FEMALE GENITALIA/PELVIC/PERINEAL REGIONS



FEMALE GENITALIA/PELVIC/PERINEAL REGIONS

Gwen Obedencio

Before I get into the pelvic area, let me start with the kidneys and related structures.

Kidney

➢ Vascularization: left and right renal arteries and veins (branching of these vessels is sometimes arbitrary…as a result, the kidneys may get blood supply from two renal arteries). The left renal vein passes anterior to the aorta.

➢ Innervation: renal plexus supplied by fibers from the lesser and lowest splanchnic nerves; consist of both sympathetic and parasympathetic fibers.

➢ Lymphatics: lymph vessels follow the renal vein and drain into the lumbar lymph nodes.

➢ It is retroperitoneal.

➢ Location: contacts ribs 11 and 12; lie at the level of T12 to L3 vertebrae

➢ Covering: surrounded by a fibrous capsule and fat and fascia; from outside to inside, the layers are: parietal peritoneum, pararenal fat, renal fascia, perirenal fat.

➢ Renal Hilum: contains renal veins and arteries and the renal pelvis which narrows to become the ureter.

➢ Internal Parts: (see atlas) medulla, cortex, renal columns, renal pyramids, renal papilla, minor calyx, major calyx, renal pelvis.

Ureters

➢ Vascularization: arterial supply – from three main sources: renal artery, superior vesical artery, and common iliac artery or aorta; however, some other sources may include the testicular or ovarian artery, internal iliac, inferior vesical and the uterine artery. Venous drainage – into the testicular or ovarian veins.

➢ Innervation: same as the kidney.

➢ Lymphatics: drains into the lumbar, common, external, and internal iliac lymph nodes.

➢ It is retroperitoneal and it adheres closely to the parietal peritoneum.

➢ Function: carries urine from the kidney to the bladder.

➢ Location: lie anterior to the psoas major muscle; right ureter lies closely to the inferior vena cava, lumbar lymph nodes, and the sympathetic trunk.

PELVIC REGION

Bladder

➢ Vascularization: arterial supply: the superior vesical arteries, branches of the umbilical arteries supply the anterosuperior parts of the bladder; meanwhile, in the male, the inferior vesical arteries supply the fundus of the bladder while the vaginal arteries supply the posteroinferior parts of the bladder in the female. The obturator and the inferior gluteal arteries also supply parts of the bladder. Venous drainage: in the male, it includes the vesical venous plexus, the prostatic plexus, and the vertebral venous plexuses. In the female, it’s just the vesical venous plexus.

➢ Innervation: Parasympathetic fibers: from the pelvis splanchnic nerves (S2-S4) – they’re motor to the detrusor muscle and inhibitory to the internal sphincter. Therefore, when the fibers are stimulated, the internal sphincter relaxes, and urine flows out. Sympathetic fibers: derived from T11-L2 and they are inhibitory to the bladder. Both the parasympathetic and sympathetic fibers form the vesical nerve plexus.

➢ Lymphatics: the superior part drains into the external iliac lymph nodes, and the inferior part drain into the internal iliac lymph nodes.

➢ Function: stores urine; characterized by its distensibility.

➢ Location: lies posterior and superior of the pubic bones and is separated from the pubic bones by the retropubic space.

➢ Covering: its superior part is covered by peritoneum, which is continuous to the anterior wall of the uterus – this creates a pouch called vesicouterine pouch in the female. In the male, the peritoneum is reflected from the bladder to the superior part of the vas deferens.

➢ Internal Parts: (see atlas) ureters, trigone area, orifice of ureter, internal urethral orifice, neck, apex, base (fundus), superior side, and 2 inferolateral sides.

Urethra

➢ Vascularization: internal pudendal and vaginal arteries and veins.

➢ Innervation: nerves arising from the pudendal nerve; afferent fibers run into the pelvic splanchnic nerves.

➢ Lymphatics: most drain into the sacral and internal iliac lymph nodes; some to the inguinal lymph nodes.

➢ Function: short muscular tube (in females) that passes urine from the bladder to the outside world. The external urethral orifice is located in the vestibule of the vagina. The inferior part is surrounded by the sphincter urethrae muscle.

➢ Location: from the bladder to an opening anterior to the vagina.

INTERNAL GENITALIA

Vagina

➢ Vascularization: arterial supply – mostly from the two vaginal arteries; the internal pudendal and the middle rectal arteries can also supply the vagina. Venous drainage – vaginal venous plexuses which drain into the internal iliac veins.

➢ Innervation: vaginal nerves derived from the uterovaginal plexus, inferior hypogastric plexus, and the pelvic splanchnic nerves.

➢ Lymphatics: drain into the external and internal iliac lymph nodes, superficial inguinal lymph nodes, and some drain into the sacral and common iliac lymph nodes.

➢ Function: female organ of copulation; a musculomembranous tube or sheath that serves as the female genital tract and birth canal.

➢ Location: posterior to the bladder and anterior to the rectum; pierces the urogenital diaphragm; its anterior wall is in contact with the cervix of the uterus – the uterus lies at a right angle to the axis of the vagina; the vaginal recess around the cervix is called the fornix and is divided into the anterior, posterior, and lateral parts.

➢ Related Structures: sphincters - 1. Pubovaginalis muscle 2. Urogenital diaphragm 3. Bulbospongiosus muscle.

Uterus

➢ Vascularization: uterine arteries; some parts are supplied by the ovarian arteries; uterine venous plexus drains the venous system

➢ Innervation: nerves arising from the inferior hypogastric plexus (T10-L1) are for sympathetic innervation; parasympathetic fibers are from the pelvic splanchnic nerves (S2-S4).

