Anatomy of Uterus and physiology of Uterus

Anatomy and physiology

1. ANATOMY AND PHYSIOLOGY OF UTERUS - DR.SANDHIYA.K 1 ST YEAR PG RESIDENT Svmch&rc

2. TABLE OF CONTENTS ANATOMY OF UTERUS : EMBRYOLOGY OF UTERUS PARTS OF UTERUS MEASUREMENTS COMMUNICATIONS AND RELATIONS CAVITY STRUCTURES PERITONEUM IN RELATION TO UTERUS BLOOD SUPPLY LYMPHATICS AND NERVE SUPPLY

3. EMBRYOLOGY OF UTERUS The urogenital tract is functionally divided into the urinary system and genital system These b oth develop from intermediate mesoderm During initial embryo folding, this intermediate mesoderm develops along each side of the primitive abdominal aorta and is called the urogenital ridge. T he urogenital ridge further divides into the nephrogenic ridge and the genital ridge, also called the gonadal ridge.

4. At 60 days of gestation , Nephrogenic ridge give rise to Mesonephric Kidney and MESONEPHRIC DUCT (WOLFFIAN DUCT ) . At 6 th week of gestation paired PARAMESONEPHRIC DUCT (MULLERIAN DUCT ) develops due to invagination of coelomic epithelium and grow alongside mesonephric duct . In female , a lack of Antimullerian hormone allows mullerian ducts to persist . At 10 weeks of gestation the distal portion of mullerian ducts fuse in the midline even before they reach urogenital sinus (Cloaca divided by urorectal septum give rise to rectum and urogenital sinus ) The fused ducts form uterovaginal canal and then inserts into urogenital sinus at muller tubercle By 12 weeks mesonephric duct regress due to Lack of testosterone . Uterine corpus and cervix differentiates and the midline septum undergoes dissolution to form uterine cavity .this is completed by 20 weeks . The unfused cepalad portion of mullerian duct forms Fallopian tube . Vagina – upper 2/3 : From fused Mullerian duct distal 1/3 : sinovaginal bulb { evagination from urogenital sinus }

5. DEVELOPMENT OF FEMALE REPRODUCTIVE SYSTEM EMBRYOLOGY OF UTERUS AND VAGINA

6. REMNANTS OF MULLERIAN DUCT IN MALES REMNANTS OF WOLFFIAN IN FEMALES APPENDIX OF TESTIS EPO OOPHORON AND PARA OOPHORON PROSTATIC UTRICLE GARTNER’S DUCT CLINICAL ASPECTS : Abnormalities of the uterus may be congenital or acquired and present with menstrual dysfunction, pelvic pain , infertility or early pregnancy loss . Developmental anomalies of mullerian duct is termed Mullerian anomalies .

7. CLASSIFICATION OF MULLERIAN ANOMALIES

8. INTRODUCTION : Uterus is a fibromuscular hollow organ situated in pelvis between the bladder in front and the rectum behind. Its long axis is horizontal if the bladder is empty in the erect posture. COMMUNICATIONS OF UTERUS : Superiorly – Fallopian tube Inferiorly – vagina SIZE AND SHAPE OF UTERUS : Shape – Pear shape Length – 8 cm Breadth – 5 cm Thickness –1.25 cm Weight – Nonpregnant :70 g Pregnant : 1100 g {term} Volume – Nonpregnant :10 ml Pregnant : 5000ml

9. PARTS OF UTERUS Body Isthmus Cervix BODY :It is further divided into Fundus and body proper and cornua of uterus . Fundus – part that lies above the uterine tubes Body proper – triangular and lies between uterine tube and isthmus Cornua of uterus – superolateral angles of body of uterus project outwards from junction of fundus and body . Anterior surface of body – covered by peritoneum up to isthmus where it is reflected on to the upper surface of urinary bladder forming UTEROVESICAL POUCH , Posterior surface of body – covered by peritoneum which extends downward upto posterior fornix of vagina where it is reflected on the anterior aspect of rectum forming RECTOUTERINE POUCH (POUCH OF DOUGLAS ).

10. Right and left lateral border – it is related to uterine artery and is non peritoneal and provides attachment to Broad ligament of uterus . Round ligament of uterus is attached anteroinferior to the tube. Ligament of ovary is attached posteroinferior to tube .

