Anatomy of the Reproductive System PDF
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Universidad Autónoma de Guadalajara School of Medicine
Dr. Rocha
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This document provides an overview of the anatomy of the reproductive system, covering both male and female structures. Numerous diagrams illustrate the various organs, their components and relationships.
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Anatomy of the Reproductive System Block III Dr. Rocha Class objectives 1. Identify and describe the anatomical features of external genitalia in males and females. 2. Describe the structures in the female reproductive system. 3. Describe the structures in the male reproductive system. 4. Differenti...
Anatomy of the Reproductive System Block III Dr. Rocha Class objectives 1. Identify and describe the anatomical features of external genitalia in males and females. 2. Describe the structures in the female reproductive system. 3. Describe the structures in the male reproductive system. 4. Differentiate the roles and anatomical characteristics of the male and female urethra. 5. Examine the vascular and nervous supply to reproductive organs. 1. External genitals External genitals The structures that form the external genitals are located in the urogenital triangle, as structures in the superficial perineal pouch which contains: a) the erectile structures and b) the muscles of the superficial perineal pouch Erectile structures 1/2 Two sets of erectile structures join to form the penis and the clitoris. A pair of cylindrically shaped corpora cavernosa, one on each side of the urogenital triangle, are anchored by their proximal ends to the pubic arch. These attached parts are often termed the crura (from the Latin for “legs”) of the clitoris or the penis. The distal ends of the corpora, which are not attached to bone, form the body of the clitoris in women and the dorsal parts of the body of the penis in men. Erectile structures 2/2a The second set of erectile tissues surrounds the openings of the urogenital system. In women the bulbs of the vestibule, are situated, one on each side, at the vaginal opening and are firmly anchored to the perineal membrane. Small bands of erectile tissues connect the anterior ends of these bulbs to a single, small, pea-shaped erectile mass, the glans clitoris. Erectile structures 2/2b In men, a single large erectile mass, the corpus spongiosum is anchored at its base to the perineal membrane (bulb of penis). The part that is not attached, forms the ventral part of the body of the penis and expands over the end of the body of the penis to form the glans penis. The urethra is enclosed by the corpus spongiosum and opens at the end of the penis, the external urethral orifice. Superficial perineal pouch The superficial perineal pouch contains three pairs of muscles: Ischiocavernosus, Bulbospongiosus, and Superficial transverse perineal Two of these three pairs of muscles are associated with the roots of the penis and clitoris; the other pair is associated with the perineal body. Female superficial features The vulva is the external female genitalia. On either side of the midline are two thin folds of skin termed the labia minora. The region enclosed between them is the vestibule. Anteriorly, the labia minora unite to form the frenulum; below the clitoris and above the urethral opening. Posteriorly, they unite to form the Fourchette. Within the vestibule, the vaginal opening is surrounded by a membrane, the hymen. The ducts of the para-urethral glands (Skene’s glands) open on each side of the lateral margin of the urethra. The ducts of the greater vestibular glands (Bartholin’s glands) open adjacent to the posterolateral margin of the vaginal opening. Posterior commissure Anal aperture Male superficial features Superficial components of the genital organs in men consist of the scrotum and the penis. The scrotum is the male homologue of the labia majora in women fused in the raphe. The penis consists of a root and body. The root of the penis is palpable posterior to the scrotum. The body of the penis is the pendulous part. The glans penis, has the external urethral opening at its tip, and its base is expanded to form a raised circular margin, the corona of the glans. The prepuce is a fold of skin at the neck of the glans that is continuous anteriorly with thin skin that tightly adheres to the glans and posteriorly with thicker skin loosely attached to the body. Scrotum Raphe 2. Female organs of reproduction Reproductive tract in women Major components of the reproductive tract in women consist of: an ovary on each side, and a uterus, vagina, and clitoris in the midline. In addition, a pair of accessory glands; the greater vestibular glands are associated with the tract. Ovaries The ovaries lie adjacent to the lateral pelvic