS. 



§ 645. Synonymy. — " Peeto-antebrachial" S.-D., A, II, 353 ; " sterno-aponeurotique," 

 Ch., A, 347 ; steriio-aponevroticus, Ch. (Fl.), A, 333 ; part of " pectoralis, part 1" Mi v., B, 

 145 ; not normally represented in man. 



Figures. — Ectal aspect of both divisions (73, right side ; distal ends (73, left side). 



General Description. — In two divisions, cephalic and caudal, 

 from the viedian raphe at the prmsternum and 3d mesosterneier 



