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Review Of Literature Chapter 1 Anatomy And Emberyology of the Penis And Male Urethra Fig (1): Ventral aspect of the constituent erectile masses of the penis in erect position. (Healy j et al, 2008). The penis, the male copulatory organ, comprises an attached radix or root in the perineum and a free, normally pendulous corpus or body completely enveloped in skin. Root of the Penis As shown in figure before the root of the penis comprises the three masses of erectile tissue in the urogenital triangle: the two crura 4 Review Of Literature and the bulb of the penis, firmly attached to the pubic arch and perineal membrane respectively. The crura are the posterior regions of the corpora cavernosa and the bulb, the posterior end of the corpus spongiosum (Healy j et al, 2008). Each crus penis commences behind as a blunt, elongated but rounded process, attached firmly to the everted edge of the ischiopubic ramus and covered by the ischiocavernosus. Anteriorly it converges towards its fellow and is slightly enlarged posterior to this. Near the inferior symphyseal border the two crura bend sharply down and forwards to become the corpora cavernosa (Healy j et al, 2008). The bulb of the penis lies between the crura and is firmly connected to the inferior aspect of the perineal membrane, from which it receives a fibrous covering. Oval in section, the bulb narrows anteriorly into the corpus spongiosum, bending sharply down and forwards at this point. Its convex superficial surface is covered by bulbospongiosus; its flattened deep surface is pierced above its centre by the urethra, which traverses it to reach the corpus spongiosum. This part of the urethra has an intrabulbar fossa (Healy j et al, 2008). Corpus of the Penis The corpus of the penis contains three elongated erectile masses, capable of much enlargement when engorged with blood during erection. When flaccid it is cylindrical, but when erect it is triangular with rounded angles, The surface which is poster superior during erection is termed the dorsum of the penis and the opposite aspect the urethral surface. The erectile masses are termed the right and left 5 Review Of Literature corpora cavernosa, and the median corpus spongiosum penis, continuations of the crura and bulbous penis (Healy j et al, 2008). The corpora cavernosa form most of the corpus, (fig 2) In close apposition throughout, they have a common fibrous envelope and are separated only by a median fibrous septum. On the urethral surface their combined mass has a wide median groove, adjoining the corpus spongiosum, dorsally a similar but narrower groove contains the deep dorsal vein (Healy j et al, 2008). Fig (2 ): Cross section of the penis at the junction of its middle and distal thirds. The corpora end distally in the hollow, proximal aspect of the glans penis in a rounded cone, on which each has a small terminal projection. They are enclosed in a strong fibrous tunica albuginea, consisting of superficial and deep straia. The superficial fibers are longitudinal, forming a single tube round both corpora; the deep fibers are circularly orientated and surround each corpus separately, joining together as a median septum of the penis, which is thick and complete 6 Review Of Literature proximally but imperfect distally where it consists of a pectiniform (comb-like) series of bands; hence the term pectiniform septum (Healy j et al, 2008). The corpus spongiosum penis, traversed by the urethra, adjoins the median groove on the urethral surface of the conjoined corpora cavernosa. It is cylindrical, tapering slightly distally, and surrounded by a tunica albuginea. Near the end of the penis it expands into a somewhat conical enlargement like an acorn, whence its name, glans penis (Healy j et al, 2008). The glans penis projects dorsally over the end of the corpora cavernosa, with a shallow concave surface to which they are attached. Its base has a projecting corona glandis, overhanging an obliquely grooved neck of the penis. The navicular fossa of the urethra is in the glans and opens by a sagittal slit on or near its apex. Fig (3 ): Arrangement of the Buck's and dartos fasciae ( Gregory et al ; 2012) 7 Review Of Literature The superficial penile fascia, (fig 3) which is devoid of fat, consists of loose connective tissue, invaded by a few fibers of dartos muscle from the scrotum, and hence called the Dartos fascia. As in the suprapubic abdominal wall, the deepest layer is condensed here as the fascia penis or Buck's fascia surrounding both the corpora cavernosa and corpus spongiosum and