11. ISTHMUS : Constricted part between uterus and cervix Measures about 0,5 cm Limited above by anatomical internal os and below by histological internal os CERVIX : It is the lower cylindrical part. Measures about 2.5 cm Its lower part projects into the upper part of the vagina through its anterior wall. Thus, the cervix is divided into two parts: (a) upper supravaginal part. (b) lower vaginal part.

12. The cavity of uterus is small in comparison to its size due to its thick muscular wall. It is divided into two parts: cavity of the body cavity of the cervix. Cavity of the Body (Uterine Cavity Proper) : It is a triangular in coronal section. The apex of this cavity is continuous below with the cervical canal through internalos . The implantation commonly occurs in the upper part of its posterior wall. It is slit in sagittal section, because the uterus is compressed anteroposteriorly and its anterior and posterior walls are almost in contact. CAVITY OF UTERUS :

13. CAVITY OF CERVIX (cervical canal ): It is a spindle-shaped canal, being broader in the middle and narrow at the ends. It communicates anterosuperiorly with the cavity of body of uterus through internal os and inferiorly with the cavity of vagina through external os In nulliparous women ,the external os is small and circular, whereas in multiparous women,the external os is large and transverse, and presents anterior and posterior lips . Cavity of uterine body measures about 3.5cm Cavity of cervix measure 2.5 cm Normal length of uterine cavity is usually 6.5 – 7 cm

14. Normal Position And Axes Of The Uterus: Normally the uterus lies in position of anteversion and anteflexion. Anteversion : The long axis of the cervix is normally bent forward on the long axis of vagina forming an angle of about 90°. This position is called the position of anteversion. Anteflexion : The long axis of the body of uterus is bent forward at the level of isthmus (internal os ) on the long axis of cervix forming an angle of 170°. This position of the uterus is known as anteflexion.

15. ANTEVERSION : Is maintained by forward pull on fundus by traction of round ligament . Backward pull on cervix by traction of uterosacral ligament .

16. IMPLICATIONS OF RETROVERTED UTERUS : Menstrual irregularities Chronic pelvic pain Infertility

17. RELATIONS OF UTERUS : RELATIONS B ody of uterus Supravaginal portion of cervix Vaginal portion of cervix ANTERIORLY Posterior wall of uterovesical pouch Separated from base of bladder by loose areolar tissue Anterior fornix of vagina POSTERIORLY Anterior wall of rectouterine pouch containing coils of intestine Rectouterine pouch with coils of intestine Posterior fornix of vagina

18. RELATIONS B ody of uterus Supravaginal portion of cervix Vaginal portion of cervix Laterally Double fold of peritoneum of broad ligament between which uterine artery ascends up Attachment of mackenrodt ‘s ligament 1.5 cm away at the level of internal os little nearer on the left side is the crossing of the uterine artery and ureter Attachment of mackenrodt’s ligament And is related to lateral vaginal fornix

19. BROAD LIGAMENT MACKENDROTS LIGAMENT

20. The uterine artery arises from the internal iliac artery, anteriorly. Partly the uterine artery passes, medially, through the base of the broad ligament of uterus before bifurcating at the isthmus level . The ascending branch travels in parallel along the side of the uterus and fallopian tubes, following a U path and gives coil-shaped branches . The ascending branch of the uterine artery anastomoses to the ovarian artery. The descending part supplies the cervix and vagina , anastomosing with the vaginal arteries and the inferior rectal arteries . The uterine artery crosses the ureter superiorly at the level of the lateral part of the uterine cervix below the isthmic part of the uterus, explaining why the ureter is at greater risk of injury during pelvic and gynecologic surgeries. RELATION OF UTERINE ARTERY AND URETER (WATER UNDER THE BRIDGE)

21. SITE OF INJURY PROCEDURE SURGERY PELVIC BRIM CLAMPING OF INFUNDIBULO PELVIC LIGAMENTS HYSTERECTOMY WITH REMOVAL OF OVARIES OVARIOTOMY BROAD LIGAMENT UTERINE ARTERY LIGATION HYSTERECTOMY TO COMBAT OR PREVENT HEMORRHAGE CARDINAL LIGAMENT CLAMPING OF CARDINAL LIGAMENT DISSECTION OF URETERIC TUNNEL HYSTERECTOMY RADICAL HYSTERECTOMY UPPER VAGINA CLAMPING OF VAGINAL ANGLE HYSTERECTOMY BIFURCATION OF COMMON ILIAC INTERNAL ILIAC ARTERY LIGATION TO COMBAT HEMORRHAGE

