Female Internal Genitalia PDF

Female internal genital organs Include: 1. The ovaries 2. The uterine tubes 3. The uterus 4. the vagina By Soressa A (PhD) 1. Ovaries – Are paired female gonads – One on each side of uterus – Their primary function is to produce female gamete...

Female internal genital organs Include: 1. The ovaries 2. The uterine tubes 3. The uterus 4. the vagina By Soressa A (PhD) 1. Ovaries – Are paired female gonads – One on each side of uterus – Their primary function is to produce female gamete – Produce estroid hormone (estrogen and progesterone) Dimensions : – length: 5 cm, width: 1.5 cm and thickness: 1 cm – are almond-shaped, of a greyishpink color and smooth surface before puberty – As age advances the surface becomes irregular Position: – is attached to the back of the broad ligament by the mesovarium – lies against the lateral wall of the pelvis in a depression called the ovarian fossa By Soressa A (PhD) Boundaries of ovarian fossa Anteriorly – Umbilical artery Posteriorly – the external iliac vessels above and by the internal iliac vessels behind – ureter The position of the ovary is, however, extremely variable, and it is often found hanging down in the rectouterine pouch (pouch of Douglas) During pregnancy, the enlarging uterus pulls the ovary up into the abdominal cavity. After childbirth, when the broad ligament is lax, the ovary takes up a variable position in the pelvis By Soressa A (PhD)  In a nulliparous woman the ovary has: – Two surface: medial and lateral surface – Two ends: upper( tubal) end – Lower ( uterine) end – Two borders: free and attached Ligaments of the ovary – That part of the broad ligament extending between the attachment of the mesovarium and the lateral wall of the pelvis is called the suspensory ligament of the ovary – The round ligament of the ovary, which represents the remains of the upper part of the gubernaculum, connects the lateral margin of the uterus to the ovary By Soressa A (PhD)  The suspensory ligament conveys: – the ovarian vessels – lymphatics, and nerves to and from the ovary – constitutes the lateral part of the mesovarium Round ligament of the ovary – runs within the mesovarium – is a remnant of the superior part of the ovarian gubernaculum of the fetus – connects the proximal (uterine) end of the ovary to the lateral angle of the uterus, just inferior to the entrance of the uterine tube By Soressa A (PhD) Relation: Lateral surface: – related to the peritoneum of the ovarian fossa which separate the ovary from the obturator narve and vessels Medial surface: – coverd by fimbriated end of the uterine tube Tubal end: – gives attachment to the ovarian fimbria of the tube Uterine end: – attached to the lateral angle of the uterus Free border: – which is convex and separated from the ureter by peritoneum Mesovarium ( attached) border: – attached to the back of the broad ligament by mesovarium By Soressa A (PhD) 2. Uterine Tubes (fallopian tubes, oviducts, salpinx) – Are muscular “J” tuebe – conduct the oocyte (ovum) – provide the usual site of fertilization – extend laterally from the uterine horns – open into the peritoneal cavity near the ovaries – Is approximately 10 cm  In the ideal disposition, the tubes extend long posterolaterally to the lateral pelvic walls, where they ascend and arch over – lie in the upper border of the ovaries the broad ligament,  ultrasound studies demonstrate that the mesosalpinx, in the free position of the tubes and ovaries is edges of the broad variable (dynamic) in life, and right and By Soressa A (PhD) ligaments ( left sides are often asymmetrical. The uterine tubes: – are divisible into four parts, from lateral to medial: 1. Infundibulum: the funnel-shaped distal end of the tube opens into the peritoneal cavity through the abdominal ostium bears finger-like processes knownas fimbriated the fimbriae spread over the medial surface of the ovary one large ovarian fimbria is attached to the superior pole of the ovary By Soressa A (PhD) 2. Ampulla: the widest and longest part of the tube begins at the medial end of the infundibulum Is usually site of fertilization of the oocyte By Soressa A (PhD) 3. Isthmus: the thick-walled part of the tube enters the uterine horn is the narrowest part of the tube lies just lateral to the uterus 4. Uterine part: the short intramural segment of the