7877402 male reproductive system

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PENIS Urethra Prostatic Membranous penile TESTIS Scrotum Epididymis Vas deferens Glands Cowpers Prostate Seminal vesicle Bulbourethral gland

PENIS Organ for copulation in males pendulous organ suspended from the front and sides of the pubic arch and containing the greater part of the urethra. In the flaccid condition it is cylindrical in shape, but when erect assumes the form of a triangular prism with rounded angles, one side of the prism forming the dorsum.

3 layers It is composed of three cylindrical masses of cavernous tissue bound together by fibrous tissue and covered with skin. Two of the masses are lateral, and are known as the corpora cavernosa penis the third is median, and is termed the corpus spongiosum (cavernosum urethræ)

The Corpora Cavernosa Penis form the greater part of the substance of the penis. For their anterior three-fourths they lie in intimate apposition with one another, but behind they diverge in the form of two tapering processes, known as the crura, which are firmly connected to the rami of the pubic arch.

Traced from behind forward, each crus begins by a blunt-pointed process in front of the tuberosity of the ischium. Just before it meets its fellow it presents a slight enlargement, named by Kobelt the bulb of the corpus cavernosum penis. Beyond this point the crus undergoes a constriction and merges into the corpus cavernosum proper, which retains a uniform diameter to its anterior end. Each corpus cavernosum penis ends abruptly in a rounded end

The Corpus Cavernosum Urethræ ( corpus spongiosum ) contains the urethra. Behind, it is expanded to form the urethral bulb, and lies in apposition with the inferior fascia of the urogenital diaphragm, from which it receives a fibrous investment.

The urethra enters the bulb nearer to the upper than to the lower surface. On the latter there is a median sulcus, from which a thin fibrous septum projects into the substance of the bulb and divides it imperfectly into two lateral lobes or hemispheres.

The three layers are enclosed by Fascia : Superficial fascia – continuation of the abdomen fascia Buck’s fascia – deep fascia Skin PARTS: Root: bulb and crus Body Glans Support : Suspensory ligament of the penis. Arises from the linea alba and inserts into the deep (buck’s) fascia

External features Glans corona Urethral meatus Prepuce Frenulum

a tube which connects the urinary bladder to the outside of the body. The urethra has an excretory function in both sexes to pass urine to the outside a reproductive function in the male, as a passage for semen . The external urethral sphincter is a striated muscle that allows voluntary control over urination .

In the human male, the urethra is about 8 inches (15 cm) long and opens at the end of the penis . The inside of the urethra has a spiral groove (like rifling in a gun barrel), which makes the urine flow in a wide stream. The urethra is divided into four parts in men, named after the location:

pre-prostatic urethra This is the intramural part of the urethra and varies between 0.5 and 1.5 cm in length depending the fullness of the bladder

prostatic urethra Crosses through the prostate gland . There are several openings: (1) a small opening where sperm from the vas deferens and ejaculatory duct enters, (2) the prostatic ducts where fluid from the prostate enters, (3) an opening for the prostatic utricle , but nothing is added from it. These openings are collectively called the verumontanum

membranous urethra A small (1 or 2 cm) portion passing through the external urethral sphincter . This is the narrowest part of the urethra. It is located in the deep perineal pouch . The ducts from the bulbourethral glands enter here.

spongy urethra (or penile urethra ) Runs along the length of the penis on its ventral (underneath) surface. It is about 15-16 cm in length, and travels through the corpus spongiosum . The ducts from the urethral gland enter here.

Blood supply Artery: internal pudendal artery(femoral a.) Dorsal artery Deep artery – copora cavernosa Artery of the bulb – spongiosum Vein: Dorsal vein to the internal pudendal vein Nerve – terminal branches of the pudendal nerve and pelvic plexuses

Medical problems of the urethra Hypospadias and epispadias are forms of abnormal development of the urethra in the male, where the meatus is not located at the distal end of the penis (it occurs lower than normal with hypospadias, and higher with epispadias). In a severe chordee , the urethra can develop between the penis and the scrotum . Infection of the urethra is urethritis , said to be more common in females than males. Urethritis is a common cause of dysuria (pain when urinating). Related to urethritis is so called urethral syndrome Passage of kidney stones through the urethra can be painful and subsequently it can lead to urethral strictures .