separating the superficial and deep dorsal veins. At the penile neck it blends with the fibrous covering of all three corpora. Proximally, it is continuous with the dartos muscle and with the fascia covering the urogenital region of the perineum (Healy j et al, 2008), as shown in figure 3 showing arrangement of the Buck's and dartos fasciae ( Gregory et al ; 2012) The corpus penis is supported by two ligaments continuous with its fascia and consisting largely of elastin fibers. The fundiform ligament, stemming from the lowest part of the linea alba, splits into two lamellae which skirt the penis and unite below with the scrotal septum. The triangular suspensory ligament, deep to the fundiform ligament, is attached above to the front of the pubic symphysis, blending below, on each side, with the fascia penis (Gregory et al, 2012) The male urethra is divided into six parts: bladder neck, prostatic urethra, membranous urethra, bulbous urethra, penile (pendulous urethra), and the fossa navicularis within the distal glans. The corpus spongiosum is the erectile tissue inferior to the corpora cavernosa, the penile and bulbar urethra lie within the spongiosum, the penile urethra lies in a central location within the spongiosum, whereas the bulbar urethra lies eccentrically closer to the dorsal spongiosum prior to 8 Review Of Literature exiting dorsally to become the membranous urethra to join the prostate (Brooks ; 2007). This is described in the following (fig 4&5) showing post wall of urethra and parts of urethra. Fig (4): Posterior wall of the male urethra. (Gregory et al; 2012) Fig (5): Parts of the urethra (Gregory et al; 2012) 9 Review Of Literature The superficial fascia of the penis, or dartos fascia, is a part of the membranous layer of the superficial fascia of the groin and perineum or Colles’ fascia. (Fig6) Imbedded in it are the superficial penile arteries and the superficial dorsal vein, vessels that supply the skin. This layer is only loosely applied to the one beneath it and, hence, is mobile. It separates the superficial veins from the deep dorsal veins. Buck’s fascia has a dense structure, in contrast to the loose superficial fascia of the penis. It is composed of longitudinally running fibers and is firmly attached to the underlying tunica albuginea. (Gregory et al; 2012) Fig (6): Arrangement of the tunica albuginea (Gregory et al; 2012) The deepest layer is the tunica albuginea, forming a thick white coat set in a fibroareolar matrix (fig 6). This layer encloses the corpora 10 Review Of Literature cavernosa and the corpus spongiosum. It is covered closely by Buck’s fascia. Two layers may be identified: (1) an outer longitudinal coat and (2) an inner circular coat. The tunica albuginea becomes thicker ventrally as it forms a groove for the corpus spongiosum. Ventromedially, it is thinned as the outer coat becomes attenuated, leaving only the inner coat. This difference in the thickness of the tunic explains the greater susceptibility of the urethra to inadvertent entry during insertion of a penile prosthesis. Similarly, at the crura, it is only the inner coat that provides the cover. The two corpora cavernosa are separated in the sagittal plane by a dense tunica albugineal layer that passes between them as the intercavernous septum. The septum is incomplete distally, being perforated on its dorsal margin by vertically oriented openings in the pectiniform septum that provide free vascular communication between the corpora. Continuous with the inner surface of the tunica albuginea within the corporal bodies are numerous flattened columns or sinusoidal. (Gregory et al; 2012) Most cases of hypospadias, regardless of severity, are associated with a prepuce that could be sufficient to create a neourethra to bridge the existing gap and cover the repair with skin. Success is in a major part dependent on three preconditions: The inner layer of the prepuce has to be long enough. The epithelial surface of the prepuce has to be adequate. The subcutaneous tissue between the outer and inner layer of the prepuce has to be sufficient and carry enough blood vessels for vascularisation of the two layers. 