tube that passes through the wall of the uterus opens via the uterine ostium into the uterine cavity at the uterine horn By Soressa A (PhD) By Soressa A (PhD) Arterial supply of the ovaries and uterine Tubes The ovarian arteries: – arise from the abdominal aorta and descend along the posterior abdominal wall – At the pelvic brim, they cross over the external iliac vessels and enter the suspensory ligaments, approaching the lateral aspects of the ovaries and uterine tubes The ascending branches of the uterine arteries (branches of the internal iliac arteries), course along the lateral aspects of the uterus to approach the medial aspects of the ovaries and tubes Both the ovarian and ascending uterine arteries terminate by bifurcating into ovarian and tubal branches, which supply ovaries and uerine tubes from opposite ends anastomose with each other, providing a collateral circulation from abdominal and pelvic sources to both structures By Soressa A (PhD) By Soressa A (PhD) Venous drainage of the ovaries and uterine tubes Veins draining the ovary form a vine-like pampiniform plexus of veins in the broad ligament near the ovary and uterine tube the veins of the plexus usually merge to form a singular ovarian vein, which leaves the lesser pelvis with the ovarian artery The right ovarian vein ascends to enter the inferior vena cava the left ovarian vein drains into the left renal vein The tubal veins drain into the ovarian veins and uterine (uterovaginal) venous plexus Lymphatic drainage of the ovaries and uterine tube: The lymphatic vessels from the ovary join those from the uterine tubes and fundus and follow the ovarian blood vessels as they ascend to the right and left lumbar (caval/aortic) lymph nodes By Soressa A (PhD) Innervation of the ovaries and uterine tubes The nerve supply derives partly from the ovarian plexus, descending with the ovarian vessels, and partly from the uterine (pelvic) plexus The ovaries and uterine tubes are intraperitoneal and, therefore, are superior to the pelvic pain line Thus visceral afferent pain fibers ascend retrogradely with the descending sympathetic fibers of the ovarian plexus and lumbar splanchnic nerves to cell bodies in the T11 to L1 spinal sensory ganglia Visceral afferent reflex fibers follow parasympathetic fibers retrogradely through the uterine (pelvic) and inferior hypogastric plexuses and the pelvic splanchnic nerves to cell bodies in the S2 - S4 spinal sensory ganglia. By Soressa A (PhD) The blood supply, lymph drainage, and nerve supply of the ovary pass over the pelvic inlet and cross the external iliac vessels reach the ovary by passing through the lateral end of the broad ligament, the part known as the suspensory ligament of the ovary The vessels and nerves finally enter the hilum of the ovary via the mesovarium (Compare the blood supply and the lymph drainage of the ovary with those of the testis) By Soressa A (PhD) 3. Uterus – is a thick-walled, pear- shaped, hollow muscular organ – The non-gravid (non- pregnant) uterus usually lies in the lesser pelvis – its body lying on the urinary bladder, – and its cervix lying between the urinary bladder anteriorly and the rectum posteriorly By Soressa A (PhD)  The adult uterus is usually: anteverted (tipped anterosuperiorly relative to the axis of the vagina) anteflexed (flexed or bent anteriorly relative to the cervix) so that its mass lies over the bladder The position of the uterus changes with the degree of fullness of the bladder and rectum By Soressa A (PhD) Dimensions: is approximately 7.5 cm long, 5 cm wide, and 2 cm thick and weighs approximately 90 g. The uterus is divisible into three parts: 1. The funds: the rounded upper part lies superior to the orifices of the uterine tubes Covered with peritoneum 2. The body: lies between the layers of the broad ligament and is freely movable It has two surfaces: In the young a) vesical surface (related to the bladder) nulliparous adult, it is b) intestinal surface about 8 cm long, 5 The body is demarcated from the cervix by the isthmus of the uterus, a relatively cm wide, and 2.5 cm constricted segment, approximately 1 thick. cm long By Soressa A (PhD) 3. The cervix: is the cylindrical relatively narrow inferior third of the uterus approximately 2.5 cm long in an adult non-pregnant woman Has two parts 1. Supravaginal part: – lies between the isthmus and the vagina – the supra-vaginal part is separated: from the bladder anteriorly by loose connective tissue from the rectum posteriorly by the rectouterine pouch. 