Penis and Prepuce Flashcards
Cavernous/erectile tissue of the penis
-Corpus cavernosum penis: located in the root and most of the body of the penis
-Corpus spongiosum penis: located throughout the penis; more delicate that CCP; has larger blood spaces separated by thinner septae
-Corpus spongiosum glandis of the bulbus glandis: located in the bulbus glandis of the glans penis
-Corpus spongiosum glandis of the pars longa glandis: located in the pars longa glandis of the glans penis
Ischiocavernosus m.
Paired skeletal muscle; arises from ischiatic tuberosity, covers the crus of the penis and inserts distally on the crus
Contraction of mm. causes blood to flow through corpus cavernosum and corpus spongiosum during erection; also aids in propelling sperm through urethra
Bulbospongiosus m.
Skeletal muscle; covers bulb of penis and inserts on the body of the penis; located between ischiocavernosus muscles; palpable
Contraction of mm. causes blood to flow through corpus cavernosum and corpus spongiosum during erection; also aids in propelling sperm through urethra
Retractor penis m.
Paired smooth muscle; retracts the penis
Ischiourethralis m.
Paired; contracts during erection resulting in fibrous ring clamping down on dorsal vv. of the penis
Regions of the penis
Root, body, glans
Root of penis in dogs
-Crura (left and right) - composed of corpus cavernosum penis; covered by ischiocavernosus m.
-Bulb of penis - expansion of corpus spongiosum penis; covered caudally by bulbospongiosus m.
-Urethra surrounded by corpus spongiosum penis
-Retractor penis m. - courses along caudal aspect of penis
Body of penis in dogs
-Corpus cavernosum penis surrounded by tunica albuginea
-Urethra surrounded by corpus spongiosum penis
-Proximal part of os penis - corpus cavernosum ends and os penis begins
-Retractor penis m.
Os penis - dogs
Adds rigidity for intromission
Fibrocartilage tip deforms the apex of the penis in the vagina
Urethra passes through urethral groove on ventral surface
Located in distal part of body of the penis and in entire glans of penis
Glans of penis in dogs
-Composed of bulbus glandis and pars longa glandis
-Os penis
-Urethra surrounded by corpus spongiosum penis
Canine prepuce
-Fold of skin covering glans of penis
-Preputial orifice
-Pars longa glandis and half of bulbus glandis project into preputial cavity
-Preputial fornix
-Lymphoid nodules are present near fornix on the internal and penile laminae
Components of feline penis
-Apex (directed caudoventrally)
-Small os penis
-Root
-Body
-Small glans
-Keratinized spines on free end of penis (testosterone dependent, regress completely after castration)
Feline prepuce
-Preputial orifice
-Preputial fornix
-Preputial mm. pull the prepuce cranially during copulation
Blood supply to the penis
-Internal pudendal artery which continues into artery of the penis - main source of blood supply
-External pudendal artery
Artery of the penis
-Artery of the bulb - supplies bulb of penis, corpus spongiosum penis, penile urethra
-Deep artery of the penis - supplies the tunica albuginea, corpus cavernosum penis, and os penis
-Dorsal artery of penis - supplies the prepuce, superficial surface of penis, and pars longa glandis (preputial, deep, and superficial brs.); blood from pars longa glandis supplies bulbus glandis (no direct blood supply to bulbus glandis)
Venous return from penis
Veins drain into internal and external pudendal veins
-Right and left dorsal veins of the penis join at ischial arch before diverging and draining into right and left internal pudendal veins
Venous return flow from penis
Internal pudendal v. -> internal iliac v.
External pudendal v. -> external iliac v.
Right and left internal and external iliac vv. join to form common iliac vv. -> join to form caudal vena cava
Lymphatics of the penis
Lymphatic vessels from penis course to superficial inguinal lymph nodes -> course through inguinal canal to medial iliac lnn.
Innervation to the penis
Deep perineal brs. - innervate ischiocavernosus, bulbospongiosus, and ischiourethralis mm.
Dorsal nerve of penis - courses with dorsal arteries and veins; chief sensory nerve of glans penis
Erection of penis
During non-erection, blood bypasses vascular spaces of erectile tissue
During erection:
-Pelvic n. (parasympathetic fibers) relaxes smooth muscle (retractor m.), allowing inc. in blood flow to cavernous spaces in erectile tissue; peripheral veins are compressed, occluding venous return
-Somatic sensory stimulation of glands leads to stimulation of mm.
-Somatic sensory innervation of vaginal and vestibular mucosa leads to stimulation of constrictor vestibuli and constrictor vulvae mm.
-Bulbus glandis is last structure to enlarge - no direct arterial supply
Phimosis
Congenital or acquired narrowing of preputial orifice; penis is unable to protrude from prepuce
Paraphimosis
Extended penis is unable to be withdrawn back into prepuce
