MUSCLES OF THE THORAX — MUSCLES OF THE BACK AND LOINS 361 



The intertransversales resemble those of the ox. 



The splenius is thick and extensive. It ends in three parts on the occipital, 

 the temporal, and the wing of the atlas (inconstant). , 



The longissimus capitis et atlantis is small, and its atlantal part is blended 

 with the longissimus cervicis. 



The complexus is large, and is clearly divided into two parts: the dorsal part 

 (Biventer cervicis) is marked by several tendinous intersections; the ventral part 

 is the complexus proper. 



The obliquus capitis posterior is relatively thin. 



The recti capitis dorsales are thick and more or less fused. 



Muscles of the Thorax 



The levatores costariim and rectus thoracis present no special features. 



The external intercostal muscles are absent under the serratus dorsalis and the 

 digitations of the external oblique. 



The internal intercostals are thick between the cartilages of the sternal ril)s. 



The retractor costse and the transversus thoracis resemble those of the horse ; 

 the latter extends back to the eighth cartilage and fuses with the transversus ab- 

 dominis. 



The diaphragm has seven costal digitations on each side, the posterior ones 

 being attached to the ribs at some distance (ca. one-third to one-fourth of rib- 

 length) from the costo-chondral junction.' The line of attachment reaches the 

 latter at the tenth rib, and passes along the eighth cartilage to the xiphoid process. 

 The tendinous center is more rounded than in the horse. The crura are well 

 developed. The right crus is very large, and is perforated by the extensive slit- 

 like hiatus cesophageus, which is median in position, and lies about two and one- 

 half to three inches (ca. 6 to 8 cm.) below the twelfth thoracic vertebra. The hiatus 

 aorticus is between the crura. 



Abdominal Muscles 



The abdominal tunic is little developed. 



The obliquus abdominis extemus has an extensive fleshy portion and a cor- 

 responcUngly narrow aponeurosis; the latter does not detach a femoral lamina, 

 but is reflected in toto to form the inguinal ligament. 



The obliquus abdominis intemus resembles that of the ox; a small fusiform 

 muscle, which crosses the inguinal canal obliquely and is attached on the abdominal 

 surface of the inguinal ligament, is apparently a detached slip of the internal 

 obUque. 



The rectus abdominis is extensive and thick. It has seven to ten inscriptions. 

 Its tendon of insertion fuses largely with the common tendon of the graciles, and 

 does not give off an accessory band to the head of the femur. 



The fleshy part of the transversus abdominis is well developed. It blends 

 in front with the transversus thoracis. 



The cremaster extemus is present in the female as well as in the male. 



Muscles of the Back and Loins 



The serratus dorsalis anterior is inserted into the fifth to the eighth ribs 

 inclusive, the serratus dorsalis posterior into the last four or five ribs. There are 

 usually no digitations attached to the ninth and tenth ribs. 



1 It is interesting to note that the diaphragm has no attachment to the fifteenth rib, which is 

 often present and well developed. 