2. Vaginal part protrudes down into the vagina The rounded vaginal part: surrounds the external os of the uterus is surrounded in turn by a narrow space, the vaginal fornix By Soressa A (PhD) Uterine cavity The slit-like uterine cavity is ≈ 6 cm in length from the external os to the fundus uterine horns are the superolateral regions of the uterine cavity, where the uterine tubes enter The cavity of the uterine body: – is triangular in coronal section – but it is merely a cleft in the sagittal plane The cavity of the cervix: – the cervical canal, fusiform in shape, communicates : with the cavity of the body through the internal os with that of the vagina through the external os Before the birth of the first child, the external os is circular. In a parous woman, the vaginal part of the cervix is larger, and the external os becomes a transverse slit so that it possesses an anterior lip and a posterior lip By Soressa A (PhD) By Soressa A (PhD) The wall of the uterus: made up of three layers 1. Perimetrium:  Is the outer serous coat  consists of peritoneum supported by a thin layer of connective tissue 2. Myometrium:  the middle muscular layer  Made up of smooth muscle, which capable of distention during pregnancy  the main branches of the blood vessels and nerves of the uterus are located in this layer By Soressa A (PhD) 3. Endometrium:  the inner mucous layer  firmly adheres to the myometrium  is actively involved in the menstrual cycle, differing in structure with each stage  if conception occurs, the blastocyst becomes implanted in this layer  if conception does not occur, the inner surface of the coat is shed through menstruation. By Soressa A (PhD) By Soressa A (PhD) Relations of the uterus: Anteriorly (anteroinferiorly): – the vesicouterine pouch and superior surface of the bladder – the supravaginal part of the cervix is related to the bladder and is separated from it by only fibrous connective tissue Posteriorly: – the rectouterine pouch containing loops of small intestine – the anterior surface of rectum – only the visceral pelvic fascia uniting the rectum and uterus By Soressa A (PhD)  Laterally: – broad ligament flanking the uterine body – the fascial transverse cervical ligaments on each side of the cervix and vagina – in the transition between the two ligaments – the ureters run anteriorly slightly superior to the lateral part of the vaginal fornix and inferior to the uterine arteries, usually approximately 2 cm lateral to the supravaginal part of the cervix. By Soressa A (PhD) Ligaments of the Uterus the ligament of the ovary: attaches to the uterus posteroinferior to the uterotubal junction The round ligament of the uterus (L. ligamentum teres uteri): attaches anteroinferiorly to this junction Anterior ligament: formed by uterovesical pouch (fold) Posterior ligament: formed by rectovaginal pouch Uterosacral ligament: – the crescent fold of peritoneum which bounds the rectovaginal pouch on each side – The fold extends from the cervix to the rectum By Soressa A (PhD) Transverse cervical (cardinal) ligaments – are fibromuscular condensations of pelvic fascia that pass to the cervix and the upper end of the vagina from the lateral walls of the pelvis Pubocervical ligaments consist of two firm bands of connective tissue that pass to the cervix from the posterior surface of the pubis They are positioned on either side of the neck of the bladder, to which they give some support (pubovesical ligaments) Sacrocervical Ligaments consist of two firm fibromuscular bands of pelvic fascia that pass to the cervix and the upper end of the vagina from the lower end of the sacrum They form two ridges, one on either side of the rectouterine pouch (pouch of Douglas) By Soressa A (PhD) The broad ligament: is a double layer of peritoneum (mesentery) extends from the sides of the uterus to the lateral walls and floor of the pelvis assists in keeping the uterus in position. Has two layers that are continuous with each other at a free edge surrounding the uterine tube Laterally, the peritoneum of the broad ligament is prolonged superiorly over the vessels as the suspensory ligament of the ovary Between the layers