Scrotum The scrotum is an outpouching of the lower part of the anterior abdominal wall and contains the testes, the epididymides, and the lower ends of the spermatic cords Develops from the labial – scrotal folds which fuses to form the scrotum and contains the testis Skin is thin. Minimal fat to keep the temperature low Dartos muscle or tunic: fused deep and superficial fascia Smooth muscles for temp regulation Nerves – ilioinguinal, genitofemoral, dorsal nerves

The wall of the scrotum has the following layers: Skin Superficial fascia; the dartos muscle, which is smooth muscle, replaces the fatty layer of the anterior abdominal wall, and Scarpa's fascia (membranous layer) is now called Colles' fascia. External spermatic fascia derived from the external oblique Cremasteric fascia derived from the internal oblique Internal spermatic fascia derived from the fascia transversalis Tunica vaginalis, which is a closed sac that covers the anterior, medial, and lateral surfaces of each testis from the peritoneum

Blood Supply Subcutaneous plexuses and arteriovenous anastomoses promote heat loss and thus assist in the environmental control of the temperature of the testes. Arteries The external pudendal branches of the femoral and scrotal branches of the internal pudendal arteries supply the scrotum. Veins The veins accompany the corresponding arteries

Contents of the Superficial Perineal Pouch in the Male structures forming the root of the penis muscles bulbospongiosus muscles - situated one on each side of the midline, cover the bulb of the penis and the posterior portion of the corpus spongiosum. Their function is to compress the penile part of the urethra and empty it of residual urine or semen. The anterior fibers also compress the deep dorsal vein of the penis, thus impeding the venous drainage of the erectile tissue and thereby assisting in the process of erection of the penis.

Ischiocavernosus Muscles The ischiocavernosus muscles cover the crus penis on each side The action of each muscle is to compress the crus penis and assist in the process of erection of the penis.

Superficial Transverse Perineal Muscles The superficial transverse perineal muscles lie in the posterior part of the superficial perineal pouch Each muscle arises from the ischial ramus and is inserted into the perineal body. The function of these muscles is to fix the perineal body in the center of the perineum.

Nerve Supply All the muscles of the superficial perineal pouch are supplied by the perineal branch of the pudendal nerve

Perineal Body This small mass of fibrous tissue is attached to the center of the posterior margin of the urogenital diaphragm.It serves as a point of attachment for the following muscles: external anal sphincter bulbospongiosus muscle superficial transverse perineal muscles. Perineal Branch of the Pudendal Nerve The perineal branch of the pudendal nerve on each side terminates in the superficial perineal pouch by supplying the muscles and skin

Contents of the Deep Perineal Pouch in the Male the membranous part of the urethra the sphincter urethrae the bulbourethral glands the deep transverse perineal muscles the internal pudendal vessels and their branches, the dorsal nerves of the penis.

Membranous Part of the Urethra The membranous part of the urethra is about 0.5 in. (1.3 cm) long and lies within the urogenital diaphragm, surrounded by the sphincter urethrae muscle; it is continuous above with the prostatic urethra and below with the penile urethra. It is the shortest and least dilatable part of the urethra). Sphincter Urethrae Muscle The sphincter urethrae muscle surrounds the urethra in the deep perineal pouch. It arises from the pubic arch on the two sides and passes medially to encircle the urethra portion of the urethra.

Nerve Supply The perineal branch of the pudendal nerve supplies the sphincter. Action The muscle compresses the membranous part of the urethra and relaxes during micturition. It is the means by which micturition can be voluntarily stopped.

Bulbourethral Glands The bulbourethral glands are two small glands that lie beneath the sphincter urethrae muscle. Their ducts pierce the perineal membrane (inferior fascial layer of the urogenital diaphragm) and enter the penile The secretion is poured into the urethra as a result of erotic stimulation

Testis Primary male reproductive organ Contained with in the scrotum Endocrine and exocrine gland

The two testicles are egg-shaped male reproductive glands. They are suspended in a pouch of loose skin called the scrotum below and behind the penis. In maturity, they are usually slightly smaller than a golf ball. It is normal for one testicle to be larger than the other The testicles produce the hormone testosterone as well as sperm, the male reproductive cells.

Covered by tunica albuginea 1 Epididymis 2 Head of epididymis 3 Lobules of epididymis 4 Body of epididymis 5 Tail of epididymis 6 Duct of epididymis 7 Deferent duct (ductus deferens or vas deferens)

The epididymis is a narrow, tightly-coiled tube connecting rear of the testicles to the deferent duct (ductus deferens or vas deferens). The epididymis consists of three part Head Body tail.

The head of the epididymis is located on superior pole of testis. It stores sperm for maturation. The body of the epididymis is a highly convoluted duct which connects the head to the tail of the epididymis. Sperm mature in this section of the epididymis. The tail of the epididymis is continuous with the deferent duct.

The deferent duct is the excretory duct of the testis which joins the excretory duct of the seminal vesicle to form the ejaculatory duct.

Blood supply and lymphatic drainage The paired testicular arteries arise directly from the abdominal aorta and descend through the inguinal canal , while the scrotum and the rest of the external genitalia is supplied by the internal pudendal artery (itself a branch of the internal iliac artery ).

The testis has collateral blood supply from 1. the cremasteric artery (a branch of the inferior epigastric artery , which is a branch of the external iliac artery ) 2. the vasal artery (a branch of the superior vesical artery , which is a branch of the internal iliac artery ). Therefore, if the testicular artery is ligated, e.g., during a Fowler-Stevens orchiopexy for a high undescended testis, the testis will usually survive on these other blood supplies. Lymphatic drainage of the testes follows the testicular arteries back to the paraaortic lymph nodes , while lymph from the scrotum drains to the inguinal lymph nodes .