11 Review Of Literature However, any technique using the prepuce for the repair affect the blood supply and the result. Knowledge of the blood supply of the prepuce is essential so that preservation of the preputial vascularisation is not ignored (Zachariou, 2004). Mucous Membrane of the Male Urethra The penile urethra is lined with pseudostratified columnar epithelium. However, islands of stratified squamous epithelium are found near the meatus, reflecting the ectodermal source of this portion of the urethra. The urethra in the distal portion of the glans is lined with more differentiated squamous cells lying over connective tissue papillae. These cells even become keratinized at the meatus, which is further evidence of their separate origin. (Gregory et al ; 2012) The surface epithelium has no muscularis mucosae because it is separated from the smooth muscle of the spongy tissue by loose connective tissue. The lateral and especially the dorsal surfaces of the fossa navicularis contain numerous pockets. (Gregory et al ; 2012) One large pocket, the lacuna magna (Morgagni), opens on the roof of the fossa navicularis. On the anterior wall of the distal urethral segment are small recesses, the urethral lacunae. In addition, on the posterior wall of the penile and bulbar urethra are orifices of the ducts draining minute clusters of mucus-secreting cells, the glands of Littré, that lubricate the urethra prior to ejaculation. (Gregory et al ; 2012) These ducts run obliquely beneath the submucosal connective tissue to open toward the meatus and so may be entered inadvertently during urethral instrumentation. These glands, rich in goblet cells, penetrate the spongy tissue among the trabeculae and vascular spaces. 12 Review Of Literature This tissue reacts by dense fibrous proliferation to infection arising in these glands or from urinary extravasation. Subsequent contraction of the inflamed spongy tissue creates the spongiofibrosis of urethral strictures. (Gregory et al ; 2012) The preputial skin with its accompanying superficial fascia and vessels is ideal for the constructions of flaps for hypospadias repair. It is relatively thin and pliable, and especially the thin epithelialised layer on the inside of the prepuce tolerates prolonged contact with urine better than any other tissue except the bladder urothelium (Zachariou, 2004). Urethral Sphincters Of the two urethral sphincters, the internal sphincter vesical controls the vesical neck and the prostatic urethra above the ejaculatory ducts. It is composed of no striated muscle and supplied by sympathetic fibers from the vesical plexus. The external sphincter urethrae surrounds the membranous urethra; it consists of striated muscle and is supplied by the perineal branches of the pudendal nerve (S2, 3 and 4); it is voluntary after early infancy. (Gregory et al ; 2012) 13 Review Of Literature Blood Supply of the Urethra and penis Fig (7): normal position of the neuro-vascular bundle (Gregory et al; 2012) Regarding the arterial supply of the urethra, (fig7&8&9) there are anastomotic communications between the dorsal arteries and the bulbourethral arteries, the urethra receives arterial supply from both distal and proximal directions, this enables complete transaction of the urethra without necrosis of the distal segment (Yiee et al,2010). Fig (8): arterial supply of the urethra (Kavoussi et al, 2012) 14 Review Of Literature (1) Superficial Arterial System The superficial arterial supply to the penile skin and prepuce lies in the superficial layer of the superficial fascia of the penis overlying Buck’s fascia. The penile skin is well-vascularized with a very flexible cutaneous blood supply of coiled vessels running along the shaft. Two more or less symmetrically arranged, longitudinally oriented vessels, the superficial penile arteries, arise from each inferior external pudendal artery, a branch of the femoral artery. (Gregory et al; 2012) Regarding the prepuce, its arterial supply is via four branches from the inferior external pudendal arteries (2 dorso-laterally and 2 ventro-laterally). (fig9) These arteries divide into anterolateral and posterolateral branches, so in hypospadias repair it is necessary to keep intact at least one and preferably two of the four branches of these arteries supplying the penile skin . (Uskiewenski et al;1982) The superficial penile arteries divide on each side, usually into a dorsolateral and a ventrolateral branch. However, there are equally common arrangements that make the skin partially dependent on one or the other principal superficial artery. When the blood supply is symmetric, each artery enters the lateral aspect of the penis near the base, then branches as it runs out the shaft to form a dorsolateral and a ventrolateral vessel. When the total supply comes from one artery, that vessel divides soon after entering the penis, so that one branch crosses over the dorsum to the opposite side. In either case, subsequent branches course dorsolaterally and ventrolaterally on each side. At