of the broad ligament on each side of the uterus: – the ligament of the ovary lies posterosuperiorly – the round ligament of the uterus lies anteroinferiorly – the uterine tube lies in the anterosuperior free border of the broad ligament, within a small mesentery called the mesosalpinx. By Soressa A (PhD) By Soressa A (PhD)  the ovary lies within a small mesentery called the mesovarium on the posterior aspect of the broad ligament. The largest part of the broad ligament, inferior to the mesosalpinx and mesovarium, which serves as a mesentery for the uterus itself, is the mesometrium. By Soressa A (PhD)  At the base of the broad ligament, the uterine artery crosses the ureter Contents of each broad ligament: 1. the uterine tube in its upper free border 2. the round ligament of the ovary and the round ligament of the uterus. both represent the remains of the gubernaculum. 3. The uterine and ovarian blood vessels, lymph vessels, and nerves 4. The epoophoron - a vestigial structure that lies in the broad ligament above the attachment of the mesovarium. 1. It represents the remains of the mesonephros (Fig. 7-19). 5. The paroophoron - also a vestigial structure that lies in the broad ligament just lateral to the uterus. It is a mesonephric remnant By Soressa A (PhD) A. Coronal section of the pelvis showing the uterus, broad ligaments, and right ovary on posterior view. The left ovary and part of the left uterine tube have been removed for clarity B. Uterus on lateral view. Note the structures that lie within the broad ligament. Note that the uterus has been retroverted into the plane of the vaginal lumen in both diagrams. By Soressa A (PhD)  The round ligament of the uterus: – which represents the remains of the lower half of the gubernaculum – extends between the superolateral angle of the uterus, through the deep inguinal ring and inguinal canal, to the subcutaneous tissue of the labium majus – it helps keep the uterus anteverted (tilted forward) and anteflexed (bent forward) but is considerably stretched during pregnancy By Soressa A (PhD) Support of the uterus The uterus is a dense structure located in the center of the pelvic cavity The principal supports of the uterus holding it in this position are both passive and active or dynamic Dynamic support of the uterus is provided by the pelvic diaphragm – Its tone during sitting and standing and active contraction during periods of increased intra-abdominal pressure (sneezing, coughing, etc.) is transmitted through the surrounding pelvic organs and the endopelvic fascia in which they are embedded. Passive support of the uterus: is provided by its position – the way in which the normally anteverted and anteflexed uterus rests on top of the bladder – When intra-abdominal pressure is increased, the uterus is pressed against the bladder By Soressa A (PhD) The cervix: is the least mobile part of the uterus because of the passive support provided by attached condensations of endopelvic fascia (ligaments), which may also contain smooth muscle – Transverse cervical (cardinal) ligaments extend from the cervix and lateral parts of the fornix of the vagina to the lateral walls of the pelvis. – Uterosacral ligaments pass superiorly and slightly posteriorly from the sides of the cervix to the middle of the sacrum; they are palpable during a rectal examination. Together these passive and active supports keep the uterus centered in the pelvic cavity and resist the tendency for the uterus to fall or be pushed through the vagina By Soressa A (PhD) By Soressa A (PhD)  Position of uterus in relation to vagina – The uterus is usually not exactly median. – Its funds is slightly tilted to the right – Correspondingly the cervix and upper part of the vagina are slightly tilted to the left – The body of the uterus bends forwards under the weight of the intestine – this bend occurs at isthmus. Therefore, it is said that the body is ante flexed on the cervix – The whole uterus forms nearly at right angle with the long axis of the vagina – Therefor this is said that the uterus is anteverted on the vagina By Soressa A (PhD) Anteverted position of the uterus. anteflexed position of the uterus. By Soressa A (PhD) 1. Uterus in the Child – The fundus and body of the uterus remain small until puberty – they enlarge greatly in response to the estrogens secreted by the