Pelvis I: Viscera - Weill Cornell Medicine-Qatar - October 2024 - PDF

Pelvis I: Viscera Mange Manyama, M.D., Ph.D. I do not have financial interest in commercial products or services related to the subject of this lecture PollEv.com/ manyama837 Octo...

Pelvis I: Viscera Mange Manyama, M.D., Ph.D. I do not have financial interest in commercial products or services related to the subject of this lecture PollEv.com/ manyama837 October 14, 2024  Suggested readings: Moore: Essential Clinical Anatomy, 7th Ed. 358-384 Bones of the Pelvic girgle Peritoneum and Peritoneal cavity of pelvis Wall & Floor of the pelvic cavity Pelvic Viscera Injury to pelvic floor and Pelvic organs prolapse Hypertrophy of prostate Male sterilization Ectopic tubal pregnancy Culdocentesis  Learning objectives Describe the skeleton of the Pelvis. List the different parts of the Pelvic diaphragm. Describe the Peritoneal reflections of the male and Female Pelvis. Describe the main parts of the Uterus: fundus, body, cervix. Describe the normal position of the Uterus, variations in uterine positions, and support. Describe the anatomy of the Vagina and Ovaries. Describe the Prostate: lobes, and its associated clinical correlations. Describe the anatomy of the Urinary bladder, Seminal vesicles, the Rectum and the Anal canal.  Pelvic Girdle The pelvic girdle is formed by three bones: Right and left hip bones (pelvic bones) - each of which develops from the fusion of 3 bones: ilium, ischium, & pubis. The pecten pubis (pectineal line) is on the upper border of the superior pubic ramus. Provide attachment of the pectineal ligament (an extension of the lacunar ligament).  Pelvic Cavity The Pelvic cavity is the inferoposterior part of the abdominopelvic cavity. It is limited inferiorly by the pelvic diaphragm (made up of muscles and fascia). Below the pelvic diaphragm is the Perineum. The pelvic cavity is divided into greater (false) pelvis and lesser (true) pelvis by the pelvic brim. The pelvic brim is defined by the sacral promontory, arcuate line, iliopubic eminence, pectineal line, pubic crest, and the pubic symphysis. Pelvic walls/Boundaries Muscles of the Pelvic Wall Piriformis (Posterior wall) Obturator internus (Lateral wall) Muscles of the Pelvic Floor (Pelvic Diaphragm) Levator ani Puborectalis Pubococcygeus Iliococcygeus Coccygeus  https://skfb.ly/6QYuR  Pelvic diaphragm The pelvic diaphragm stretches between pubis anteriorly and the coccyx posteriorly and from one lateral pelvic wall to the other. Consist of levator ani and coccygeus muscles Levator ani: is the largest and the most important muscle of the Pelvic floor. Has three parts: – Puborectalis- Forms a U- shaped sling posterior to the anorectal junction. – Pubococcygeus- Arises from the posterior part of the body of the pubis and passes back horizontally. Its tonic contraction bends the anorectum anteriorly. This is important in maintaining fecal continence. – Iliococcygeus: Posterior part of levator ani. The Tendinous arch of the levator ani: Formed from thickening of the obturator internus fascia. The tendinous arch serves as the lateral attachment point for a portion of the levator ani muscles The attachment of the levator ani to the obturator fascia divides the obturator internus into a superior pelvic portion and an inferior perineal portion. Injury to Pelvic Floor The levator ani may be injured during childbirth. The pubococcygeus and puborectalis are the muscles torn most often. Weakening of these muscles decrease support for the vagina, bladder, uterus, or rectum, or alter the position of the neck of the bladder and the urethra leading to urinary stress incontinence and/or prolapse of some of pelvic organs through the vagina e.g. cystocele (urinary bladder), rectocele (Rectum), enterocele (small intestine). Stress urinary incontinence is a condition characterized by involuntary leakage of urine during activities that increase intra-abdominal pressure, such as laughing, sneezing, coughing, or exercising  Also known as pelvic floor muscle training Pelvic floor exercises help prevent prolapse by strengthening the muscles that support the pelvic organs. Imagine you are trying to stop the flow of urine mid-stream or imagine you are trying to stop yourself from passing gas. The muscles you squeeze to do this are your pelvic muscles.  