Lecture 24: Male Pelvic Cavity Flashcards
What is the pelvic cavity?
funnel-shaped space surrounded by pelvic bones and it contains organs, such as the urinary bladder, rectum, and pelvic genitals
What bones form the borders of the pelvic cavity?
Hip bones, sacrum and coccyx
What 3 bones fuse together at puberty to form each hip bone?
What is the function of the bony pelvis?
- Supports and protects the pelvic viscera
- transmits upper body weight to lower extremities
- provides a stable base for lower limb function
- forms birth canal
What are the 2 joints of the Pelvis, and the movement that occurs?
- Pubic symphysis - a relatively immobile fibrocartilaginous joint
- Sacroiliac joints - synovial joints formed between the right and left ilia and sacrum. Minimal gliding and rotational movements occur at these joints
What are the 2 main pelvic ligaments?
- Sacrospinous ligament
- Sacrotuberous ligament
What foramen are created by sacrotuberous and sacrospinous ligaments?
- Greater Sciatic Foramen
- Lesser Sciatic Foramen
What is the obturator membrane?
an irregular and thin fibrous sheet that partially closes the obturator foramen
What is the superior pelvic aperture (pelvic inlet) the boundary for?
- Delineated by pelvic brim
- Boundry between the pelvis major and pelvis minor
Where is the pelvis major and pelvis minor, and what organs do they contain?
Pelvis Major (false pelvis): Superior to pelvic brim; contains abdominal viscera.
Pelvis Minor (true pelvis): Inferior to pelvic brim; contains pelvic viscera
What is the inferior pelvic aperture (pelvic outlet, birth canal) delineated by?
- Delineated by ischial tuberosities, ischial spines, ischipubic rami, and coccyx
- Diamond shaped area corresponding with perineum
What are the 2 fascia’s of the pelvis?
- Parietal pelvic fascia
- Pelvic periotoneum
What is the parietal pelvic fascia?
investing fascias of the pelvic muscles line the pelvic cavity and are continuous with abdominal muscular fascia
What is the pelvic peritoneum: differences between men and women
peritoneum that invests abdominal organs extends into the true pelvis and partially invests the pelvic organs forming folds and spaces between them
a. Males and females – spaces on either side of the rectum (pararectal fossa) and urinary bladder (paravesical fossa)
b. Males only – pouch between the rectum and seminal vesicles/urinary bladder (rectovesical) and a fold between the sacrum and prostate/bladder (sacrogenital)
Describe the difference between hip fractures and pelvic fractures
Hip fractures - fractures of the femoral head, neck or trochanters
Pelvic fractures - Fractures of the hipbone (damage to pelvic viscera must be considered in cases of pelvic fractures
What are the two major muscles of the pelvic lateral wall? What nerves innervate them?
Two lateral rotators of the thigh originate from the bony pelvis and insert on the greater trochanter of the femur. Both are innervated by the muscular branches of the sacral plexus
- Obturator internus
- Piriformis
Where is the obturator internus, and where does its tendon exit?
a. Medial surface covered by obturator fascia
b. Tendon exits the pelvis via the lesser sciatic foramen to insert onto femur
What nerve plexus is assoc. w/ Piriformis? Where do its tendons exit the pelvis?
a. Site of the sacral plexus
b. Tendon exits the pelvis via the greater sciatic foramen to insert onto femur
What is the pelvic floor composed of and its 2 muscles?
- Formed by the pelvic diaphragm: a bowl-shaped group of skeletal muscles that partially closes off the pelvic outlet
- supports the abdominopelvic viscera, especially when intra-abdominal pressure is raised (e.g. during coughing or straining)
- Coccygeus
- Levator ani
What is the function of the coccygeus? What does it do in other mammals?
pulls coccyx anteriorly and supports pelvic viscera; wags tail in other mammals
What is the function of the Levator ani? What’s it important for?
elevates the pelvic floor to resist and/or raise intra-abdominal pressure (important for forced expiration, coughing, or vomiting)
What are the 3 main foramen between pelvis, lower limb and perineum?
- Obturator Canal / foramen
- Greater Sciatic foramen
- Lesser Sciatic Foramen
What is the obturator canal and what structures pass through it?
- Connects the abdominopelvic region with medial compartment of thigh
- Transmits obturator n./a./v.
What does the greater sciatic foramen connect, and what structures pass through it?
- Connects pelvic cavity with gluteal region
- Piriformis n. exits pelvis here
- Superior gluteal n./a./v. pass superior to piriformis m.
- inferior gluteal n./a./v. and pudendal nerve pass inferior to the piriformis m
What does lesser sciatic foramen connect, and what passes through it?
- Connects gluteal region with perineum
- Tendon of obturator internus m. exits pelvis here
Identify indicated structures
What structure is this?
Inferior pelvic aperature
What is the sacral plexus? What does it supply? What forms its roots?
Supplies sensory and motor innervation to the perineum, gluteal region, and lower
extremity. Most of these nerves exit the pelvis via the greater sciatic foramen.