wall just inferior to the pelvic inlet. Each of the two almond-shaped ovaries is about 3 cm long and is suspended by a mesentery (the mesovarium). The ovaries are the sites of egg production (oogenesis). Mature eggs are ovulated into the peritoneal cavity and normally directed into the adjacent openings of the uterine tubes by cilia. Uterus It consists of a body and a cervix, and inferiorly it joins the vagina. Superiorly, the uterine tubes project laterally and open into the peritoneal cavity immediately adjacent to the ovaries. The body of the uterus has a rounded superior end (fundus of the uterus). Each of the superior corners of the cavity is continuous with the lumen of a uterine tube. Its cavity is a narrow slit shaped like an inverted triangle. The inferior corner is continuous with the central canal of the cervix. The body of the uterus normally arches forward (anteverted) over the superior surface of the emptied bladder. Infundibulum Uterine tubes The uterine tubes extend from each side of the superior end of the body of the uterus to the lateral pelvic wall and are surrounded and supported by the mesosalpinx (a peritoneal fold). Fimbriae Each uterine tube has an expanded trumpetshaped end (the infundibulum), which curves around the superolateral pole of the related ovary. Its margin is rimmed with small finger-like projections termed fimbriae. The tube expands to form the ampulla and then narrows to form the isthmus, before joining with the body of the uterus. Fundus of uterus Cervix The cervix forms the inferior part of the uterus and is shaped like a short cylinder with a narrow central channel. Because the end of the cervix is dome shaped, it bulges into the vagina forming the fornix around the margin of the cervix where it joins the vaginal wall The tubular central canal of the cervix opens, below, as the external os, into the vaginal cavity and, above, as the internal os, into the uterine cavity. Vagina It is a distensible fibromuscular tube that extends from the perineum through the pelvic floor and into the pelvic cavity. The internal end of the canal is enlarged to form a region called the vaginal vault. The vaginal fornix is the recess formed between the margin of the cervix and the vaginal wall. The anterior wall of the vagina is related to the base of the bladder and to the urethra. Posteriorly, the vagina is related to the rectum. The vaginal canal is normally collapsed so that the anterior wall is in contact with the posterior wall. Its external opening (the introitus) is posterior to the external opening of the urethra. Greater vestibular glands Named Bartholin’s glands, are small, pea-shaped mucous glands that lie posterior to the bulbs of the vestibule on each side of the vaginal opening and are the female homologues of the bulbourethral glands in men. The greater vestibular glands are in the superficial perineal pouch (Wheras the bulbo-urethral glands in males are located within the deep perineal pouch.) The greater vestibular glands produce secretion during sexual arousal for vaginal lubrication. 3. Male organs of reproduction Reproductive tract in men The major components of the reproductive system in men are: testis, epididymis, ductus deferens, and ejaculatory duct on each side, and the urethra and penis in the midline. In addition, three types of accessory glands are associated with the system: a single prostate, a pair of seminal vesicles, and a pair of bulbo-urethral glands. Testes Each testis is enclosed within the end of an elongated musculofascial pouch, which is continuous with the anterior abdominal wall and projects into the scrotum. The sides and anterior aspect of the testis are covered by a closed sac of peritoneum (the tunica vaginalis). Each testis is composed of seminiferous tubules and interstitial tissue surrounded by a thick connective tissue capsule (the tunica albuginea). The seminiferous tubules at each end become straight tubules, which connect to a collecting chamber (the rete testis). The efferent ductules originate from the upper end of the rete testis, penetrate the capsule, and connect with the epididymis. Epididymis The epididymis courses along the posterolateral side of the testis. It has two distinct components: the efferent ductules, which form an enlarged coiled mass that sits on the posterior superior pole of the testis and forms the head of the epididymis. the body of the epididymis which continues inferiorly along the posterolateral margin of the testis and enlarges to form the tail of the epididymis at the inferior pole of the testis. The end of the epididymis is continuous with the ductus deferens. Scrotum Spermatic cord The spermatic cord is the tubular extension of the layers of the abdominal wall into the scrotum that contains all structures passing between the testis and the abdomen. Ductus deferens The ductus deferens is