MATERNAL ANATOMY External and Internal Generative Organs

FEU-NRMF Department of Obstetrics and Gynecology

ANTERIOR ABDOMINAL WALL • confines abdominal viscera • stretches to accommodate the expanding uterus • provides surgical access to the internal reproductive organs

ANTERIOR ABDOMINAL WALL

ANTERIOR ABDOMINAL WALL

Skin • LANGER LINES • describe the orientation of dermal fibers • In the abdomen: • Transversely arranged

• vertical skin incisions • more tension, wider scars

• low transverse incisions (Pfannenstiel) • follow Langer lines; superior cosmetic results

Subcutaneous Layer Camper’s fascia › Superficial › predominantly fatty layer

Scarpa’s fascia › Deeper › more membranous layer  These are not discrete layers but instead represent a continuum of the subcutaneous tissue layer.

Rectus Sheath

• fibrous aponeuroses of the external oblique, internal oblique, and transversus abdominis muscles in the midline

Arcuate Line Cephalad- aponeuroses invest the rectus abdominis bellies above and below

Caudal- all aponeuroses lie anterior to the rectus abdominis muscle, and only the thin transversalis fascia and peritoneum lie beneath.

Blood Supply

Blood Supply A. Femoral Artery Branches arteries – supply the skin and subcutaneous layers of the anterior abdominal wall and mons pubis › superficial epigastric › superficial circumflex iliac › external pudendal

B. External Iliac Artery Branches - supply the muscles and fascia of the anterior abdominal wall › inferior "deep" epigastric vessels › deep circumflex iliac vessels-.

Hesselbach triangle Boundaries:  Inferiorly: inguinal ligament  Medially: lateral border of the rectus muscles  Laterally: inferior epigastric vessels.

Hesselbach triangle CLINICAL SIGNIFICANCE: Direct hernias-

involves the Hesselbach triangle Indirect hernias-

involves the deep inguinal ring

Anterior Abdominal Wall Innervation  Intercostal nerves (T7-11)  Subcostal nerve (T12)  Iliohypogastric nerve- skin over suprapubic area  Ilioinguinal nerves (L1)› skin of the lower abdominal wall › upper portion of the labia majora › medial portion of the thigh  T10 dermatome- approximates the level of the umbilicus.

Clinical Significance ILIOINGUINAL AND ILIOHYPOGASTRIC NERVES • can be entrapped during closure of low transverse incisions, especially if incisions extend beyond the lateral borders of the rectus muscle

• carry sensory information only, and injury leads to loss of sensation within the areas supplied.

EXTERNAL GENERATIVE ORGANS

EXTERNAL GENERATIVE ORGANS PUDENDA or VULVA  includes all structures visible externally from the pubis to the perineum:  Mons pubis  Labia majora and minora  Clitoris  Hymen  Vestibule  Urethral opening  Various glandular and vascular structures

EXTERNAL GENERATIVE ORGANS MONS PUBIS • Also called mons veneris • fat-filled cushion that lies over the symphysis pubis • At puberty, covered by curly hair that forms the escutcheon • In adult women, it is distributed in a triangular area  Base: forms the upper margin of the symphysis pubis

EXTERNAL GENERATIVE ORGANS LABIA MAJORA

• Male homologue: scrotum • It is where the round ligaments terminate (upper boarder) • Outer surface with hair while inner surface without hairs • In children and nulliparous women close apposition • In multiparous women - gapes widely

• continuous directly with the mons pubis • Merge posteriorly to form the posterior commissure.

EXTERNAL GENERATIVE ORGANS

LABIA MINORA

 composed of connective tissue with many vessels and some smooth muscular fibers  moist and reddish, similar in appearance to a mucous membrane  extremely sensitive because its supplied with many nerve endings  2 lamellae superiorly  lower pair: forms the frenulum of the clitoris  upper pair: forms the prepuce  Inferiorly, it forms the fourchette.

EXTERNAL GENERATIVE ORGANS LABIA MAJORA • Lining epithelium  Outer and Lateral portion of inner surface- stratified squamous epithelium  Medial portion- non-keratinized squamous epithelium Hart line- demarcation line between lateral and midline portion

 Contains sebaceous follicles, few sweat glands  Lack hair follicles, eccrine glands and apocrine glands

EXTERNAL GENERATIVE ORGANS CLITORIS • Male homologue: penis • composed of a glans, a corpus, and two crura • rarely exceeds 2 cm in length. • covered by stratified squamous epithelium that is richly supplied with nerve ending • principal female erogenous organ

EXTERNAL GENERATIVE ORGANS VESTIBULE • from embryonic urogenital membrane

• almond-shaped • BOUNDARIES: • Lateral- Hart line • Medial – external surface of hymen • Anteriorly- frenulum • Posteriorly- fourchette