2. Roots (ventral rami of L4-S4)
a. L4 and L5 form lumbosacral trunk
What are the 4 branches of the sacral plexus?
a. Sciatic nerve: motor and sensory to lower extremity that has two components
(tibial and common fibular).
b. Pudendal nerve: motor and sensory to perineum, genitals
c. Superior gluteal nerve: motor to gluteus minimus and medius muscles
d. Inferior gluteal nerve: motor to gluteus maximus
What artery provides a majority of bloodflow to the pelvis?
The internal iliac artery
What 3 arteries branch of the posterior division of the internal iliac artery?
- Iliolumbar
- Lateral Sacral
- Superior gluteal -
What structures does the superior gluteal artery pass through?
passes posteriorly between the lumbosacral trunk and S1ventral ramus, superior to piriformis m
What are the 3 main arteries branching from anterior division of internal iliac?
- Obturator a. supplies medial compartment of thigh
- Internal pudendal a. travels with pudendal n. to supply perineum
- Inferior gluteal a. exists pelvis between S2 and S3, emerging inferior to piriformis
What cavity is this?
Peritoneal cavity
Identify the male pelvic fascias.
What are the internal genital organs of the male reproductive system?
A. Internal genital organs
1. Testis (pl. testes) and epididymis (pl. epididymides)
2. Ductus deferens (pl. ductus deferentes)
3. Prostate gland, seminal vesicles, and ejaculatory ducts
What is the external genital organ?
Penis
What are the testes, and what occurs there?
- Male gonads
- Paired structure, suspended in the scrotum by the spermatic cords
- Source of male hormones, mainly testosterone and site of spermatogenesis
Where is sperm produced?
Sperm (spermatozoa) are formed in the seminiferous tubules
Densely packed—average testis contains 400-600 seminiferous tubules
What provides and drains blood from the testicles?
Testicular arteries and veins
Where do the left and right testicular veins drain?
Right testicular vein drains into Inferior Vena Cava, left drains into left renal vein.
What is the epididymis, and what are its 3 sections?
- Elongated structure on the posterior surface of the testis (uncoiled, 6m long!)
a. Head (most superior)
b. Body (convoluted duct)
c. Tail (continuous with the ductus deferens) - Stores sperm until mature
What is the ductus (vas) deferens?
Muscular tube that transports sperm from testis to the urethra during ejaculation
What is a vasectomy / deferentectomy?
Cutting and tying of the ductus (vas) deferens to prevent the passage of sperm.
What are the main structures of the spermatic cord?
- Ductus deferens
- Testicular Artery
- Pampiniform plexus of veins
What are the ejaculatory ducts?
- A slender tube that arises by the union of the duct of a seminal gland with the ductus deferens
- Course through the tissue of the prostate gland to open into the prostatic urethra
Do the ureters pass superior or inferior to the ductus deferens?
Inferior (water under the bridge)
What are the seminal vesicles? What do they secrete?
- Densely coiled blind tubes (~15cm long) located posterior to the base of the bladder
- Secrete a viscous fluid, rich in fructose (to nourish sperm)
and prostaglandin fluid (to help stimulate uterine contractions) which form about 70% of semen
What are the three glands that contribute secretory contents to semen?
What is the prostrate (size / shape)? What does it secrete?
- Largest accessory organ of the male reproductive tract (size of chestnut/walnut)
- A cone-shaped gland with a broad base that contacts with bladder and surrounds the prostatic urethra.
- Contributes thin, milky fluid rich in substances than enhance sperm motility and enzymes that clot and liquefy semen (contributes 20-30% of total seminal volume)
What blood vessels supply the prostate and seminal vesicles?
- Branches of the internal iliac artery
- Venous blood drains to the prostatic and then to the internal vertebral venous plexus
What provides innervation to the prostrate?
Autonomic innervation is via the prostatic plexus (a subdivision of the inferior hypogastric [pelvic] plexus)
What 2 things can be detected with a digital rectal exam?
- Benign Prostatic Hyperplasia (BPH)
- Prostate Cancer.
What is benign prostatic hyperplasia? What are some symptoms?
Prostatic enlargement common in older individuals, affecting ~90% of men by age 80.
Symptoms include urinary retention due to blockage of the urethra.
How does prostate cancer present upon a digital rectal exam?
Prostate cancer usually presents as a hard, irregular mass during a digital rectal exam
What is the penis?
The male organ of copulation, erect in anatomical position
What are the two cylindrical erectile bodies in the shaft of the penis?
Bound together by a dense connective tissue sheath:
1. Corpus cavernosa (right and left)
2. Corpus spongiosum - unpaired midline structure
a. Terminates distally as the glans (head) of penis
b. Traversed by the penile (spongy) urethra which opens onto the glans at the external urethral meatus
What is the prepuce?
Foreskin
1. Loose hood of skin and fascia that extends distally around glans
2. Male circumcision is the surgical removal of the prepuce
Identify indicated structures
