Pelvis lesson 2 Flashcards
Ureters
- Descend into the pelvis near the bifurcation of the common iliac vessels into external and internal iliac vessels
- Course inferior to the uterine artery in the female and inferior to the ductus deferens in the male (“water under the bridge”)
- Due to its close proximity to the uterine artery, the ureter is vulnerable to injury during a hysterectomy, when the uterine artery is ligated prior to removal of the uterus
- Ureters pass obliquely through posterosuperior bladder wall (its oblique passage forms a one-way valve, preventing reflux of urine into the ureters)
What Pelvic Organs Common to Both Sexes?
-Ureters
-Urinary bladder
BOTH are primarily retroperitoneal
What are the characteristics of the Urinary bladder?
- Rugae
- Internal urethral sphincter
- Trigone
Describe the Retropubic space
-Lies posterior to the pubis and anterior to the bladder
Describe the Rugae
- The bladder receives urine from the ureters, stores it, then expels it through the urethra
- Highly distensible smooth muscle walls (detrusor muscle)
- Mucosal folds are prominent when the bladder is empty
- Folds disappear as the bladder distend
- Parasympathetic innervation (pelvic splanchnic nerves) stimulates the contraction of the detrusor muscle
Describe the internal urethral sphincter
- Smooth muscle sphincter at the neck of the bladder that surrounds the opening of the urethra in males
- Sympathetic innervation (e.g., lumbar splanchnic nerves) stimulates its contraction (preventing micturition, preventing sperm from entering the bladder during ejaculation)
- An anatomical internal urethral sphincter is not present in females; however, some consider the neck to function as a physiological sphincter in females, despite the lack of defined, circular muscle fibers
Describe the Trigone
- Triangular portion of the posterior wall defined by the two ureteric orifices superiorly and the urethral orifice inferiorly
- Smooth (no rugae)
- Very sensitive to stretch (visceral sensory innervation stimulates urge to void)
What are some Important relationships of the Urinary bladder?
- In males, the bladder lies superior to the prostate gland
- In babies and children (until puberty), the bladder (even when empty) extends superior to the pubis, where it is susceptible to injury
- In the adult, a distended bladder extends superior to the pubis
- When the bladder is full, a suprapubic incision can be made to access the bladder without traversing the peritoneum and entering the peritoneal cavity
- When bladder is full, it is susceptible to injury (e.g., Motor Vehicle Accident, falls from high places, bicycle accidents, perforations, or heavy objects falling on the lower abdomen can result in rupture).
What are the Female Pelvic Organs
- Uterus
- Endometrium
- Body
- Cervix
- Vagina
- Ovaries
- Uterine (fallopian) tubes
- Broad ligament
Describe the uterus
- Most of the uterus is intraperitoneal (suspended by broad ligament)
- Located between the bladder and rectum
- Myometrium
-Smooth muscle of uterus (distends greatly during pregnancy, superior to the pubic symphysis)
Describe the Endometrium
-Internal lining, glandular mucosa, site of implantation, shed each month
Describe the body
- Superior two thirds of the uterus
- Fundus (rounded superior portion of the body, located superior to the orifices of the uterine tubes)
Describe the Cervix
-Cylindrical inferior one third of the uterus
-Central canal opens superiorly into the body of the uterus at the
internal os
-Central canal opens inferiorly into the vagina at the external os (site of pap smear)
Describe the vagina
- Located between the bladder and rectum
- Continuous with the cervix at the external os
- Courses superiorly and posteriorly
- Anterior and posterior walls contact each other
- The cervix projects into the vagina at its superior end, creating recesses anteriorly, posteriorly, and laterally, called vaginal fornices
- The posterior fornix is the deepest of the recesses and is related to the rectouterine pouch and the rectum posteriorly
- An incision can be made through the posterior fornix to examine the peritoneal cavity endoscopically
Describe the ovaries
- Originate in the posterior abdominal wall, attached to the gubernaculum