EXTERNAL GENERATIVE ORGANS VESTIBULE • 6 openings: • urethra • vagina • ducts of the Bartholin glands (2) • ducts of the paraurethral glands/skene glands (2)

Vestibular Glands BARTHOLIN’S GLANDS • greater vestibular glands • 0.5 to 1 cm in diameter • lie inferior to the vestibular bulbs and deep to the inferior ends of the bulbocavernosus muscle • ducts are 1.5 to 2 cm long and open distal to the hymenal ring at 5 & 7 o'clock

Vestibular Glands BARTHOLIN’S GLANDS CLINICAL SIGNIFICANCE: • Following trauma or infection, either duct may swell and obstruct to form a cyst, or if infected, an abscess

Vestibular Glands PARAURETHRAL GLANDS • Lies in the inferior aspect of the urethra • Skene glands - largest • Minor vestibular glands - are shallow glands lined by simple mucin-secreting epithelium and open along Hart line.

Vestibular Glands PARAURETHRAL GLANDS CLINICAL SIGNIFICANCE: • Inflammation and duct obstruction of any of the paraurethral glands can lead to a urethral diverticulum formation.

Vestibular Bulbs • Male homologue: corpus spongiosum of the penis • almond-shaped, mainly composed of aggregations of veins • 3 to 4 cm long, 1 to 2 cm wide, and 0.5 to 1 cm thick

• lie beneath the bulbocavernosus muscle on either side of the vestibule.

Bulbocavernosus muscle

Vestibular bulb

Vestibular Bulbs CLINICAL SIGNIFICANCE: • During childbirth, the vestibular bulbs may be injured and may even rupture to create a vulvar hematoma

VAGINAL OPENING AND HYMEN Vaginal opening is rimmed distally by the hymen or its remnants

VAGINAL OPENING AND HYMEN HYMEN • Membrane surrounding the vaginal opening • Composed of elastic and collagenous connective tissue • Covered by stratified squamous epithelium

VAGINAL OPENING AND HYMEN • The aperture of the hymen varies. • Hymen is torn at several sites during first coitus. Identical tears may occur by other penetration. The edges of the torn hymen soon reepithelialize  hymenal caruncle • Imperforate hymen • Rare lesion in which the vaginal orifice is occluded completely, causing retention of menstrual blood

VAGINAL OPENING AND HYMEN VAGINA • Musculo-membranous structure • Extends from the vulva to the uterus • interposed anteriorly and posteriorly between the urinary bladder and the rectum . • Lining epithelium: nonkeratinized stratified squamous epithelium • no glands • abundant vascular supply

VAGINAL OPENING AND HYMEN VAGINA  Embryology  upper portion - müllerian ducts  lower portion - urogenital sinus

VAGINAL OPENING AND HYMEN VAGINA  Anteriorly, the vagina is separated from the bladder and urethra by connective called – vesicovaginal septum

 Posteriorly, there are similar tissues together that form the rectovaginal septum between the lower portion of the vagina and the rectum  The upper fourth of the vaginal is separated from the rectum by the rectouterine pouch or culdesac of Douglas

VAGINAL OPENING AND HYMEN

VAGINA • Length • •

Anterior: 6 – 8cm Posterior: 7 – 10cm

• Subdivided by the cervix into fornices  anterior, posterior, lateral

VAGINAL OPENING AND HYMEN VAGINA •

•

The fornices are clinically important because the internal pelvic organs can be palpated through their thin walls Posterior fornix provides surgical access to the peritoneal cavity

VAGINAL OPENING AND HYMEN VAGINA BLOOD SUPPLY

Upper Third Middle third Lower third

cervicovaginal branches of uterine artery and vaginal artery inferior vesical arteries middle rectal and internal pudendal arteries

LYMPHATIC DRAINAGE

Externa, internal and common iliac nodes Internal iliac nodes Inguinal nodes

PERINEUM  The diamond area between the thighs  Boundaries are same as those of the bony pelvic outlet     

Anterior: Pubic symphysis Posterior: Ischiopubic rami Anterolateral: Ischial tuberosities Posterolateral: Sacrotuberous ligaments Posterior: Coccyx

 Blood supply:  Internal pudendal artery (inferior rectal artery and posterior labial artery)

Anterior triangle, also called the urogenital triangle

Posterior triangle, also called the anal triangle

Ischial Tuberosities – divides the perineum into an anterior and posterior triangle

PERINEUM ANTERIOR TRIANGLE  Also called Urogenital Triangle  Further subdivided into:  Superficial space – closed compartment  Deep space – continuous superiorly with the pelvic cavity