ovaries during puperty 2. Uterus After Menopause – After menopause, the uterus atrophies and becomes smaller and less vascular – These changes occur because the ovaries no longer produce estrogens and progesterone. By Soressa A (PhD) 3. Uterus in Pregnancy – During pregnancy, the uterus becomes: greatly enlarged as a result of the increasing production of estrogens and progesterone, first by the corpus luteum of the ovary later by the placenta. by the third month the fundus rises out of the pelvis by the ninth month it has reached the xiphoid process The increase in size is largely a result of hypertrophy of the smooth muscle fibers of the myometrium, although some hyperplasia takes place. By Soressa A (PhD) Examination of the Uterus The size and disposition of the uterus may be examined by bimanual palpation Two fingers of the right hand are passed superiorly in the vagina, while the other hand is pressed inferoposteriorly on the pubic region of the anterior abdominal wall The size and other characteristics of the uterus can be determined in this way (e.g., whether the uterus is in its normal anteverted position) When softening of the uterine isthmus occurs (Hegar sign), the cervix feels as though it were separated from the body. Softening of the isthmus is an early sign of pregnancy The uterus can be further stabilized through rectovaginal examination, which is used if examination via the vagina alone does not yield clear findings By Soressa A (PhD) By Soressa A (PhD) Disposition of the uterus and uterine prolapse When intra-abdominal pressure is increased, the normally anteverted and anteflexed uterus is pressed against the bladder However, the uterus may assume other dispositions, including excessive anteflexion, anteflexion with retroversion, and retroflexion with retroversion Instead of pressing the uterus against the bladder, increased intra- abdominal pressure tends to push the retroverted uterus, a solid mass positioned upright over the vagina (a flexible, hollow tube), into or even through the vagina A retroverted uterus will not necessarily prolapse but is more likely to do so, and pregnancies involving a retroverted uterus are considered to be higher risk pregnancies The situation is exacerbated in the presence of a disrupted perineal body or with atrophic (relaxed) pelvic floor ligaments and muscles By Soressa A (PhD) Lifetime Changes in Anatomy of the Uterus The uterus is possibly the most dynamic structure in human anatomy At birth, – the uterus is relatively large – has adult proportions (body to cervical ratio = 2:1) Several weeks postpartum (after childbirth), – childhood dimensions and proportions are obtained: the body and cervix are approximately of equal length (body to cervical ratio = 1:1), with the cervix being of greater diameter (thickness) The cervix remains relatively large (≈50% of total uterus) throughout childhood By Soressa A (PhD)  During puberty, – the uterus (especially its body) grows rapidly in size, once again assuming adult proportions Postpubertal, premenopausal, non-pregnant woman, – the body is pear shaped – the thick-walled – superior two thirds of the uterus lies within the pelvic cavity During menopause, – the uterus (again, especially the body) decreases in size Postmenopause, – the uterus is involuted and regresses to a markedly smaller size, once again assuming childhood proportions By Soressa A (PhD) By Soressa A (PhD) By Soressa A (PhD) Blood Supply Arteries: mainly from the uterine artery, a branch of the internal iliac artery – It reaches the uterus by running medially in the base of the broad ligament – It crosses above the ureter at right angles and reaches the cervix at the level of the internal os – The artery then ascends along the lateral margin of the uterus within the broad ligament and ends by anastomosing with the ovarian artery, which also assists in supplying the uterus. – The uterine artery gives off a small descending branch that supplies the cervix and the vagina. Venous drainage: The uterine vein follows the artery and drains into the internal iliac vein. By Soressa A (PhD) Lymph Drainage The lymph vessels from the fundus of the uterus accompany the ovarian artery and drain into the para- aortic nodes at the level of the first lumbar vertebra. The vessels from the body and cervix drain into the internal and