22. STRUCTURES/LAYERS OF UTERUS : Body — The wall consists of three layers from outside inwards: — Parametrium : It is the serous coat which invests the entire organ except on the lateral borders. Th e peritoneum is intimately adherent to the underlying muscles. — Myometrium : It consists of thick bundles of smooth muscle fibers held by connective tissues and are arranged in various directions. During pregnancy, however, three distinct layers can be identified—outer longitudinal, middle interlacing and the inner circular. . Clinical aspects : Apposition of 2 double curve muscle fibres give the figure of 8 form and it is called as living ligatures and hemostasis is achieved as the arterioles pass through intermediate interlacing fibers of myometrium are clamped during uterine contraction .

23. — Endometrium : Th e mucous lining of the cavity is called endometrium. As there is no submucous layer , the endometrium is directly opposed to the muscle coat . It consists of lamina propria and surface epithelium. The surface epithelium is a single layer of ciliated columnar epithelium. Th e lamina propria contains stromal cells, endometrial glands, vessels and nerves. The glands are simple tubular and lined by mucus secreting non–ciliated columnar epithelium which penetrate the stroma and sometimes even enter the muscle coat. The endometrium is changed to decidua during pregnancy

24. CLINICAL ASPECTS :

25. Cervix — The cervix is composed mainly of fibrous connective tissues. The smooth muscle fibers average 10–15%. Only the posterior surface has got peritoneal coat. Mucous coat lining the endocervix is simple columnar with basal nuclei and that lining the gland is non-ciliated secretory columnar cells. The vaginal part of the cervix is lined by stratified squamous epithelium. The squamocolumnar junction is situated at the external os .

26. CLINICAL ASPECTS : The original squamous epithelium is derived from the epithelium of urogenital sinus and begins at the vulvovaginal line. It lines the vagina and the ectocervix, whereas the endocervix is lined by the columnar epithelium. The location of squamocolumnar junction in relation to the external os depends on the age, hormonal status, oral contraceptive use, pregnancy and birth trauma. Prior to puberty, the original squamocolumnar junction is located at or very close to the external os . During the reproductive years, the female genital tract remains under the influence of oestrogen resulting in elongation of the endocervical canal thereby everting the columnar lining of the endocervical canal on to the ectocervix. This shifts the original squamocolumnar junction away from the external os . The everted columnar epithelium under the influence of vaginal acidity eventually gets destroyed and is replaced by the metaplastic squamous epithelium. Thus, a new squamocolumnar junction is formed between the newly formed metaplastic squamous epithelium and the columnar epithelium. As the women progresses towards menopause, the location of new squamocolumnar epithelium moves on the ectocervix towards the external os The area between the original and new squamocolumnar junction is known as the transformation zone.

27. BLOOD SUPPLY OF UTERUS : ARTERIAL SUPPLY VENOUS DRAINAGE LYMPHATIC DRAINAGE

28. ARTERIAL SUPPLY : teries . The uterus is supplied mainly by two uterine arteries and partly by two ovarian arteries. The uterine artery is a branch of anterior division of internal iliac artery. It crosses the ureter from above lateral to the cervix above the lateral to the fornix of the vagina. Then it ascends along the side of the uterus. At the superolateral angle of uterus it turns laterally, runs along the uterine tube, and terminates by anastomosing with the ovarian artery .

29. BRANCHES OF UTERINE ARTERY : ASCENDING BRANCH DESCENDING BRANCH Ascends up on the lateral vaginal wall in a tortuous manner and anastomose with tubal branch of ovarian artery . Descends and gives off descending cervical branch and supplies cervix and vagina Further small branches of uterine artery Arcuate artery Radial artery Basal artery Spiral artery

30. CLINICAL ASPECTS : VESSELS LIGATED IN POSTPARTUM HEMORRHAGE: Uterine artery ligation Branch of ovarian artery Anterior division of internal iliac artery VENOUS DRAINAGE : Veins form a plexus in the base of broad ligament and communicate with vesical and rectal plexus and finally drain inti internal iliac veins.