➢ Lymphatics: drain into the aortic lymph nodes, internal and external iliac lymph nodes, superficial inguinal lymph nodes, and sacral lymph nodes.

➢ Internal Structures: superior 2/3 is the body, the inferior 1/3 is the cervix; a narrowing between the body and the cervix is called, the isthmus; the superior part of the body is called the fundus. The wall is composed of 3 muscles: (from outermost to innermost) perimetrium, myometrium, endometrium.

➢ Covering: like the vesicouterine pouch formed by the peritoneum between the uterus and the bladder anteriorly, a rectouterine pouch is also formed posteriorly by the peritoneum between the rectum and the uterus.

Uterine Tubes

➢ Vascularization: uterine and ovarian arteries and veins.

➢ Innervation: uterine and ovarian plexuses.

➢ Lymphatics: aortic lymph nodes.

➢ Structural Parts: divided into 4 parts (from the uterus to the end) 1. Uterine part 2. Isthmus 3. Ampulla – usually where fertilization occurs 4. Infundibulum. At the end of the infundibulum are the fimbrae, which are finger-like processes that spread over the ovary for the collection of eggs.

Ovaries

➢ Vascularization: ovarian arteries and veins

➢ Innervation: ovarian plexus

➢ Lymphatics: aortic lymph nodes

➢ Function: produces eggs

Ligaments

➢ Suspensory Ligament: connect the superior end of the ovary to the lateral wall of the pelvis; contains the ovarian vessels and nerves; passes through the mesovarium of the broad ligament and the hilum of the pelvis.

➢ Ovarian Ligament: attaches the inferior end of the ovary to the lateral wall of the uterus; passes through the mesovarium of the broad ligament.

➢ Round Ligament: (of the uterus) passes through the inguinal canal and attaches to the internal surface of the labium majus.

➢ Broad Ligament: ligament around the uterus and related structures; it is a fold of peritoneum with mesothelium on its anterior and posterior surfaces; holds the uterus in normal position; it is a double-layered sheet that extends from the sides of the uterus to the lateral walls and floor of the pelvis; the ovarian ligament lies posterosuperiorly and the round ligament lies anteroinferiorly within the broad ligament; has 3 parts:

□ Mesovarium: attaches the ovaries to the broad ligament anteriorly.

□ Mesosalphinx: part of the broad ligament between the ovarian ligament, the ovary and the uterine tube.

□ Mesometrium: the rest of the broad ligament below the ovarian ligament.

PERINEUM REGION

➢ Vascularization: branches of the external and internal pudendal vessels which include the perineal vessels (terminate as labial arteries), artery of the bulb (supplies the bulb of the vestibule and greater vestibular gland in the female), and the deep and dorsal arteries of the penis/clitoris (deep travels within the corpora cavernosa and the dorsal is more superficial).

➢ Innervation: pudendal nerve branches – perineal nerve (motor to the muscles and sensory to the labia majora) and the dorsal nerve to the penis/clitoris; also branches of the ilioinguinal nerve, the genital branch of the genitofemoral nerve, and branches of the femoral cutaneous nerve of the thigh.

➢ Lymphatics: superficial and deep inguinal lymph nodes

➢ Structures:

-Deep Perineal Pouch

▪ Muscles: deep transverse perineous and the sphinchter urethra

▪ Female deep space: vagina and urethra

-Superficial Perineal Pouch

▪ Clitoris: erectile organ of the female; it is made of the crura of the clitoris which originate from the internal surface of the ramus of the ishium – the two crura meet midline to form the clitoris; the crura is surrounded by the ishiocavernosus muscle at the origin; the clitoris has a root, a body, two corpora cavernosa which are tissue continuous from the ishiocavernosus muscle, and a glans. Suspended by a suspensory ligament.

▪ Bulb of the Vestibule: two erectile tissues lateral to the vaginal orifice; covered by the bulbospongiosus muscle; separated by the clitoris and the vestibule of the vagina unlike the bulb of the penis, its counterpart in the male.

▪ Greater Vestibular Glands: located on each side of the vestibule of the vagina; secrete lubricating mucous during sexual arousal; lie posterior to the bulb of the vestibule (aka Bartholin’s glands)

▪ External Urethral Orifice: located posterior to the clitoris and immediately anterior to the vaginal orifice.

▪ Vaginal Orifice: larger opening anterior to the rectum and posterior to the smaller external urethral orifice; surrounded by a thin mucous membrane called the hymen.

▪ Vestibule of the Vagina: space between the labia minora; the vagina, urethra, and the ducts of the greater vestibular glands open to the vestibule.

▪ Labia minora: thin, fat-free, hairless folds of skin between the labia majora; they meet anterior to the clitoris to form the prepuce and posteriorly to form the frenulum; enclose the vestibule of the vagina.

▪ Labia majora: folds of skin filled with subcutaneous fat lateral to the labia minora; serves to protect structures within the labia minora and the vestibule of the vagina; the two folds meet anteriorly to form the anterior labial commisure.

▪ Mons Pubis: rounded fatty elevation anterior to the pubis symphysis.

▪ Perineal Body: tendinous center of the perineum; wedge-shaped fibrous tissue; landmark of the perineum because several muscles attach there (transverse perineal, bulbospongiosus, levator ani, etc)

▪ Muscles: superficial transverse perineus muscle – two small horizontal muscles that attach to the perineal body and the ishial tuberosity

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