Accessory glands and structures Vas deferens Prostate Seminal vesicle Cowper’s gland Bulbo urethral gland

Vas deferes The vas deferens is a thick-walled tube about 18 in. (45 cm) long that conveys mature sperm from the epididymis to the ejaculatory duct and the urethra. It arises from the lower end or tail of the epididymis and passes through the inguinal canal. It emerges from the deep inguinal ring and passes around the lateral margin of the inferior epigastric artery It then passes downward and backward on the lateral wall of the pelvis and crosses the ureter in the region of the ischial spine. The vas deferens then runs medially and downward on the posterior surface of the bladder. The terminal part of the vas deferens is dilated to form the ampulla of the vas deferens. The inferior end of the ampulla narrows down and joins the duct of the seminal vesicle to form the ejaculatory duct.

Seminal vesicle The seminal vesicles are two lobulated organs about 2 in. (5 cm) long lying on the posterior surface of the bladder On the medial side of each vesicle lies the terminal part of the vas deferens. Posteriorly, the seminal vesicles are related to the rectum Inferiorly, each seminal vesicle narrows and joins the vas deferens of the same side to form the ejaculatory duct. Each seminal vesicle consists of a much-coiled tube embedded in connective tissue.

Blood Supply Arteries The inferior vesicle and middle rectal arteries.

Veins The veins drain into the internal iliac veins. Lymph Drainage The internal iliac nodes. Function The function of the seminal vesicles is to produce a secretion that is added to the seminal fluid. The secretions nourish the spermatozoa. During ejaculation the seminal vesicles contract and expel their contents into the ejaculatory ducts, thus washing the spermatozoa out of the urethra.

Ejaculatory Ducts The two ejaculatory ducts are each less than 1 in. (2.5 cm) long and are formed by the union of the vas deferens and the duct of the seminal vesicle. The ejaculatory ducts pierce the posterior surface of the prostate and open into the prostatic part of the urethra, close to the margins of the prostatic utricle their function is to drain the seminal fluid into the prostatic urethra.

Prostate The prostate is a fibromuscular glandular organ that surrounds the prostatic urethra It is about 1.25 in. (3 cm) long and lies between the neck of the bladder above and the urogenital diaphragm below. The prostate is surrounded by a fibrous capsule The somewhat conical prostate has a base, which lies against the bladder neck above, and an apex, which lies against the urogenital diaphragm below.

Relations Superiorly: The base of the prostate is continuous with the neck of the bladder, the smooth muscle passing without interruption from one organ to the other. The urethra enters the center of the base of the prostate. Inferiorly: The apex of the prostate lies on the upper surface of the urogenital diaphragm. The urethra leaves the prostate just above the apex on the anterior surface (Fig. 7-16).

Anteriorly: The prostate is related to the symphysis pubis, separated from it by the extraperitoneal fat in the retropubic space (cave of Retzius). The prostate is connected to the posterior aspect of the pubic bones by the fascial puboprostatic ligaments

Posteriorly: The prostate is closely related to the anterior surface of the rectal ampulla and is separated from it by the rectovesical septum (fascia of Denonvilliers). This septum is formed in fetal life by the fusion of the walls of the lower end of the rectovesical pouch of peritoneum, which originally extended down to the perineal body.

Laterally: The prostate is embraced by the anterior fibers of the levator ani as they run posteriorly from the pubis

Structure of the Prostate The numerous glands of the prostate are embedded in a mixture of smooth muscle and connective tissue, and their ducts open into the prostatic urethra. The prostate is incompletely divided into five lobes The anterior lobe lies in front of the urethra and is devoid of glandular tissue. The median, or middle, lobe is the wedge of gland situated between the urethra and the ejaculatory ducts. Its upper surface is related to the trigone of the bladder; it is rich in glands. The posterior lobe is situated behind the urethra and below the ejaculatory ducts and also contains glandular tissue. The right and left lateral lobes lie on either side of the urethra and are separated from one another by a shallow vertical groove on the posterior surface of the prostate. The lateral lobes contain many glands.

Function of the Prostate The prostate produces a thin, milky fluid containing citric acid and acid phosphatase that is added to the seminal fluid at the time of ejaculation. The smooth muscle, which surrounds the glands, squeezes the secretion into the prostatic urethra. The prostatic secretion is alkaline and helps neutralize the acidity in the vagina.

Blood Supply Arteries Branches of the inferior vesical and middle rectal arteries. Veins The veins form the prostatic venous plexus, which lies outside the capsule of the prostate (Fig. 7-16). The prostatic plexus receives the deep dorsal vein of the penis and numerous vesical veins and drains into the internal iliac veins. Lymph Drainage Internal iliac nodes. Nerve Supply Inferior hypogastric plexuses. The sympathetic nerves stimulate the smooth muscle of the prostate during ejaculation

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7877402 male reproductive system

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7877402 male reproductive system