intervals, these vessels give off fine branches to the skin. The only point of connection between the deep and superficial systems is an 15 Review Of Literature anastomosis at the coronal sulcus, where the superficial vessels circle back dorsally to join the dorsal artery of the penis(. (Gregory et al ; 2012) Also there is a fact that a flap from the shaft will have a better blood supply than one from the prepuce, which in turn, will be more vascular than one taken from the inner preputial surface, because the vessels are arranged axially, only longitudinal pedicles can be raised, because the prepuce is not supplied by vessels distally from the corona, all flaps must be based on the superficial fascial system of blood vessels that enter the prepuce proximally (Hinman et al; 1991) Fig (9):the prepuce and its blood supply the prepuce and its blood supply (Gregory et al ; 2012 ) The blood supply of the penile skin (fig10) is symmetrical (Juskiewenski et al. 1982). The superior and inferior external pudendal arteries arise from the femoral artery. They are attached to the Scarpa fascia, which extends to the base of the penis. At this point they divide into four branches as superficial penile arteries. Two enter the 16 Review Of Literature superficial penile fascia dorsolaterally and two enter it ventrolaterally. Numerous collaterals between these four arteries create a fine subcutaneous arterial plexus up to the preputial ring (Quartey 1997). Behind the sulcus in the distal part of the penile shaft, small vessels penetrate the Buck's fascia, making an anastomosis with the dorsal penile artery. Beyond the preputial ring on the inner surface the terminal branches become minute. Variations of the superficial penile arteries are possible with dominance of one side pair. (Zachariou, 2004). Fig (10): Peripheral arterial blood supply of the penis The blood supply to the frenulum (fig11) is also symmetrical and arises from the dorsal penile artery, which branches at the level of the sulcus with small arteries that curve around each side of the distal shaft to enter the glans and the frenulum ventrally. (Zachariou, 2004). 17 Review Of Literature Fig (11): Arterial blood supply of the frenulum (2) Deep Arterial Supply to the Penis The anterior branch of the internal iliac artery divides to form the inferior gluteal artery and the internal pudendal artery. Viewed from within the pelvis, the internal pudendal artery passes beneath the sacrospinous ligament and over the sacrotuberous ligament and bifurcates into the perineal artery and continues as the penile artery, which runs under the superficial transverse perineal muscle and the symphysis. (Gregory et al; 2012) The penile artery pierces the urogenital diaphragm along the medial margin of the inferior ramus of the ischium behind the superficial transverse perineal muscle near the bulb of the urethra, and divides into three branches: (1) the bulbourethral artery (artery to the bulb of the penis), (2) the urethral artery, and (3) the cavernous artery or the deep artery of the penis. It then terminates as the dorsal artery of the penis. Considerable variation can be found: an accessory internal pudendal artery is common, arising from the obturator artery, the 18 Review Of Literature inferior vesical artery, or the contralateral superior vesical artery. It is this alternate but essential blood supply to the corpora that may be inadvertently divided in total prostatectomy and cystectomy, resulting in vasculogenic impotency. (Gregory et al; 2012) The bulb urethral artery (subject to several variations in origin, occasionally arising from the cavernous, dorsal, or accessory pudendal arteries) supplies the bulb of the urethra, the corpus spongiosum, and the glans. These structures are anatomically independent from the body of the penis. This, the first branch of the penile artery, is a short, relatively large-caliber artery that passes medially to traverse the inferior layer of the urogenital diaphragm before entering the bulb. It supplies the bulb through a posterior group of branches and also supplies the proximal quarter of the cavernous tissue of the corpus spongiosum through an anterior group. The urethral artery, the second branch, is not always present. It may arise from the artery to the bulb, but if present, it more commonly takes origin directly from the penile artery or from the cavernous artery or dorsal artery. It runs on the ventral surface of the corpus spongiosum beneath the tunica albuginea. (Gregory et al; 2012) 19 Review Of Literature Fig (12): arterial supply of the urethra (Gregory et al; 