external iliac lymph nodes. A few lymph vessels follow the round ligament of the uterus through the inguinal canal and drain into the superficial inguinal lymph nodes. Nerve Supply Sympathetic and parasympathetic nerves from branches of the inferior hypogastric plexuses By Soressa A (PhD) Hysterectomy is performed through the lower anterior abdominal wall or through the vagina Because the uterine artery crosses anterior to the ureter near the lateral fornix of the vagina, the ureter is in danger of being inadvertently clamped or severed when the uterine artery is tied off during a hysterectomy The point of crossing of the artery and the ureter is approximately 2 cm superior to the ischial spine By Soressa A (PhD)  Laparoscopic Examination of Pelvic Viscera – Laparoscopy involves inserting a laparoscope into the peritoneal cavity through a small incision below the umbilicus. By Soressa A (PhD) 4. Vagina a musculomembranous tube is about 7 - 9 cm long runs upward and backward from the vulva to the uterus extends from the cervix of the uterus to the vestibule, the cleft between the labia minora The vestibule contains: the vaginal and external urethral orifices the openings of the two greater vestibular glands Serves as a canal for menstrual fluid. Forms the inferior part of the pelvic (birth) canal Receives the penis and ejaculate during sexual intercourse The superior end of the vagina surrounds the cervix By Soressa A (PhD)  Communicates : – superiorly with the cervical canal through external os – inferiorly with the vestibule through vaginal orffice Has two walls 1. Anterior wall is pierced by the cervix, which projects downward and backward into the vagina 2. Posterior walls, which are normally in apposition Has two halvies: The upper half – located superior to the pelvic diaphragm - also called pelvic part The lower half – below pelvic diaphragm - is perineal part By Soressa A (PhD) The vagina: is usually collapsed (H-shaped in cross section) so that its anterior and posterior walls are in contact, except at its superior end where the cervix holds them apart The vaginal fornix (the recess around the cervix) has: – anterior, posterior, and the two lateral parts – The posterior vaginal fornix is the deepest part and is closely related to the rectouterine pouch By Soressa A (PhD) Four muscles compress the vagina and act as sphincters: – Pubovaginalis – external urethral sphincter – urethrovaginal sphincter – bulbospongiosus By Soressa A (PhD) Relations of the vagina Anteriorly: Its upper half the fundus of the urinary bladder Its lower half Urethra Posteriorly (inferior to superior): The upper third of the vagina is related to the rectouterine pouch (pouch of Douglas) its middle third to the ampulla of the rectum The lower third is related to the perineal body, which separates it from the anal canal. By Soressa A (PhD) Laterally: in its upper part is related to the ureter its middle part is related to the anterior fibers of the levator ani, as they run backward to reach the perineal body and hook around the anorectal junction. Contraction of the fibers of levator ani compresses the walls of the vagina together. In its lower part is related to the urogenital diaphragm and the bulb of the vestibule By Soressa A (PhD) Arterial supply: The arteries supplying: the superior part of the vagina – derive from the uterine arteries middle and inferior parts of the vagina: – derive from the vaginal and internal pudendal arteries By Soressa A (PhD) Venous drainage: The vaginal veins form vaginal venous plexuses: – along the sides of the vagina – within the vaginal mucosa These veins are continuous: – with the uterine venous plexus as the uterovaginal venous plexus – drain into the internal iliac veins through the uterine vein – This plexus also communicates with the vesical and rectal venous plexuses. By Soressa A (PhD) Lymphatic drainage: The vaginal lymphatic vessels drain from the parts of the vagina as follows: Superior part: → to the internal and external iliac lymph nodes. Middle part: → to the internal iliac lymph nodes. Inferior part: → to the sacral and common iliac nodes. External orifice: → to the superficial inguinal lymph nodes By Soressa A (PhD) Distension of the Vagina The vagina can be markedly distended, particularly in the region of the posterior part of the fornix For