Branching mode of the middle rectal artery from the prostatic artery in the dog.

The branching mode of the middle rectal artery from the prostatic artery was studied by gross dissection in 50 male dogs. The prostatic artery arose at the level of the 1st-3rd sacral vertebra from the internal pudendal artery, and gave off the ductus deferential and the middle rectal arteries, and supplied the prostate. The middle rectal artery ran caudally along the pelvic peritoneum, and supplied the rectum ampulla. The branching mode of the middle rectal artery could be classified into four types. Nineteen cases on the right side and 22 cases on the left side showed that the middle rectal artery was a first visceral branch of the prostatic artery. Fifteen cases on the right side and 11 cases on the left side showed that it was a second visceral branch of the prostatic artery which gave off the ductus deferential artery as its first visceral branch. Nine cases on the right side and 7 cases on the left side showed that it arose at the prostatic artery ramifying at the surface of the prostate. Seven cases on the right side and 10 cases on the left side showed that it arose at the urethral branch of the prostatic artery.