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 costarum 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 ribs. 
The retractor coste 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 em.) below the twelfth thoracic vertebra. The hiatus 
aorticus is between the crura. 
ABDOMINAL MUSCLES 
The abdominal tunic is little developed. 
The obliquus abdominis externus has an extensive fleshy portion and a cor- 
respondingly narrow aponeurosis; the latter does not detach a femoral lamina, 
but is reflected in toto to form the inguinal ligament. 
The obliquus abdominis internus 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 
oblique. 
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 externus 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 Tt is interesting to note that the diaphragm has no attachment to the fifteenth rib, which is 
often present and well developed. 
