The Male Reproductive Tract

This is the caudal end of the dog, and dorsal is to the right of the image.

 In this image, the muscles of the penis (A) are clearly dissected out. The specimen is on its right side with the head facing up and to the left.  The ischiocavernosus muscle (B) arises from the ischium and surrounds the crus and corpus cavernosum; As the urethra exits the pelvis, it becomes surrounded by bodies of cavernous tissue (bulbs of the penis), which are initially surrounded by muscle. The urethralis muscle becomes the bulbospongiosus muscle (C) as it surrounds the bulbs of the penis and corpus spongiosum; Finally, there is a pair of thin strap muscles which course along the caudoventral surface of the penis, the retractor penis muscles (D).