vr / /-;> or /'///; TRUNK. -:::. 



tractcd at its two extremities, situated in front of the preceding, arising 

 from the sternum, dinvtnl forwards and outwards towards the scapulo- 

 liiimcral angle, and afterwards reflected upwards and backwards on the 

 anterior border of the shoulder, which it follows to near the cervical angle 

 of the scapula. 



Structure and Attachments. J.t is formed of very large fleshy fasciculi, 

 analogous to those of the sterno-trochineus, which originate, by their 

 inferior extremities, from the sides of the sternal keel and the cartilages of 

 the first three or four ribs. They follow the direction of the muscle, and 

 terminate, one above the other, on a short aponeurosis which covers the 

 supraspinatus, and is confounded with the external aponeurosis of the 

 scapula (Fig. 114, 14). 



fiaiotiOM. In its axillary portion, this muscle responds, inwardly, to 

 the costo-sternalis, the first sternal cartilages, and the corresponding inter- 

 costal muscles : outwards, to the sterno-trochineus and sterno-aponeuroticus. 

 In its prescapular portion, it is in relation, outwardly, with the mastoido- 

 humeralis and trapezius ; inwardly, with the subscapulo-hyoideus, the 

 scalenus, and the angularis of the scapula ; behind, with the supraspinatus 

 which is separated from it by the external scapular aponeurosis. 



Action. This muscle is a congener of the sterno-trochineus, and pulls 

 the scapula backwards and downwards. It is also a tensor of the scapular 

 apoueurosis. 



DIFFERENTIAL CHARACTERS OF THE MUSCLES OF THE AXILLARY REGION IN OTHER 

 THAN SOLIl'ED AM1IALS. 



With regard to the superficial pectoral, it is remarked that in the Ox, Sheep, and 

 I'i'i. the sterno-humeialis is .-mull and less distinct from the sterno apc>ncuroticu8 than in 

 Solipeds ; and that in the Dog and Cat, the sterno-aponeuroticus is very thin aud 

 narrow. 



In the deep ]>ectorul there is found, in the Ox, a sterno-prescapularis scarcely distinct 

 from the sterno-trochineus, and which does not extend beyond the inferior extremity of 

 the supraspinntus. In the toheep, this muscle is quite confounded with the sterno- 

 trochineii-. In tin- I'ig, the sterno-prescapulnris somewhat resembles thnt of the II 

 Its inferior extremity only covers the first chondro-sternal articulation; tlie superior 

 fxtr. mity is more voluminous. With reir.irl t<> the stcriio-trochincus. it terminates on 

 iniiiit i if the irr. nt trochanter, after detaching a short branch t< the tendon of the 

 coraco-humeralis. Tlie sterno-prescapularin of the ]><xj i.s very t' eUe, and terminates 

 with the principal muscle on the l.umerus. 



COSTAL REGION. 



In each costal region wo find fifty-four muscles, which concur, more or 



less directly, in the respiratory movements. These muscles are : 1, The 



great serratm ; 2, The costo-transveraalit ; 3, Seventeen external intercostal* ; 



4, Seventeen internal intercostal* ; 5, Seventeen gupercostals ; 6, The 



'lularis sti'rni. 



Preparation. 1. Place the subject in the second poiti<ii). '1. Uem.-ve tlie fore- 

 l' and all tlie muscled attaching it to the trunk, by .-aw inn through the scapula aa 

 shown in figure in.", in order to expose the great serrattis and cotdo-traiiBVcrsalis muscl. s ; 



linMi tlj. .1: tinu of this forrm-r by taking awuy all the yellow fibrous tissue which 



covers its posterior dt-ntatinns. !J. Study the external intercostals and the superoostals, 



removing tip -real -ililiiiue muscle of the alxlomen. the s.-rmti miiHclca, the 



common inteii-".-tal (ilio-costalis), and the ilio-spinalis. I MM-J-- f .>m- \i.-rnal inter 



cotals in order to hlmw the corresponding internal on,-. .">. The tiianguluris it. 



1 on another |Mirt:oiL, which is obtained in separating the .stennim from the 

 by aawing through tl,. -hi mil ribs a little above their inferior extremity. 



