Lecture 2.6 - Pelvis and Perinum Flashcards
What consists in the Pelvic region?
- area of transition between trunk and lower limbs
- enclosed by bones, ligaments, and muscles
What is the difference between Pelvic inlet and Pelvic outlet?
Inlet
- marked by arcuate line of ilium and pectineal line of pubis
- superior and open to abdominal cavity
Oulet
- marked by the ischial tuberosities, pubic symphysisis and arch, and coccyx
- inferior and closed to pelvic diaphragm
– levator ani m. and coccygeus m.
Sex differences in pelves?
Male pelvis: - heart shaped inlet - smaller outlet Female pelvis: - oval shaped inlet - larger pelvis outlet, everted ischial spines - shallower greater and lesser pelves - rounded and wider subpubic angle
What is the Pelvic cavity? Divisions?
- funnel shaped space bount by the bones of the pelvis
- greater pelvis: between the ala of ilium and pelvic inlet
- lesser pelvis: between pelvic inlet/outlet
- continuous with abdominal cavity
- contains urinary bladder, terminal parts of ureters, pelvic genital organs, and recutm
What is the Perineum?
- triangular area of trunk between thighs and buttocks extending from the pubis to the coccyx
- seen best in lithotomy position - diamond shaped
- separated from pelvic cavity by the pelvic diaphragm
Perineum contents?
Males: - penis, scrotum, anus Females: - vulva (clitoris, vagina, anus Consists of 2 parts: urgenital triangle/region and anal triangle/region
Obturator Internus (OINA)
O: ilium, superior pubic ramus, ischium (anterolateral wall of lesser pelvis)
I: greater trochanter of femur
N: nerve of obturator internus
A: not relevant for pelvic diaphragm
Piriformis (OINA)
O: 2-4th sacral segments I: greater trochanter of femur N: S1-S2 A: not relevant for pelvic diaphragm runs through the greater sciatic foramen, along with lots of nerves and arteries going to the gluteal region
What is the Pelvic diaphragm and what does it do?
- = levator ani m. + coccygeus m.
- forms floor of pelvis, supporting abdominopelvic organs
- aids in urinary and fecal continence
- supports the abdominopelvic viscera during coughing, sneezing, etc.
- raises the pelvic floor during urination, vomiting, coughing, and weight lifting, increasing intra-abdominal pressure
- during parturition, supports the fetal head while the cervix dilates for delivering the baby
What is Tendinous arch of levator ani formed form?
- formed by the thickened fascia of obturator internus m.
- origin of levator ani m.
Iliococcygeus (OINA)
O: tendinous arch of obturator fascia
I: perineal body, coccyx
N: S4
A: supports pelvic viscera
Puberorectalis (OINA)
O: inferior ramus of pubis
I: rectum, prostate in males, vaginal in females
N: S4, S5
A: supports pelvic viscera
Pubococcygeneus (OINA)
O: inferior ramus of pubis, tendinous arch of obturator internus
I: coccyx
N: S4/S5
A: supports pelvic viscera
Coccygeus (OINA)
O: ischial spine
I: inferior end of sacrum, coccyx
N: S4/S5
A: supports pelvic viscera and flexes coccyx
What are the qalls of pelvic cavity posteriorly? Anteriorly? Laterally? Inferiorly? Superiorly?
Posterior: sacrum, piriform m. Anterior: pubic rami/symphysis Lateral: obturator internus Inferior: levator ani muscles, coccygeus Superior: open to abdominal cavity
What are the Arteries in Pelvis?
- aorta
- common iliac a.
- external iliac (becomes femoral a. to lower limb), and internal iliac a.
- – iliolumbar, lateral sacral, superior/inferior gluteal, internal pudendal, middle rectal, umbilical, superior/inferior vesical, obturator a.
Blood supply of pelvis mostly from internal iliac artery branches to…
To pelvic viscera: 1. umbilical a. to superior vesical a. 2. inferior vesical a (female)/uterine a. (male) 3. middle rectal To walls of pelvis: 4. lateral sacral a. 5. iliolumbar a. Exits to perimeum: 6. internal pudendal a. to inferior rectal a. Exits to lower limb: 7. obturator a. 8. superior gluteal a. 9. interior gluteal a.
Where do gonads and rectum receive their blood?
- gonads (testis and ovary) receive their blood from the abdominal aorta
- rectum receives additional blood from the inferior mesenteric artery (superior rectal artery)
What are the components of the Urinary system? What is the difference between children and adults?
- ureters: drain urine from kidneys to urinary bladder
- urinary bladder: temporarily stores urine
- urethra: conducts urine from urinary bladder to exterior
- in adults, the urinary bladder is the retropubic space within the lesser pelvis.
