Penis - the penis of the horse is of the musclocavernous type. The internal portion is erectile tissue that becomes engorged with blood when the stallion is aroused. It consists of 3 regions:
1. Root – attached to the skeletal system 2. Shaft – main part 3. Glans – enlarged free end
The root of the penis is attached to 2 lateral ligamentous crura which arises from the ischiatic arch, bends forward between the thighs and soon unites in a single corpus cavernosum . The corpus cavernosum makes up the dorsal aspect of the interior of the penis of the shaft. The corpus spongiosum surrounds the penile urethra and expands over the apex of the penis to form the distinctive glans penis. The tip of the penis is indented by the urethral sinus, through which the urethral process passes.
Vascular spaces enclosed by connective tissue and smooth muscle within the cavernosum & spongiosum fill with blood during erection.
The flaccid penis is about 50 cm long and 3-5 cm in diameter. During an erection the penis increases in size by about 50%.
Prepuce – The prepuce of the horse is formed by 2 folds of preputial skin, one inside the other and houses the penis. The folds are lubricated by natural, greasy smegma.
Accessory Sex Glands – There are 4 sets of accessory glands which all empty their secretions into the urethra. Recall that the urethra is the transport tube for urine from the bladder to the penis. It is also the transport tube for semen . These glands produce seminal fluid for transport of sperm.
1. Seminal vesicles 2. Prostate gland 3. Bulbourethral glands 4. Ampulla glands
Accessory sex glands are present in geldings although they are much reduced in size.
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