 Boundaries:  Superior: Pubic rami  Lateral: Ischial tuberosities  Posterior: Superficial transverse pernieal muscle

PERINEUM

PERINEUM SUPERFICIAL SPACE OF THE ANTERIOR TRIANGLE Ischiocavernosus

• attached at the ischial tuberosity and crus of clitoris  helps maintain clitoral erection

Bulbocavernosus

• Overly the vestibular bulb and Bartholin glands • Attached at the perineal body and the clitoris • Constrict the vaginal lumen and aid in the release of secretions of the Bartholin’s gland • Contributes to clitoral erection

Superficial transverse perineal muscles

• attach to the ischial tuberosities laterall and the perineal body medially

PERINEUM DEEPSPACE OF THE ANTERIOR TRIANGLE • Deep to the perineal membrane and extends up continuous superiorly with the pelvic cavity • Contains: compressor urethrae, urethrovaginal sphincter muslces, external urethral sphincter, parts of urethra and vagina, branches of internal pudendal artery, dorsal nerve and vein of the clitoris

PERINEUM POSTERIOR TRIANGLE Contains:  Ischiorectal fossa  Anal canal  Anal sphincter complex  Branches of the internal pudendal vessels  Pudendal nerve

POSTERIOR TRIANGLE Ischiorectal fossae • Two fat filled wedge shaped spaces on either side of the anal canal • Provide to surrounding structures, yet allow distension of the rectum during defecation and stretching of the vagina during delivery • Anal canal and sphincter lie in the center of the fossae. • This continuity of the fossae across perineal compartments allows fluid, infection and malignancy to spread.

PERINEUM

PERINEUM PUDENDAL NERVE • Formed by the anterior rami of S2-S4 • Lies posteromedial to the ischial spines

PERINEUM PUDENDAL NERVE •3 terminal branches: • Dorsal nerve of the clitoris – supplies the skin of the clitoris • Perineal nerve – supplies the muscles of the anterior triangle and labial skin • Inferior rectal nerve – supplies the external anal sphincter, mucous membrane of anal canal and the perineal skin

Anus EXTERNAL ANAL SPHINCTERS • A ring of striated muscle attached to the perineal body anteriorly and the coccyx posteriorly • Maintains the constant state of resting contraction • Receives blood supply from the inferior rectal artery • Motor fibers come from the inferior rectal branch of the pudendal nerve

Anus INTERNAL ANAL SPHINCTER • Contributes the bulk of the anal canal resting pressure for fecal continence • Formed by the distal continuation of the inner circular muscle layer of the rectum and colon

ANAL CUSHION • Highly vascularized • Aids in fecal continence • Engorgement due to increased uterine size, excessive straining and hard stools, can increase venous engorgement within these cushions to form hemorrhoids

Perineal body Structures that contribute to the perineal body: • Median raphe of the levator ani • Central tendon of the perineum • Bulbocavernosus m. • Superficial transverse perineal m. • External anal sphincter

INTERNAL GENERATIVE ORGANS

Development of the internal generative organs

Embryological development  Fusion of the two müllerian (paramesonephric) ducts to form a single canal begins at the level of the inguinal crest, that is, the gubernaculum (primordium of the round ligament) – 5th week of development  Upper ends of the müllerian ducts produce the oviducts and the fused parts give rise to the uterus  The vaginal canal is not patent throughout its entire length until the sixth month of fetal life

INTERNAL GENERATIVE ORGANS

Cervix  Internal cervical os  upper boundary; level at which the peritoneum is reflected up onto the bladder

 Portio supravaginalis • is covered by peritoneum on its posterior surface • attached to the cardinal ligaments laterally

 Portio vaginalis

INTERNAL GENERATIVE ORGANS Cervix  External cervical os before childbirth: small, oval opening  External cervical os after childbirth: transverse slit, giving rise to the anterior and posterior cervical lip  Cervical stroma – compose mainly of collagen, elastin and proteoglycan but very little smooth muscle  Ectocervix – nonkeratinized squamous epithelium  Endocervix – mucin-secreting columnar epithelium

INTERNAL GENERATIVE ORGANS

Uterus

 Thick- walled, hollow, muscular organ  Nulliparous: 6- 8cm, fundus and cervix almost equal in length  Multiparous: 9-10cm, cervix is 1/3 of the total length  Entire posterior wall of the uterus is covered by serosa, or peritoneum, the lower portion of which forms the anterior boundary of the recto-uterine culde-sac, or pouch of Douglas.  Blood supply:  uterine artery  ovarian artery