- in children, the bladder is in the abdomen; enters the greater pelvis at 6 years of age and the less pelvis at 16
What is the wall of the bladder made of? What sphincters are within the wall?
- wall of bladder made of detrusor muscle
- internal (involuntary) and external (voluntary) urethral sphincters help maintain urinary continence
- internal sphincter also prevents semen from entering bladder during ejaculation
Where are sympathetic and parasympathetic innervation located in urinary bladder and what do they do?
- sympathetic (T11-L2) = maintain continence by contraction of internal sphincter
- parasympathetic (S2-S4) = allows urination by relaxing internal sphincter and contracting detrusor muscle
What are the 4 parts of the male urethra?
male urethra is long and described in parts:
- intramural part
- prostatic urethra
- intermediate part
- spongy urethra
What is the function of ductus deferens? Epididymis? Seminiferous tubules?
Ductus = transmits sperm to ejaculatory duct during emission Epididymis = stores sperm prior to ejaculation Seminiferous = produces sperm
What is the pathway of the male pelvic viscera?
- the ductus deferens takes pathway superior, then posterior to the bladder to transmit sperm from epididymis of the testis to the ampulla of the ductus deferens, where it joins the duct of the seminal gland to form the ejaculatory duct
- ejaculatory duct then opens into the prostatic urethra
Where is semen made? Function of ejaculatory duct and bulbourethral glands wtih sperm?
- 65-75% of semen is made of the fluid secreted by the seminal glands
- 25-30% of semen is made of secretions from prostate gland
- ejaculatory duct brings seminal fluid and sperm through the prostate into the prostatic urethra
- bulbourethral glands secrete a lubricating fluid during sexual arousal (<1% of semen)
- sperm is only 2-5% of semn
What are the structures of the penis?
- erectile tissue = spongy tissue that fills with blood to become swollen
- spongy urethra runs through the corpus spongiosum
- at the base of the penis, the corpus cavernosum is called the crus of the penis and the corpus spongiosum is called the bulb of the penis
- at the tip of the penis, the corpus spongiosum expands into the glans of penis
At the base of the penis, the erectile tissue is covered by what to help maintain erection?
- ischiocavernosus m. covers the crus of the penis
- bulbospongiousus m. covers the bulb of the penis
- both are innervated by the pudendal nerve.
What are the structures of the female pelvic viscera?
- female urethra is short
- vaginal canal lies between urethra and bladder (anteriorly) and anal canal and rectum (posteriorly)
- vaginal canal ends in an expanded fornix that surrounds the cervix of the uterus
What is the broad ligament?
- the uterus, uterine tubes, and ovaries are suspended in a double layer of peritoneum called the broad ligament, which secures everything to the lateral pelvic wall
What is prolapsed uterus?
- results when the uterus descends abnormally into the vagina
What are the muscles in the female genitalia?
- ischiocavernosus m covers the crus of clitoris
- bulbospongiousus m. covers the bulbs of vestibule (the vestibule is the region between labia minora)
What are the parasympathetic innervation for sexual function, defecation, and urination?
- located S2-S4
Sexual: - erection = relaxation of the smooth muscles in the walls of arteries, allowing blood to fill erectile tissue
Defecation/urination: - relaxation of smooth muscle internal sphincters of bladder and rectum, contraction of the smooth muscles in the walls of these organs
What are the sympathetic innervation for sexual function, defecation, and urination?
- located T12-L2
Sexual: - ejaculation in males: contraction of the smooth muscles in the walls of ductus deferens, the seminal vesicles, prostate and urethra
- orgasm in females: rhythmic contractions of the smooth muscles in the walls of the vagina
Defecation/urination: - contraction of smooth muscle internal sphincters to maintain continence
What are the voluntary (somatic) control innervation for sexual function, defecation, and urination?
- located S2-S4, pudendal n.
Sexual: - contract bulbospongiousus and ischiocavernosus to assist in erection
Defecation/urination: - contraction of striated muscle external sphincters to maintain continence
What are the somatic innervation for sexual function?
- located S2-S4, pudendal n.
- general sensation to external genitalia for arousal
What are the visceral sensory innervation for defecation and urination?
- stretch for defecation and urination reflexes and pain/cramping
- above pelvic pain line, returns via sympathetic nervs to T12-L2
- below pelvic pain line, returns via parasympathetic nerves to S2-S4
What control functions of ovaries, uterus, and testes?
- primary controlled by hormones
- ovulation, spermatogenesis, uterine contractions during menstruation and childbirth