Peritoneal reflections in the pelvis The way the parietal peritoneal reflects onto the different pelvic organs creates some spaces some of which have clinical significance The Rectouterine pouch (Pouch of Douglas) is the inferiormost extent of the peritoneal cavity in the female. It is easy for fluids to collect in this area.  Rectouterine Pouch Culdocentesis is a procedure in which peritoneal fluid is aspirated from the Rectouterine pouch cul-de-sac (pouch of Douglas) through the posterior vaginal fornix. Female Pelvic Viscera  Broad Ligament bbbbbbbb…….b A double layer of peritoneum that extends from the sides of the uterus to lateral walls & floor of pelvis Laterally, the peritoneum of the broad ligament is prolonged superiorly as the suspensory ligament of the ovary. Within this ligament are the ovarian arteries and veins. The three parts of the broad ligament (Mesometrium, Mesosalpinx and Mesovarium) are named based on the structures contained between the double layer.  The ligament of the ovary (attach the ovary to posterior wall of uterus) The round ligament of the uterus (attach anterior wall of uterus to labia majora) enters the inguinal canal through the deep ring of the inguinal canal.  Female Pelvic fascia and support of viscera The Cardinal ligaments (Transverse cervical ligaments or Mackenrodt ligaments) also act to support the pelvic organs of the female pelvis. These ligaments along with the Uterosacral and Pubocervical ligaments, provide support to the uterus, cervix and vagina. In the superiormost portion of the transverse cervical ligament, the uterine artery runs medially toward the cervix while the ureters pass immediately inferior to them (water under the bridge).  Uterus The uterus is a hollow pear-shaped organ with thick musculature It is divided into – Fundus - Lies above the entrance of uterine tubes. – Body - Lies below entrance of uterine tubes, narrows below and becomes cervix. – Cervix - Enters anterior wall of the vagina and is divided into supravaginal and vaginal parts. The cavity of the cervical canal communicates with the vagina through the external os, and with the cavity of the body of the uterus through the internal os.  Position of the Uterus Uterine Displacement & Prolapse The adult uterus is usually anteverted and anteflexed so that its mass lies over the bladder. Anteversion: Uterus is tipped anterosuperiorly relative to the axis of the vaginal canal. Anteflexed: Flexed or bent anteriorly relative to the cervix Retroversion: Fundus and body of uterus are bent backward on the vagina. A retroverted uterus has a higher risk of prolapse through the vagina. Retroflexion: When body of Uterus is bent backward on the cervix.  Uterine Tubes Also known as Fallopian tubes or Oviducts Are about 4 inches (10 cm) long, lies in free edge of Broad ligament, the Mesosalpinx The tubes extend laterally and open into the peritoneal cavity near the ovaries. Divisible into 4 parts –Infundibulum - funnel-shaped distal end of the tube that opens into the peritoneal cavity –Ampulla – widest & longest, thin walled and tortuous. Usual site of fertilization –Isthmus - narrow, straight and thick walled. –Uterine or Intramural - short intramural segment of the tube that passes through the wall of the uterus  Ovaries Almond shaped, suspended from posterior aspect of the broad ligament Release oocytes into peritoneal cavity close to ostia of uterine tubes that are swept up by cilia Connected to the uterus via ovarian ligament. The suspensory ligaments attach each ovary to the pelvic sidewall. This ligament contains the ovarian vessels, lymphatics, and nerves  Vagina Muscular tube extending upwards and backward from the vestibule of the vagina to the cervix. Has anterior and posterior walls which are normally in apposition. The area of the vaginal lumen, which surrounds the cervix is divided into four regions or fornices: Anterior, posterior and right and left lateral. The posterior fornix is the deepest and is closely related to the rectouterine pouch. Male Pelvic Viscera  Prostate Accessory gland of the male reproductive system, surrounding the prostatic urethra. Glandular part comprises ~ 2/3 of the gland, fibromuscular part comprises 1/3 The fibrous capsule of the prostate is dense and neurovascular, incorporating the prostatic plexuses of veins and nerves. The fascia covering the posterior surface of the prostate and separating it from the rectum is the Denonvilliers’ (Rectovesical/Rectoprostatic) fascia.  