632 CIRCULATORY SYSTEM OF THE DOG 



The external iliac lymph glands are small, two or three in number, and lie in 

 front of the circumflex ihac vessels near the point of the hip. 

 The visceral lymph glands of the abdomen comprise: 



1. Gastric lymph glands on the lesser curvature of the stomach. 



2. Several small hepatic lymph glands along the portal vein. 



3. An elongated splenic lymph gland on the splenic vessels near the dorsal end 

 of the spleen. 



4. A series of mesenteric lymph glands situated along the anastomotic arches 

 formed by the vessels of the small intestine. 



5. Several caecal lymph glands situated along the first part of the cscal vessels. 



6. Two series of colic lymph glands which accompany the arteries of the 

 spiral part of the colon, and are exposed l^y separating the coils of the bowel. 

 Small glands are placed in the colic mesentery and above the rectum. 



7. The anal lymph glands are situated on either side on the retractor ani. 



A small ischiatic lymph gland is found on the sacro-sciatic ligament near the 

 lesser sciatic notch. 



The precrural lymph glands are situated on the aponeurosis of the external 

 oblique l)elow the external angle of the ilium. 



The superficial inguinal lymph glands are situated behind the external ingui- 

 nal ring. No deep inguinal lymph glands are present. 



The popliteal lymph glands are small normally and may escape notice. 



A few nodules occur in front of the distal part of the tendo Achillis. 



CIRCULATORY SYSTEM OF THE DOG 

 The Pericardium and Heart 



The pericardium is attached to the sternal part of the diaphragm by a fibrous 

 band, and is connected with the sternum only by the mediastinal pleura. 



The heart is almost globular in form, the apex being much blunter than in the 

 other animals, and marked by a notch. Its long axis is almost parallel with the 

 sternum and the apex (covered by the pericardium) is directed against the sternal 

 part of the diaphragm. Its weight averages about 0.8 to 1 per cent, of the body- 

 weight.^ 



The base extends forward to a transverse plane through the lower ends of the third pair of 

 ribs. The apex lies opposite the sixth costal cartilage in expiration. On the right side the peri- 

 cardium is in direct contact with the chest-wall over a narrow triangular area (base anterior) 

 from the fourth to the sixth intercostal space inclusive. On the left side the area of contact is 

 smaller and is at the fourth, fifth, and sixth cartilages. 



The two coronary arteries may arise by a common trimk. Each divides into 

 circumflex and descending l^ranches. The left artery is twice as large as the right 

 one. 



The great coronary vein ascends in the left longitudinal groove to the cor- 

 onary groove, in which it winds around the posterior face of the heart to the 

 right side and opens into the right atrium below the posterior vena cava. Near its 

 termination it receives one or two veins which ascend along the right longitudinal 

 furrow. Several small veins from the wall of the right ventricle open into the 

 right atrium separately or by a common trunk. 



^ The relative weight is subject to wide variation. It is large in hunting dogs and such as 

 are trained for speed or worked. 