31. The lymphatic drainage of the uterus is clinically important because uterine cancer spreads through lymphatics. 1. From fundus and upper part of the body : most of the lymphatics drain into pre- and paraaortic Lymph nodes along the ovarian vessels. However, a few lymphatic vessels from the lateral angles of the uterus drain into superficial inguinal lymph nodes along the round ligaments of the uterus. 2. From the lower part of the body : the lymph vessels drain into external iliac nodes via broad ligament. 3 . From cervix : on each side the lymph vessels drain in three directions: a) Laterally, the lymph vessels drain into external iliac and obturator nodes by passing parametric tissue, few of these vessels are intercepted by paracervical nodes. b) Posterolaterally , the lymph vessels drain into internal iliac nodes by passing along the uterine vessels. c) Posteriorly, the lymph vessels drain into sacral nodes by passing along the uterosacral ligaments .

32. NERVE SUPPLY : The uterus is richly innervated by both sympathetic and parasympathetic fibres. 1. The sympathetic fibres are derived from T12–L2 spinal segments. The sympathetic fibres cause uterine contraction and vasoconstriction.Sensory fibers in T11 and T12 roots carry pain sensation from the uterus . 2. The parasympathetic fibres are derived from S2–S4 spinal segments. The parasympathetic fibres inhibit the uterine muscles and cause vasodilatation.sensory fibers from cervix and upper vagina pass through S2,S3,S4 and from lower vagina through pudendal nerve .

33. CLINICAL ASPECTS : Pudendal nerve block : landmark –ISCHIAL SPINE Can be used for second satge of labour Epidural analgesia : Ideal level – T10 Can be given even in latent 1 st stage of labour Beta agonist causes uterine relaxation and used as a tocolytics Examples : Ritodrine Terbutaline

34. LIGAMENTS OF UTERUS : The ligaments of the uterus are classified into two types: false and true. The false ligaments are peritoneal folds whereas the true ligaments are fibromuscular bands. The false ligaments do not provide support to the uterus while true ligaments provide support to the uterus

35. SUPPORTS OF UTERUS : PRIMARY SUPPORT SECONDARY SUPPORT 1. Broad ligaments . 2. Uterovesical fold of peritoneum. 3. Rectovaginal fold of peritoneum 1. Muscular (a) Pelvic diaphragm. (b) Perineal body. (c) Urogenital diaphragm gm 2 . Visceral (a) Urinary bladder. (b) Vagina. (c) Uterine axis 3. Fibromuscular (a) Transverse cervical ligaments (of Mackenrodt ). (b) Pubocervical ligaments. (c) Uterosacral ligaments. (d) Round ligaments of the uterus

36. BROAD LIGAMENT : Divides pelvic cavity into • Anterior compartment for bladder • Posterior compartment for rectum and sigmoid colon SUBDIVISIONS : Meso-salpinx Mesovarium Mesometrium Suspensory ligament of ovary

37. ROUND LIGAMENT : Fibromuscular band 10-12 cm Extent – cornu of uterus through inguinal canal splits into fibrous threads and attaches to labia majora . DEVELOPMENTALLY REMNANT OF DISTAL PART OF GUBERNACULAM OF OVARY PULLS FUNDUS FORWARD

38. UTEROSACRAL LIGAMENT : Condensation of endopelvic fascia Extend – back of cervix to periosteum of sacrum Pulls cervix backwards

39. MACKENRODT’S LIGAMENT : Fan shaped fibromuscular abnd Extent – cervicovaginal junction to lateral pelvic wall Keep cervix in median position and prevent downward displacement of uterus

40. PUBOCERVICAL LIGAMENT : Connect anterior surface of cervix to inner surface of pubic symphysis Keep the cervix in midline

41. Clinical aspects: 1.PROLAPSE OF UTERUS : P elvic organ prolapse is defined as the protrusion or herniation of pelvic organs into or out of the vagina that occurs due to failure of anatomical supports .

42. PHYSIOLOGY OF UTERUS

43. MENSTRUAL CYCLE The "typical" menstrual cycle is 28 ± 7 days with menstrual flow lasting 4 ± 2 days and blood loss averaging 20 to 60 mL.

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