Corpus cavernosum penis pressure and external penile muscle activity during erection in the goat.

Abstract

The corpus cavernosus penis (CCP) and electromyographic (EMG) activity of the external penile muscles were recorded during erection and ejaculation of the goat. The mean peak CCP pressures were 18, 83, and 7003 mm Hg for the quiescence, mild erection, and maximum erection stage of the penis. The contractions of the ischiocavernosus muscles (1CM) were in phase with the peak pressures of the CCP. Anesthesia of the 1CM prevented the high peak CCP pressures, indicating that these muscles are the source of energy for the high pressure recorded. The mechanism of erection in man and animals has been under investigation for many years. Explanations for the mechanism of penile erection have been primarily theories deduced from anatomical studies and limited physiological experimentation (Deysack, 1939; Denamur and Simonnet, 1950; Conti, 1952). It is generally considered that erection of the penis is produced by a combination of elevated arterial pressure, dilation of the arteries to the penis, restricted venous return, relaxation of the walls of the cavernous spaces, and contraction of the external penile muscles. The importance of each factor has not been delineated. The role of the ischiocavernosus muscles (1CM) and bulbocavernosus muscles (BCM) is an example for consideration. Henderson and Roepke (1933) noted the pumping action of these muscles, but attached little significance to it. Sisson and Grossman (1953) stated that the contraction of the 1CM pulls the