a long muscular duct that transports spermatozoa from the tail of the epididymis to the ejaculatory duct. It ascends in the scrotum as a component of the spermatic cord and passes through the inguinal canal. It descends medially on the pelvic wall and crosses the ureter posterior to the bladder. At this point, it expands to form the ampulla of the ductus deferens. At the base of the bladder it is joined by the duct of the seminal vesicle to form the ejaculatory duct that penetrates through the prostate gland to connect with the prostatic urethra. Seminal vesicles Each seminal vesicle is an accessory gland of the male reproductive system that contribute significantly to the volume semen. Each seminal vesicle is immediately lateral to and follows the course of the ductus deferens at the base of the bladder. The duct of the seminal vesicle joins the ductus deferens to form the ejaculatory duct. Prostate The prostate is shaped like an inverted rounded cone with a larger base, which is continuous above with the neck of the bladder and the internal urethral sphincter, and a narrower apex, which rests below on the pelvic floor and the external urethral sphincter. 30 to 40 ducts empty independently into the prostatic sinuses on the posterior aspect of the urethral lumen. The ejaculatory ducts pass almost vertically in an anteroinferior direction through the posterior aspect of the prostate to open into the prostatic urethra. Secretions from the prostate, together with secretions from the seminal vesicles, contribute to the formation of semen during ejaculation. Bulbo-urethral glands Also called Cowper's glands, are small, peashaped mucous glands situated within the deep perineal pouch. They are lateral to the membranous part of the urethra. The duct from each gland passes inferomedially through the perineal membrane, to open into the bulb of the spongy urethra at the root of the penis. Together with small glands positioned along the length of the spongy urethra, the bulbo-urethral glands contribute to lubrication of the urethra and the preejaculatory emission from the penis. 4. Urethra Urethra in females In women, the urethra is short, being about 4 cm long. Two small paraurethral mucous glands (Skene’s glands) are associated with the lower end of the urethra. Each drains via a duct that opens onto the lateral margin of the external urethral orifice. Urethra in males In men, the urethra is long, about 20 cm, bends twice along its course, and has 4 parts. The preprostatic part of the urethra is about 1 cm long, extends from the base of the bladder to the prostate, and is surrounded by the internal urethral sphincter. Urethra in males The prostatic part of the urethra is 3 to 4 cm long and is surrounded by the prostate. The lumen of the prostatic urethra is marked by a longitudinal midline fold of mucosa (the urethral crest). The depression on each side of the crest is the prostatic sinus; the ducts of the prostate empty into these two sinuses. Midway along its length, the urethral crest is enlarged to form a somewhat circular elevation (the seminal colliculus). The prostatic utricle opens onto the center of the seminal colliculus. On each side of the prostatic utricle is the opening of the ejaculatory duct. Urethra in males The membranous part of the urethra is narrow and passes through the deep perineal pouch and is surrounded by the external urethral sphincter. Urethra in males The spongy part of the urethra is surrounded by erectile tissue (the corpus spongiosum) of the penis. It is enlarged to form a bulb at the base of the penis and again at the end of the penis to form the navicular fossa The bulbourethral glands drain into the spongy part of the urethra. 5. Arteries, Veins and Nerves Arterial supply and Venous drainage The arterial blood supply to the organs of reproduction is predominantly facilitated by the anterior trunk of the internal iliac artery, which gives rise to several significant branches in both males and females. In males, these branches include the prostatic and the vesical arteries. In females, these branches include the uterine and the vaginal arteries. Venous drainage follows arterial supply, draining into the internal iliac vein. Testicular and Ovarian arteries and veins Testicular and ovarian arteries are branches of the Abdominal Aorta Left veins drain into the the Left renal artery. Right veins drain into the IVC Innervation The male and female reproductive systems are both innervated by both sympathetic and parasympathetic nerves. The sympathetic nerves originate from the thoracolumbar spinal cord (T10-L2) and travel to the reproductive organs via the hypogastric plexus. The parasympathetic nerves originate from the sacral spinal cord (S2-S4) and travel to the reproductive organs via the pelvic splanchnic nerves. Bibliography Gray’s Anatomy for Students, 4th Edition. Chapter 5.