- Descend into the pelvis and become attached to the posterior aspect of the broad ligament (ovaries are intraperitoneal)
- The ovarian vessels, nerves, and lymphatics that accompanied the descent of the ovary are enclosed within the suspensory ligament of the ovary
- During ovulation, an oocyte is expelled from the ovary into the peritoneal cavity, towards the abdominal orifices of the uterine tubes
Describe the Uterine (fallopian) tubes
- Intraperitoneal (enclosed in the superior edge of the broad ligament)
- Open into peritoneal cavity at their abdominal orifices which are surrounded by finger-like fimbriae
- Enter the superolateral walls of the uterus at their uterine orifices
- The peritoneal cavity is open in the female and closed in the male
- Pelvic inflammatory disease is much more common in females, as the vagina, uterus and uterine tubes provide a pathway into the peritoneal cavity
- The uterine tubes are the most common site of an ectopic pregnancy
Describe the Broad ligament
-Double layer of peritoneum (mesentery) that extends from the sides of the uterus to the lateral walls and floor of the pelvis; holds the uterus in position and conveys vasculature and nerves to/from the uterus
-The uterine (fallopian) tubes lie in the superior edge of the broad ligament
-The ovaries are attached to the posterolateral border of the broad ligament
-An extension of the broad ligament, the suspensory ligament of the ovary, encloses the ovarian arteries and veins, lymphatic vessels, and nerves
-The broad ligament also encloses the bilateral remnants of the gubernaculum:
• Ovarian ligament (between ovary and uterus)
• Round ligament of the uterus (between uterus and labium majus)
What are the Male Pelvic Organs?
- Testes
- Epididymis
- Ductus (vas) deferens
- Seminal vesicles
- Ejaculatory ducts
- Prostate
Describe the testes
- Originate in the posterior abdominal wall, attached to the gubernaculum
- Descend into inguinal region, pass through deep ring and the inguinal canal, and exit the superficial ring to enter the scrotum
- As the testes descend, some of the parietal peritoneum is drawn into the inguinal canal and scrotum and forms the tunica vaginalis
- A hydrocele is an abnormal accumulation of fluid within the cavity of the tunica vaginalis
- Each testis is covered by a tough fibrous coat, the tunica albuginea
- Internally, the testis contains seminiferous tubules (where the spermatozoa mature)
- Spermatozoa are transported from the seminiferous tubules to the rete testis, then to the efferent ductules, and finally to the epididymis
Describe the Epididymis
- Highly coiled tube located on the posterior surface of the testis
- Connects the testis to the ductus deferens
Describe the Ductus (vas) deferens
- Muscular tube ascends within the spermatic cord, through the superficial ring and inguinal canal, and into the abdomen via the deep inguinal ring (lateral to the inferior epigastric vessels)
- A vasectomy is performed by making an incision in the superior aspect of the scrotum to expose and ligate the ductus deferens
- Courses superior to the ureter (“water under the bridge”)
- When it reaches the posterior aspect of the bladder the ductus deferens enlarges to form an ampulla
- The ampulla of each ductus deferens joins the duct of the seminal vesicle
Describe the seminal vesicles
- Thin walled tubes that are coiled to form a mass that lies between the posterior wall of the bladder and the rectum
- Secrete fluid that mixes with the spermatozoa
- Ducts of the seminal vesicles join the ampullae of the ductus deferens to form the ejaculatory ducts
Describe the Ejaculatory ducts
-Open into the prostatic urethra
What are the different parts of the prostate?
- Base (superior): surrounds the neck of the bladder, internal urethral sphincter
- Apex (inferior)
- Lobes
What are the different portions of the prostate LOBES?
- Anterior lobe (anterior to the prostatic urethra)
- 2 Lateral lobes (on either side of the prostatic urethra)
- Median (middle) lobe (posterior to the prostatic urethra and superior to the ejaculatory ducts)
- Posterior lobe (posterior to the prostatic urethra and inferior to the ejaculatory ducts)
Describe the medial lobe
- Commonly involved in benign hypertrophy of the prostate.