example, distension of this part allows palpation of the sacral promontory during a pelvic examination and accommodates the erect penis during intercourse. The vagina is especially distended by the fetus during parturition, particularly in an AP direction when the fetus's shoulders are delivered. Lateral distension is limited by the ischial spines, which project posteromedially, and the sacrospinous ligaments extending from these spines to the lateral margins of the sacrum and coccyx. The birth canal is thus deep anteroposteriorly and narrow transversely at this point, causing the fetus's shoulders to rotate into the AP plane By Soressa A (PhD) The interior of the vagina can be distended for examination using a vaginal speculum (Fig. B3.4). The cervix, ischial spines, and sacral promontory can be palpated with the digits in the vagina and/or rectum (manual pelvic examination). By Soressa A (PhD) Digital examination through the vagina Because of its relatively thin, distensible walls and central location within the pelvis, the cervix, ischial spines, and sacral promontory can be palpated with the digits in the vagina and/or rectum (manual pelvic examination) Pulsations of the uterine arteries may also be felt through the lateral parts of the fornix, as may irregularities of the ovaries, such as cysts The interior of the vagina can be distended for examination using a vaginal speculum (Fig. B3.4). The cervix, ischial spines, and sacral promontory can be By Soressa A (PhD) palpated with the digits in the vagina and/or rectum (manual pelvic examination).  The interior of the vagina can be distended for examination using a vaginal speculum (Fig. B3.4). The cervix, ischial spines, and sacral promontory can be palpated with the digits in the vagina and/or rectum (manual pelvic examination). By Soressa A (PhD) Vaginal fistulae Because of the close relationship of the vagina to adjacent pelvic organs, obstetrical trauma during long and difficult labor may result: – in weaknesses – Necrosis – or tears in the vaginal wall and sometimes beyond – These may form or subsequently develop into open communications (fistulas) between the vaginal lumen and that of the adjacent bladder, urethra, rectum, or perineum – Urine enters the vagina from both vesicovaginal and urethrovaginal fistulas – but the flow is continuous from the former and occurs only during micturition from the latter – Fecal matter may be discharged from the vagina when there is a rectovaginal fistula By Soressa A (PhD) By Soressa A (PhD) Rectum – is about 13 cm long – is the pelvic part of the alimentary tract – is continuous: proximally with the sigmoid colon distally with the anal canal – The rectosigmoid junction lies anterior to the S3 vertebra At this point, the teniae of the sigmoid colon spread out to form a continuous outer longitudinal layer of smooth muscle the fatty omental appendices are discontinued – follows the curve of the sacrum and coccyx, forming the sacral flexure of the rectum – ends anteroinferior to the tip of the coccyx, where it continous as anal canal, immediately before a sharp posteroinferior angle (the anorectal flexure of the anal canal) By Soressa A (PhD) – anorectal flexure has roughly 80 degree is an important mechanism for fecal continence, by the tonus of the puborectalis muscle – with the flexures of the rectosigmoid junction superiorly and the anorectal junction inferiorly, the rectum has an S shape when viewed laterally By Soressa A (PhD)  The rectum – Has three sharp lateral flexures (superior, intermediate, and inferior) are apparent when the rectum is viewed anteriorly. – The flexures are formed in relation to three internal infoldings (transverse rectal folds): two on the left one on the right side The folds overlie thickened parts of the circular muscle layer of the rectal wall – The dilated terminal part of the rectum is the ampulla and supported by the pelvic diaphragm – The ampulla receives and holds an accumulating fecal mass until it is expelled during defecation – The ability of the ampulla to relax to accommodate the initial and subsequent arrivals of fecal material is another essential element of maintaining Byfecal continence Soressa A (PhD) Peritoneum: covers the anterior and lateral surfaces of the superior third of the rectum only the anterior surface of the middle third no surface