THE VASCULAR SYSTEM 253 



cloacal gland. The cloacal sinus has two communications with the 

 vesicular sinus surrounding the base of the bladder, namely, one 

 mesial, close to the middle line, and one lateral, passing in company 

 with the pudendal vessels and nerve, which may accordingly be 

 termed the -pudendal trunk. Anteriorly the cloacal sinus is continued 

 as the pelvic sinuses. 



The pelvic sinuses (s.ly.pel.) lie on either side of the middle line 

 beneath the pelvis, and consist of a very coarse and irregular network 

 with small meshes. They drain the sub-pelvic network, and, in part, 

 the cloacal sinuses, and finally enter the inguinal sinuses at their 

 antero-mesial angles. A small vessel may usually be traced leaving 

 the anterior extremity of the pelvic sinuses and passing along the 

 lateral edges of the ypsiloid cartilage to join the para-epigastric 

 trunks. The sinuses of either side communicate with one another 

 by several small vessels. 



The inguinal sinuses (s.ly.ing.) (sinus inguinales, of the German 

 authors) lie lateral to the sinuses just described within the 'groin', and 

 are really the ventral portion of a continuous sinus surrounding the 

 base of the limb, the dorsal portion being known as the iliac sinus. 

 After joining with the pelvic sinus anteriorly each inguinal sinus 

 sends a trunk around the anterior and dorsal aspects of the limb 

 which accompanies the V. iliaca transversa. This trunk receives the 

 pre-axial trunk from the leg, and communicates freely with the sub- 

 cutaneous network covering the ilium as well as with the iliac sinus. 



The iliac sinus (s. ly.il.) is a rather irregular sac lying at the posterior 

 aspect of the leg immediately behind the ilium. It stands at the 

 junction of several large sinuses which meet in that region, namely, 

 the post-axial trunk from the hind-limb, the inguinal sinus, and the 

 vesicular sinus from the bladder. It also communicates freely with 

 the subcutaneous network overlying it, and by means of this network 

 a fair proportion of the lymph from the iliac region enters the lateral 

 lymph hearts of the tail and is discharged by them into the V. 

 lateralis (see p. 232). The rest of the lymph passes through the 

 truncus iliacus accompanying the iliac artery and vein, to enter the 

 subvertebral trunk. 



All sinuses so far described are superficial to the muscles and 

 skeleton. Immediately dorsal to the pubo-ischium, between it and 

 the bladder, lies the vesicular sinus (s.ly.ves.). It is hammock-shaped 

 and covers the ventral side of the neck of the bladder, and, as already 

 mentioned, it communicates ventrally with the cloacal sinus, laterally 

 with the iliac sinuses, while dorsally near its posterior margin it 

 enters the peri-anal sinus. 



