Pelvis and Perineum Flashcards
Bony Pelvis
A basin-shaped bony ring that attaches the lower limbs to the spine and supports the visceral organs of the pelvis
The pelvis is formed by how many bones?
4 bones:
2 Hip bones (os coxae)- Fusion of the ilium, ischium, and pubis during puberty
Sacrum
Coccyx
Divisions of the Bony Pelvis
Greater (false) pelvis and a lesser (true pelvis)
What separates the Greater and Lesser Pelvis?
The pelvic brim
Greater Pelvis
Houses certain abdominal viscera
Lesser Pelvis
Accommodates pelvic viscera- bladder and reproductive organs
Differences between Male and Female Pelvis
Female Sacrum: Wider; shorter sacral curvature is accentuated
Female Coccyx: More movable; straighter
Female Greater Sciatic Notch: Wide and shallow
Female Pelvic Inlet (brim): Wider; oval from side to side
Female Pelvic Outlet: Wider; ischial tuberosities shorter, farther apart, and everted
Male Sacrum: Narrow; longer; sacral promontory more ventral
Male Coccyx: Less movable; curves ventrally
Male Greater Sciatic Notch: Narrow and deep
Male Pelvic Inlet (brim): Narrow; heart-shaped
Male Outlet: Narrower; ischial tuberosities are longer, sharper, and point more medially
Pelvic Ligaments
- Weight of the trunk tends to rotate the sacrum anteriorly
- Pelvic ligaments are arranged to resist this force
What hormone releases during pregnancy?
Relaxin
Pelvic Diaphragm
- Extends from the pubic symphysis to the coccyx
- Separates pelvic viscera from the perineal structures inferiorly
- Supports the pelvic organs
What does the Pelvic Diaphragm Close Off?
Since it is a “funnel” of skeletal muscles, it closes off the pelvic outlet
What do the Skeletal Muscles of the Pelvic Diaphragm Help With?
They form a dynamic floor that supports the pelvic viscera inferiorly and helps to raise intra-abdominal pressure; voluntary control of urination, fecal continence, and uterus support
Levator ani Muscle consists of three parts according to their fibers:
- Puborectalis
- Pubococcygeus
- Iliococcygeus
Levator ani + Coccygeus Muscles + Their Fascias make…
The Pelvic Diaphragm
Coccygeus is also known as?
Ischiococcygeus
Female pelvic diaphragm permits the passage of what, via what?
Permits the passage of the urethra, vagina, and rectum via the urogenital hiatus
Male pelvic diaphragm permits the passage of the what, via what?
Permits the passage of the urethra and rectum via the urogenital hiatus
Pelvic Arterial Supply
Paired internal iliac arteries and their branches
Pelvic Venous Drainage Parallels the Arterial Blood Supply
Tributaries of the internal iliac veins
How many main arteries enter the lesser pelvis in females vs males?
4 main arteries in the lesser pelvis in females, 3 in males
These types of arteries deliver the most blood to the lesser pelvis, and they bifurcate into an anterior and a posterior division
Paired Internal Iliac Arteries
Pelvic Arteries
- Internal Iliac Arteries
- Paired Ovarian Arteries from the aorta
- Median Sacral Artery
- Superior Rectal Arteries
Pelvic Veins
- Internal Iliac Veins and their tributaries
- Superior Rectal Veins (portal venous system)
- Median Sacral Vein
- Gonadal Veins
Pelvic structures are innervated mainly by?
The sacral (S1-S4) and coccygeal spinal nerves and pelvic part of the autonomic nervous system
Coccygeal Plexus
A small network of nerve fibers formed by the ventral rami of S4 and S5
Pudendal Canal
A horizontal passageway within the obturator fascia which covers the medial aspect of obturator interns; transmits the internal pudendal vessels and pudendal nerve: supply the perineum
Pudendal Nerve
Somatic innervation (S2-S4) to perineal body wall, muscles, genitalia, external anal sphincter and skin of perineum; also carries sympathetics
Perineum
Diamond-shaped pelvic outlet that lies inferior to the inferior pelvic aperture and is bounded by the pubic symphysis anteriorly, ischial tuberosities laterally, coccyx posteriorly
The perineum is subdivided into?
A urogenital (UG) triangle and an anal triangle
The perineum is bounded superiorly by?
Levator ani (pelvic diaphragm) and laterally by obturator internus
Superficial Pouch of the Perineum
Potential space between the membranous layer of subcutaneous tissue and the perineal membrane
Deep Pouch of the Perineum
Bounded inferiorly by the perineal membrane and superiorly and laterally by the fascias of the pelvic diaphragm and obturator interns muscles
Contents of the Superficial Pouch in Males
- Root (crura and bulb) of the penis and associated muscles
- Proximal part of spongy urethra
- Superficial transverse perineal muscles
- Deep perineal branches of internal pudendal vessels and nerves
Contents of the Superficial Pouch in Females
- Clitoris and associated muscles (ischiocavernosus)
- Bulvs of the vestibule and surrounding muscles (bulbospongiosus)
- Superficial transverse perineal muscles
- Greater vestibular gland
Contents of the Deep Pouch in Both Sexes
Contains parts of the urethra centrally, the inferior part of the external urethral sphincter muscle, and the anterior extensions of the sischioanal fat pads
Contents of the Deep Pouch in Males
- Intermediate part of urethra
- Deep transverse perineal muscles
- Bulbourethral glands
- Dorsal neuromuscular structures of the penis
Contents of the Deep Pouch in Females
- Proximal part of urethra
- A mass of smooth muscle
- Dorsal neurovasculature of the…….
Urogenital Diaphragm
The muscles within the deep perineal pouch plus the perineal membrane
Ischioanal Fossa
A fat filled, wedge-shaped region surrounding the rectum and anus; located primarily in the anal triangle between the skin of the anal region and the pelvic diaphragm
Neurovascular Contents of the Ischioanal Fossa
Inferior anal/rectal vessels and nerves and cutaneous branches of the sacral plexus
Disruption of Perineal Body
In women, it provides the final support for the pelvis viscera; if damaged prolapse of the pelvic viscera may occur