2012) (3) Venous drainage of the penis and urethra is through: The venous drainage of the penile skin and prepuce is less well organized. Multiple minute veins in the prepuce form a plexus without particular orientation joining the superficial dorsal penile vein, which drains into the external pudendal vein, which in turn empties into the saphenous or femoral vein (Zachariou, 2004). Fig (13): Peripheral venous drainage of the penis 20 Review Of Literature (1) the deep dorsal vein lying in the dorsal groove between the corporal bodies beneath Buck's fascia. There is free anastomosis with veins from the corpus spongiosum (Fig 10) At the base of the penis this large vein passes between the two divisions of the suspensory ligament and enters the plexus of veins around the prostate. (2) superficial veins from the penile skin drain through a superficial dorsal vein, which empties into the saphenous system. (3) The crural vessels, departing the corpora cavernosa at the crus of the corpora and draining into the periprostatic plexus. (4) the cavernosal venous system departing the corpora proximal to the crus in part to join the dorsal vein of the penis and the periprostatic plexus. (Gregory et al; 2012) Fig (14): Deep venous drainage of the urethra and penis. From (Horton et al, 1990) 21 Review Of Literature The multiple small veins in the prepuce are distributed without particular orientation. In the skin of the shaft, they join one or two superficial penile veins that drain through the inferior external pudendal vein into the saphenous vein.(Gregory et al; 2012) (4) Lymphatic Drainage of the Penis and Urethra The lymphatic drainage from the glans penis passes to the deep inguinal and external iliac lymph nodes, while lymphatics from the deep urethra drain into the hypogastric and common iliac lymph nodes (Tanagho, 1992). The surface of the glans penis has three superposed networks, one in the papillae, another in the superficial mucosal layer, and a third beneath the other two. The collecting trunks converge on the frenulum, where they pick up collectors from the urethral mucosa. One to three trunks then pass around to the dorsum in the coronal sulcus to join those from the opposite side. One or more major collecting trunks running with the deep dorsal vein carry the lymph to the region of the suspensory ligament where they join the presymphyseal plexus. Two or three trunks run from this plexus to the superficial inguinal nodes along either a femoral or an inguinal path. Delicate preputial lymphatics arise both from the inner and, more abundantly, from the outer surfaces of the prepuce. As they run proximally, they anastomose and curve to become confluent on the dorsum .(Gregory et al 2012) From 5 to 10 channels course to the base of the penis, uniting as they go. The penile skin proper is drained by lymphatics that run from the median raphe obliquely around the penis to join the dorsal lymphatic channels already draining the prepuce. At the base of the 22 Review Of Literature penis, branches from the skin and prepuce connect with a presymphyseal plexus before passing right and left to join trunks draining the perineal and scrotal skin. The joint trunks run with the superficial external pudendal vessels to drain into the superficial inguinal lymph nodes, especially the super medial ones. Anastomoses loosely connect the right and left sides (Gregory et al; 2012) Some drainage occurs through the femoral route, passing into the femoral canal to enter a deep node there, to enter the node of Cloquet, and also to enter a medial retro femoral node. For the inguinal route, a single trunk approaches the inguinal canal below the spermatic cord to reach the lateral retro femoral node. Thus, the lymphatics of the penile skin empty through the superficial lymphatic drainage system into the superficial inguinal nodes, particularly the super medial group, whereas the glans and penile urethra drain into the deep inguinal nodes and the presymphyseal nodes and, occasionally, into the external iliac nodes.(Gregory et al 2012) Regarding the nerve supply and the blood supply of the penis, it is important to note that the dorsal nerves do not lie directly in the dorsal midline, but rather extend from the 11 and 1 O’clock positions, the structure of hypospadiac penis has showed that the nerves and the corporal bodies have the same anatomical relationship as the normal penis, the most important difference between the normal and hypospadiac penis was in the vascularity and the deficient corpus spogiosum surrounding the abnormal part of the urethra (Baskin et al;2000) 23