The action of extrinsic penile muscles during copulation in the male dog.

Abstract

AbstractElectromyographic activity of the bulbocavernosus (BC), ischiocavernosus (IC), and ischiourethral (IU) muscles was recorded during copulation in male dogs to examine the role of these muscles in the vascular engorgement process as related to the mechanisms responsible for initiating and maintaining the genital lock. In other dogs the IU muscle was severed to ascertain the influence this would have on the genital lock. No particular function in the engorgement process could be assigned to the IC muscle. Recordings from the BC muscle are consistent with the suggestion that rhythmic contraction of this muscle plays a role in pumping blood from the proximal parts of the corpus spongiosum into more distal parts of this cavernous erectile body. This would facilitate rapid engorgement of the bulbus glandis which is the structure that locks the dogs together. Recordings from the IU muscle reveal that this muscle contracts tonically just after intromission apparently also facilitating erection of the bulb by occluding venous return. Section of this muscle prevented engorgement of the bulb and eliminated the genital lock.