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The external anal sphincter, innervated by the pudendal nerve, provides the brief voluntary contraction necessary to counter the passage of a -?-Peristaltic wave.
The rectal submucosal venous plexus forms anastomotic connections between the middle rectal veins that drain directly into the internal iliac veins and the superior rectal veins which drain int the -?-Hepatic portal system. This is a site for varices (hemorrhoids).
The internal pudendal arteries are the -?-Sole supply of both male and female erectile tissue.
The deep dorsal vein provides venous return from the penis or clitoris by passing through the -?-Urogenital diaphragm and draining into the prostatic or vesicle venous plexus, respectively.
The cremaster muscle of the spermatic cord is innervated by the genital branch of the genitofemoral nerve. This provides the efferent limb for the cremaster reflex (L1-L2), the elevation of the testes within the scrotum when the inner thigh is -?-Scratched.
The cavity of tunica vaginalis is a potential space that represents the detached portion of the peritoneal cavity that surrounds the testis except that the -?-Mesorchium.
Because the superficial perineal space is limited by fascial attachment to the deep transverse perineal muscle, extravasations of blood or urine will not pass into the -?-Anal triangle.
Contents of the perineal spaces are gender specific:
Gender Superficial Perineal Space Deep Perineal Space
-?-Male Testes, crura of penis, bulb of penis, penile urethra, superficial transverse perineal muscles Deep transverse perineal muscles, external urethral sphincter, bulbourethral glands, membranous urethra
-?-Female Crura of the clitoris, vestiular bulbs, superficial transverse perineal muscles, greater vestibular glands Deep transverse perineal muscle, external urethral sphincter, urethra
The male external urethral sphincter is formed by the deep transverse perineal muscle completely surrounding the membranous -?-Urethra. The female external urethral sphincter is formed by muscle fascicles of the deep transverse perineal muscle that arch anterior to the urethra but do not pass posterior because the urethra is embedded in the adventitia of the -?-Anterior vaginal wall. The arrangement in the female -?-Perineum predisposes to urinary stress incontinence.
A pudendal block can be effected by injecting an anesthetic into the vicinity of the pudendal nerve in the pudendal canal close to the -?-Ischial spine.
Pelvic autonomic function:
Function Sympathetic Parasympathetic
L1-L2: Lumbar splanchnic nerves,
hypogastric plexus, pelvic plexus, cavernous plexus
Ejaculation   S3-S5

Pelvic viscera

The female pelvis is less massive, the subpubic angle is greater (almost -?-90°), and the pelvic inlet more ovoid than the male pelvis.
The obstetric conjugate is the least anateroposterior diameter of the pelvic inlet from the sacral promontory to a point a few millimeters below the -?-Superior margin of the pubic symphysis.
The transverse midplane diameter, measured between the ischial spines, is the -?-Smallest dimension of the pelvic outlet.
The levator ani muscle forms most of the pelvic floor and its puborectalis portion (rectal sling) is the principal mechanism for maintenance of -?-Fecal continence when the rectum is full.
Characterization of pelvic structures by location and support:
Characterization Organ
(-?-supported by mesentery)
Sigmoid colon, uterus, uterine tubes, ovaries, testes
-?-Extraperitoneal Rectum, anal canal, urinary bladder, cervix, prostate gland, seminal vesicles
The rectum is usually empty because feces are stored in the sigmoid colon. Movement of feces into the rectal -?-ampulla generates the urge to defecate.
Metastatic carcinoma of the rectum may be widely disseminated within the abdomen, pelvis, and inguinal region. The upper rectum drains along the superior rectal lymphatics. The mid-rectum drains along the middle rectal -?-lymphatics.
The lower rectum drains along the inferior rectal lymphatics, then along both internal and external -?-Pudendal lymphatic channels.
Urinary bladder -?-innervation is by both sympathetic and parasympathetic routes.
Function Pathway
-?-Sensory awareness of bladder fullness Hypogastric nerve (sympathetic pathways) to spinal segments T12-L2
-?-Afferent limb of the detrusor (bladder-emptying) reflex Pelvic plexus and pelvic splanchnic nerves (parasympathetic pathways) to spinal segments S2-S4
-?-Efferent limb of the detrusor reflex Pelvic splanchnic nerves (parasympathetic pathways) from S3-S5
Urinary continence of the partially full to full urinary bladder is a function of the external urethral -?-Sphincter.
A patent urachus (rare) allows -?-Reflux of urine through the umbilicus.
The testes develop as retroperitoneal structures, but become peritoneal (supported by mesorchium) in the scrotum. A -?-Mesorchium may predispose to testicular torsion with high potential for testicular ischemia and necrosis.
The testicular pampiniform plexus functions as a counter-current heat exchanger tht maintains testicular temperature a few degrees below -?-Core body temperature.
Compression of the left testicular vein by a full sigmoid colon produces varices of the pampiniform plexus on the -?-left side; fertility may -?-diminish.
In the -?-Male, palpable per rectum are posterior and lateral lobes of the prostate gland, seminal vesicles if enlarged, and bladder when filling.
Each uterine artery crosses immediately superior to ta rreter in the transverse cervical ligament-an important -?-surgical consideration.
Normal uterine position is anteflexed (uterus bent forward on itself at the level of the internal os) and anteverted (angled approximately 90° anterior to the -?-Vagina), lying on the urinary bladder.
In the -?-Female, palpable per vagina are the cervix and ostium of the uterus, the vagina, the body of the uterus if retroverted, the rectouterine fossa, and variably the ovary and uterine tubes.
The lymphatic drainage from the vagina is by three routes: the external and internal -?-Iliac nodes from the upper third of the vagina; the internal iliac nodes from the middle third of the vagina; and the internal iliac nodes as ell as the superficial inguinal nodes from the lowest third.
Pain referral from pelvic viscera:
Organ Referral Area Pathway
Testes and ovaries -?-T10-T12: Umbilical and pubic regions Gonadal nerves to aortic plexus then to lesser and least splanchnic nerves
Middle urters, urinary bladder, uterine body, uterine tubes -?-L1-L2: Pubic and inguinal regions, anterior scrotum or labia, anterior thigh Hypogastric plexus to aortic plexus then to lumbar splanchnic nerves
Rectum, superior anal canal, pelvic ureters, cervix, epididymis, vas deferens, seminal vesicles, prostate gland -?-S3-S5: Perineum and posterior thigh Pelvic plexus to pelvic splanchnic nerves