Page:Laboratory Manual of the Anatomy of the Rat (Hunt 1924).djvu/115

Rh parallel to the horn of the uterus in the broad ligament. Trace the uterine artery caudally to its origin.

The two iliolumbar arteries pass laterally in the lumbar region from the dorsal aorta, along the dorsal surface of the abdominal cavity, giving off branches to the muscles of the back. Trace the terminal branches.

The inferior mesenteric artery branches from near the posterior end of the dorsal aorta, sends branches to the rectum and descending colon, passes anteriorly along the latter, and anastomoses with the superior mesenteric artery. Is this anastomosis always present?

The aorta bifurcates at its posterior extremity, forming the right and left common iliac arteries. These give off dorsal branches to the muscles of the back, then divide into the external and internal iliac (hypogastric) arteries. The latter, which runs dorsally, divides into two main branches, one which passes laterally to the proximal region of the thigh, while the other passes caudally through the pelvic region. Dissect out these branches. The external iliac artery passes to the median surface of the thigh, there becoming the femoral artery. This gives off the saphenous artery, then penetrating the thigh it courses distally to the foot, supplying branches to the muscles of the thigh and shank. Trace the saphenous along the median surface of the shank, and note that its terminal branches enter the foot.

The middle sacral artery arises from the dorsal aorta near its posterior end and proceeds caudally through the pelvic region into the tail. Trace it and observe its branches.

The unpaired lumbar arteries pass dorsally from the abdominal section of the dorsal aorta. They correspond to the intercostal arteries of the thoracic region. The lumbar arteries bifurcate ventral to the vertebral column,