238 LABORATORY MANUAL FOR VERTEBRATE ANATOMY 



injured in the dissection of the renal portal system, try the other side.) It run 

 laterally to the point where the renal portal vein enters the pleuroperitonea 

 cavity. At this point it divides. The anterior branch continues to the carapao 

 and runs forward along the curve of the carapace, supplying the fat bodies an< 

 becoming continuous with the margino-costal artery described above. Thi 

 posterior branch turns and passes medially parallel to the ventral abdomina 

 vein. It supplies the base of the leg and the pelvic muscles and terminates 01 

 the ventral surface of the pelvis. 



Next follow the common iliac artery of the same side. It divides at one* 

 before it.has emerged from above the kidney into an internal iliac and an externa 

 iliac artery. The external iliac forks after a short distance. The medial and largei 

 branch supplies the muscles of the pelvis and as the femoral artery enters tht 

 thigh. The smaller and lateral branch passes deep dorsally to the point when 

 the ilium is articulated to the sacral ribs; here it passes dorsal to a nerve anc 

 turns ventrally as the sciatic artery into the hind leg, running along the media 

 surface of the ilium. The internal iliac is best followed by replacing the kidnej 

 against the dorsal wall, pulling the large intestine backward and locating the 

 point of origin of the internal iliacs from the common iliac. The chief brand: 

 of the internal iliac is the hemorrhoidal artery which passes forward along the 

 side of the large intestine; in addition there are branches to the bladder, the 

 reproductive organs, and the pelvic region in general. 



Draw the dorsal aorta and its. branches. 



8. The structure of the heart. — Separate the heart of the turtle by cutting 

 across the great vessels and remove it from the body. The posterior chambei 

 of the heart is the sinus venosus which receives the four great systemic veins 

 Clean out the blood from the sinus. It is a thin-walled chamber attached to the 

 right auricle, into which it opens by the sin-auricular opening guarded by a pail 

 of thin valves. Open each auricle by making a slit in the margin and washing 

 out the blood clots. The walls of the auricles are somewhat spongy. Look intc 

 the left auricle and note the thin inter auricular septum which completely separates 

 the cavity of the left auricle from that of the right one. Find the opening of the 

 pulmonary veins into the dorsal wall of the left auricle near the septum. Fine 

 on each side the large auricula-ventricular opening between each auricle and the 

 ventricle. Make a cut all of the way around the margin of the ventricle so as 

 to make dorsal and ventral flaps of the ventricle. Spread apart the two flaps 

 cautiously extending your cut inward until the two flaps are attached only along 

 the base of the ventricle. Note the exceedingly thick walls of the ventricle anc 

 the muscular columns projecting into the interior. The cavity of the ventricle 

 is a broad but flattened cavity usually containing a spongy network which ma} 

 be cleaned out. Spreading the two flaps widely, note in the base of the ventricl< 

 a band passing across from one side to the other. On each side of this band ii 

 an auricula-ventricular opening. The band is a continuation of the interauricula 