of the inferior third covered by peritoneum In males, the peritoneum reflects from the rectum to the posterior wall of the bladder forms the floor of the rectovesical pouch In females, the peritoneum reflects from the rectum to the posterior part of the fornix of the vagina forms the floor of the rectouterine pouch In both sexes, lateral reflections of peritoneum from the superior third of the rectum form pararectal fossae which permit the rectum to distend as it fills with feces. By Soressa A (PhD) By Soressa A (PhD)  The rectum lies posteriorly against: – the inferior three sacral vertebrae and the coccyx – anococcygeal ligament – median sacral vessels – and inferior ends of the sympathetic trunks and sacral plexuses In males, the rectum is related anteriorly : – to the fundus of the urinary bladder – terminal parts of the ureters, ductus deferentes – seminal glands, and prostate – The rectovesical septum lies between the fundus of the bladder and the ampulla of the rectum and is closely associated with the seminal glands and prostate By Soressa A (PhD)  In females, the rectum is related anteriorly to: – the vagina and is separated from the posterior part of the fornix and the cervix by the rectouterine pouch – Inferior to this pouch, the weak rectovaginal septum separates the superior half of the posterior wall of the vagina from the rectum By Soressa A (PhD) Arterial supply of the rectum From the three sources: The superior rectal artery: – the continuation of the inferior mesenteric artery – supplies the proximal part of the rectum The right and left middle rectal arteries: – usually arising from the inferior vesical arteries – supply the middle and inferior parts of the rectum The inferior rectal arteries: – arising from the internal pudendal arteries – supply the anorectal junction and anal canal Anastomoses between these arteries provide potential collateral circulation. By Soressa A (PhD) By Soressa A (PhD) Venous drainage of the rectum Blood from the rectum drains through the superior, middle, and inferior rectal veins Anastomoses occur between the portal and systemic veins in the wall of the anal canal Because the superior rectal vein drains into the portal venous system and the middle and inferior rectal veins drain into the systemic system, these anastomoses are clinically important areas of portacaval anastomosis The submucosal rectal venous plexus surrounds the rectum and communicates with: – the vesical venous plexus in males – the uterovaginal venous plexus in females By Soressa A (PhD) The rectal venous plexus consists of two parts: the internal rectal venous plexus just deep to the mucosa of the anorectal junction the subcutaneous external rectal venous plexus external to the muscular wall of the rectum Although these plexuses bear the term rectal, they are primarily anal in terms of location, function, and clinical significance Lymphatic drainage: Lymphatic vessels from the superior half of the rectum pass to the pararectal lymph nodes (located directly on the muscle layer of the rectum) and then ascend to the inferior mesenteric lymph nodes, either via sacral lymph nodes or more directly passing through nodes along the superior rectal vessels The inferior mesenteric nodes drain into the lumbar (caval/aortic) lymph nodes. Lymphatic vessels from the inferior half of the rectum drain directly to sacral lymph nodes or, especially from the distal ampulla, follow the middle rectal vessels to drain into the internal iliac lymph nodes By Soressa A (PhD) Innervation of the rectum The nerve supply to the rectum is from: – the sympathetic and parasympathetic systems (Fig. 3.36). – The sympathetic supply is from the lumbar spinal cord, conveyed via lumbar splanchnic nerves and the hypogastric/pelvic plexuses and through the peri-arterial plexus of the inferior mesenteric and superior rectal arteries – The parasympathetic supply is from the S2 - S4 spinal cord level, passing via the pelvic splanchnic nerves and the left and right inferior hypogastric plexuses to the rectal (pelvic) plexus – Because the rectum is inferior (distal) to the pelvic pain line, all visceral afferent fibers follow the parasympathetic fibers retrogradely to the S2 - S4 spinal sensory ganglia N.B. the rectum is only sensitive to stretch By Soressa A (PhD) The end of the pelvis By Soressa A (PhD)