Lobes of the Prostate Anterior (isthmus): lies anterior to the urethra. Mostly fibromuscular Left and right (lateral) lobes: located on lateral sides of urethra. Forms major part of prostate Median (middle): lies posterior to the urethra. Tends to undergo hormone-induced hypertrophy (Benign Prostatic Hypertrophy, BPH). BPH usually compresses the prostatic urethra, impeding urination. Posterior (inferoposterior): lies posterior to urethra and inferior to ejaculatory duct. Palpable by digital rectal examination. Most prostatic cancer arise in the posterior lobe.  Glandular zones of the prostate Glandular tissue of the prostate arranged in three concentric zones: – Peripheral zone – glands in this zone are prone to carcinoma – Central zone – surrounds the ejaculatory ducts – Transitional zone – prone to benign prostatic hypertrophy The anterior region is usually devoid of glandular components. It is composed of fibromuscular tissues  The prostatic fluid secreted through many prostatic ducts open into the prostatic sinuses on either side of the seminal colliculus on the prostatic urethra Prostatic fluid contains zinc, citric acid and some enzymes, including prostate-specific antigen. Prostatic fluid constitutes ~ 20% of the volume of semen and plays a role in the activation of sperms. Ductus deferens Continuation of the duct of the epididymis. Ascends within the spermatic cord. Ends by joining the duct of the seminal gland to form the ejaculatory duct. Vasectomy - sterilizing method whereby part of the ductus deferens is ligated and/or excised. The subsequent ejaculated fluid contains seminal fluid and prostatic fluid but no sperms. Seminal glands and ejaculatory ducts Lie between the fundus of urinary bladder and the rectum. Secretes an alkaline fluid with fructose The duct of seminal vesicles joins the ductus deferens to form the ejaculatory duct that open into the prostatic urethra Other Pelvic Viscera  Urinary Bladder Separated from the pubic bones by a retropubic space (of Retzius). Has Apex, Body, Fundus, and Neck The detrusor muscle fibers forms the wall of the bladder. Toward the neck of the male bladder, the muscle fibers form the involuntary internal urethral sphincter. The sphincter contracts during ejaculation to prevent retrograde ejaculation of semen into the bladder Trigone is the smooth triangular region of the posterior wall where the muscle fibers are closely adherent to the mucosa  Rectum and Anal canal The rectum ccommences at the level of S3 as a continuation of sigmoid colon. Continues as the anal canal at the level of the tip of the coccyx, where it takes on an acute inferior angle, the anorectal flexure, formed by the puborectalis muscle. The external anal sphincter is the voluntary "gate-keeper" for the anal canal. The internal anal sphincter is smooth muscle and under autonomic nerve control.  Anal canal Anal canal divided into upper and lower portions based on developmental origin The pectinate or dentate line demarcates the junction of the upper and lower anal canal. The superior part of the anal canal (visceral; derived from the embryonic hindgut), and the inferior part (somatic; derived from the embryonic proctodeum). Upper and lower portions have different blood, nerve, and lymphatic supplies. Anal columns are formed by submucosal blood vessels, primarily veins. These veins form the internal venous plexus. A similar plexus lies in the perianal subcutaneous tissues and is termed the external venous plexus. The two plexuses anastomose extensively and are the cause of internal and external hemorrhoids. The nerve supply to the anal canal superior to the pectinate line is visceral innervation from the sympathetic and parasympathetic. It is sensitive only to stretching. The nerve supply of the anal canal inferior to the pectinate line is somatic innervation derived from the inferior rectal nerves. Therefore, this part of the anal canal is sensitive to pain, touch, and temperature.