Pelvis and Perineum

Question 1

Bony pelvis

Answer 1

basin-shaped bony ring, attaches LL to spine, supports visceral organs of pelvis
- Formed by 4 bones:
1. 2 hip bones (os coxae) – fusion of the ilium, ischium, and pubis – during puberty
2. sacrum
3. coccyx

Question 2

Female pelvis

Answer 2

pelvis is lighter, wider, and shallower than in male.
- it also provides more room in true pelvis

Question 3

Bony pelvis divisions

Answer 3

Greater (false) pelvis and a lesser (true) pelvis, separated by the pelvic brim.
- Greater pelvis – houses certain abdominal viscera.
- Lesser pelvis – accommodates pelvic viscera – bladder and reproductive organs

Question 4

Pelvic ligaments

Answer 4

• Weight of trunk tends to rotate sacrum anteriorly.
• Pelvic ligaments arranged to resist force

Question 5

Pregnancy

Answer 5

pelvic joints and ligaments relax and pelvic
movements increase, relaxation is caused by increase in hormone levels and the presence of the hormone relaxin, sarco-iliac interlocking mechanism less effective since relaxation permits greater rotation of pelvis and contributes to lordotic posture

Question 6

Pelvic diaphragm

Answer 6

• extends from pubic symphysis to coccyx.
• separates pelvic viscera from the perineal structures inferiorly.
• supports the pelvic organs

Question 7

PD part 2

Answer 7

“funnel” of skeletal muscles (levator ani) closing off pelvic outlet.
- These muscles form a dynamic floor that supports pelvic viscera inferiorly and helps raise intra-abdominal pressure; voluntary control of urination, fecal continence (via puborectalis), and uterus support

Question 8

PD muscles

Answer 8

Levator ani muscle consists of 3 parts named according to attachments of their fibers:
- puborectalis
- pubococcygeus
- iliococcygeus
- Coccygeus (or ischiococcygeus)

Question 9

Male and female PD

Answer 9

• Female pelvic diaphragm permits passage of urethra, vagina, and rectum via urogenital hiatus.
• Male pelvic diaphragm permits the passage of the urethra and rectum via the urogenital hiatus

Question 10

Pelvic blood supply

Answer 10

• Arterial supply: paired internal iliac arteries and their branches.
• Venous drainage parallels arterial
  blood supply: tributaries of internal IVs

Question 11

Pelvic arteries

Answer 11

(4) female, (3) male:
- paired internal iliac arteries deliver most blood to lesser pelvis, they bifurcate into an A and a P division
- paired ovarian arteries from the aorta
- superior rectal arteries

Question 12

Pelvic veins

Answer 12

mainly internal iliac veins and tributaries
- S rectal veins (portal venous system)
- gonadal veins

Question 13

Pelvic nerves

Answer 13

sacral (S1-S4) and coccygeal spinal nerves and pelvic part of ANS

Question 14

Sacral plexus

Answer 14

(sciatic nerve {# 1}, pudendal nerve {# 7} – the main nerve of the perineum and chief sensory nerve of the external genitalia, superior {# 2} and inferior gluteal nerves)

Question 15

Coccygeal nerves

Answer 15

a small network of nerve fibers formed by the ventral rami of S4 and S5

Question 16

Pudendal canal

Answer 16

horizontal passageway within obturator
fascia which covers M aspect of obturator internus, transmits internal pudendal vessels and pudendal nerve: supply the perineum.

Question 17

Pudendal nerve

Answer 17

somatic innervation (S2-4) to perineal body
wall, muscles, genitalia, external anal sphincter and skin of perineum; also carries
sympathetic

Question 18

Perineum

Answer 18

Diamond-shaped pelvic outlet that lies I to the I pelvic aperture
- Bounded by pubic symphysis A, ischial tuberosities L, coccyx P
- Subdivided into urogenital (UG) triangle and an anal triangle

Question 19

Perineum part 2

Answer 19

bounded S by levator ani (pelvic diaphragm) and L by obturator internus

Question 20

Male perineum: Superficial

Answer 20

• root (crura and bulb) of penis
  and ischiocavernosus and bulbospongiosus
• proximal part of spongy urethra
• superficial transverse perineal muscles
• deep perineal branches of internal pudendal vessels/nerves
• Urethra

Question 21

Male perineum: Deep

Answer 21

• Urethra
• External urethra sphincter
• Dorsal neurovascular of the penis
• Deep transverse perineal muscle
• Bulbourethral glands

Question 22

Female perineum: Superficial

Answer 22

• clitoris and ischiocavernosus
• bulbs of vestibule and bulbospongiosus
• superficial transverse perineal muscles
• greater vestibular gland
• deep perineal branches of internal pudendal vessels and nerves

Question 23

Female perineum: Deep

Answer 23

• Dorsal neurovascular of the clitoris.
• Deep transverse perineal muscle
• Urethra
• External urethral sphincter

Question 24

Ischioanal Fossa – Anal Triangle

Answer 24

fat-filled, wedge-shaped region, surrounds rectum and anus, located in anal triangle between skin of anal region and PD
- Neurovascular contents: I anal/rectal vessels and nerves and cutaneous branches of sacral plexus

Question 25

Disruption in female perineum

Answer 25

a significant structure because it provides the final support for the pelvis viscera, stretching or tearing of this attachment of the perineal muscles from perineal body can occur during childbirth, removing support provided by pelvic floor. As a result, prolapse of pelvic viscera through urethra or vaginal orifice can occur