- When the median lobe is enlarged, it stretches the internal urethral sphincter (causing urine leakage), puts pressure on the trigone (creating intense desire to void, especially at night (nocturia)), and can obstruct/narrow the prostatic urethra (making it difficult to void)
Describe the posterior lobe
-The posterior lobe is the most common site of prostatic carcinoma
Describe a Rectal exam in both sexes
- Males: The anterior wall of the rectum is related to the prostate (posterior lobe) and seminal vesicles
- Females: The anterior wall of the rectum is related to the vagina
Describe Difference of Sex Development (DSD)
- DSDs are a group of conditions that affect the process of sex differentiation (reproductive and genito-urinary) during embryological development.
- Related to variations affecting chromosomal, developmental, hormonal, gonadal, or phenotypic sex.
- Approximately 1 in 1500 babies are born with a DSD. Prevalence varies for specific types of DSDs
Describe Individuals who born with Complete Androgen Insensitivity (CAIS)
-46, XY karyotypes but cell receptors do not respond to androgens (directs masculinized sex development). Individuals with a CAIS are phenotypically female with incompletely descended testes, without a uterus, cervix, or fallopian tubes.
Describe Parasympathetic Innervation of the Pelvic Organs
- Preganglionic cell bodies: S2-S4 spinal cord (intermediate gray matter)
- Preganglionic fibers: ventral rootspinal nerveventral ramuspelvic splanchnic nerves
- Postganglionic cell bodies and fibers: walls of organs
-Parasympathetic innervation (pelvic splanchnic nerves) stimulates contraction of the detrusor muscle (promoting micturition)
Describe Sympathetics Innervation of the Pelvic Organs
- Preganglionic cell bodies: lateral horn of the thoracolumbar spinal cord
- Preganglionic fibers travel from ventral rootspinal nerveventral ramuswhite ramus communicanssympathetic trunklumbar and sacral splanchnic nerves
- Postganglionic cell bodies: superior or inferior hypogastric ganglia (primarily the inferior hypogastric)
- Postganglionic fibers: follow arterial branches to target organ
Describe Some exceptions of sympathetic innervation to the pelvic organs
Ovaries/Testes:
- Preganglionic fibers: thoracic splanchnic nerves
- Postganglionic cell bodies: superior mesenteric ganglion
- Postganglionic fibers: follow gonadal vessels to target organ
Describe Visceral sensory of pelvic organs
- The route taken by the sensory fibers differs relative to the pelvic pain line (corresponding to the inferior limit of the peritoneum):
- The pain line in the hindgut is located at the midpoint of the sigmoid colon; so, the visceral sensory fibers from the distal sigmoid colon and rectum follow the parasympathetic fibers back to the CNS.
- Some organs lie superior and inferior to the pelvic pain line (e.g., the bladder, uterus), so both visceral sensory pathways will be utilized (e.g., sensory fibers from the superior aspect of the bladder will follow the sympathetic fibers, while sensory fibers from the inferior aspect of the bladder will follow the parasympathetic fibers back to the CNS)
How does visceral sensory to Structures superior or inferior to the pelvic pain line differ?
- Superior to the pelvic pain line: visceral sensory fibers follow the sympathetic fibers back to the inferior thoracic and superior lumbar spinal cord levels
- Inferior to the pelvic pain line: visceral sensory fibers follow the parasympathetic fibers (i.e., the pelvic splanchnic nerves) back to the S2-S4 spinal cord
The peritoneal cavity extends inferiorly into the ________
pelvis
The peritoneum drapes the pelvic organs; this draping creates spaces where peritoneal fluid can accumulate. What are those spaces called?
- Vesicouterine and Rectouterine pouches in the female
- Rectovesical pouch in the male