INTERNAL GENERATIVE ORGANS Uterus: Parts • Corpus or body • Cervix • Isthmus – between the internal cervical os and the endometrial cavity; forms the lower uterine segment during pregnancy • Cornua – at the junction of the superior and lateral margins • Fundus – convex upper segment between the points of insertion of the fallopian tubes

INTERNAL GENERATIVE ORGANS Uterus • Layers: • serosa • muscular (myometrium) • mucosa (endometrium)

• The serosal layer is formed by the peritoneum that covers the uterus

INTERNAL GENERATIVE ORGANS Uterus: Myometrium • Bundles of smooth muscle united by connective tissue in which there are many elastic fibers • Relative more muscle in the inner wall than the outer wall, and in the anterior and posterior walls than in the lateral walls • Muscle fibers diminish caudally such that the muscle comprises only 10% of the tissue mass in the cervix • The interlacing myometrial fibers that surround the myometrial vessels are integral to control of bleeding from the placental site during the third stage of labor

INTERNAL GENERATIVE ORGANS Uterus: Endometrium thin, pink, velvet-like membrane perforated by a large number of minute ostia of the uterine glands. Histology  Epithelium - single layer of closely packed high columnar cells than rests on a thin basement membrane  Uterine glands – invaginations of the epithelieum that extend to the myometrium  Interglandular mesenchymal stroma – varies remarkably throughout the ovarian cycle, undergoes decidualization following ovulation

INTERNAL GENERATIVE ORGANS Uterus: Blood supply

INTERNAL GENERATIVE ORGANS Uterus: Endometrium Vascular architecture • Uterine and ovarian arteries  arcuate arteries  radial arteries  spiral/coiled arteries and basal/straight arteries • Spiral arteries – midportion and superficial third of the endometrium, responsive to hormones • Basal arteries – basal layer, not responsive to hormones

INTERNAL GENERATIVE ORGANS ROUND LIGAMENTS  Extend from the lateral portion of the uterus  Arise below and anterior to the origin of the oviducts.  Terminate in the upper portion of the labium majus.  Sampson artery runs within this ligament.  Corresponds embryologically to the gubernaculum testis of men  Clinically significant when doing puerperal tubal sterilization

INTERNAL GENERATIVE ORGANS BROAD LIGAMENTS • Winglike structures from lateral margins to pelvic sidewall • Each consist of an anterior leaf and a posterior leaf • Drapes over structures extending from the cornu • Mesosalpinx, mesoteres, mesovarium, mesometrium • Suspensory ligament or infundibulopelvic ligament – from the fimbriated end of the fallopian tube to the pelvic wall, where ovarian vessels traverse

INTERNAL GENERATIVE ORGANS CARDINAL LIGAMENTS  Transverse cervical or Mackendrodt ligament  Thick base of the broad ligament that is continuous with the connective tissue of the pelvic floor

INTERNAL GENERATIVE ORGANS UTEROSACRAL LIGAMENTS • From its attachment posterolaterally to the supravaginal portion of the cervix and inserts into the fascia over the sacram • Form the lateral boundaries of the pouch of Douglas

INTERNAL GENERATIVE ORGANS LYMPHATICS • Cervix • terminate mainly in the hypogastric nodes, which are situated near the bifurcation of the common iliac vessels.

• Body of the uterus • internal iliac nodes and periaortic lymph nodes

Blood Vessels

INTERNAL GENERATIVE ORGANS FALLOPIAN TUBES  Also called oviducts  Vary in length from 8 to 14 cm.  lumen is lined by mucous membrane. PARTS  interstitial portion  isthmus  ampulla  infundibulum or fimbriated extremity- funnel-shaped opening at the distal

INTERNAL GENERATIVE ORGANS FALLOPIAN TUBES •

•

•

Tubal smooth muscle: inner circular and outer longitudinal, undergo rhythmic contraction or peristalsis toward the uterine cavity Epithelium in close with muscle layer because there is no submucosa Epithelium - columnar cells (some ciliated, others secretory)

INTERNAL GENERATIVE ORGANS Ovaries  the ovaries vary considerably in size.  During childbearing years, they are from 2.5 to 5 cm in length, 1.5 to 3 cm in breadth, and 0.6 to 1.5 cm in thickness.  After menopause, ovarian size diminishes remarkably.

 Rest in a slight depression on the lateral wall of the pelvis, called ovarian fossa of Waldeyer between the divergent external and internal iliac vessels  Attached to the broad ligament by the mesovarium.

INTERNAL GENERATIVE ORGANS Ovaries PARTS: • Cortex- outer layer, contains oocytes and developing follicles • Medulla- central portion, composed of loose connective tissue BLOOD SUPPLY • The ovaries are supplied with both sympathetic nerves from the ovarian plexus and parasympathetic nerves.

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12 13

14,15 – Blood supply to the uterus

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