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