Anatomy of Lateral Pelvic Wall and Pelvic Mass

Question 1

What three bones combine to make up the lateral pelvic wall?

Answer 1

Ilium
ischium
pubis

Question 2

What membrane and ligaments are found on top of the lateral pelvic wall?

Answer 2

Sacrotuberous Ligament
Sacrospinous ligament
Obturator membrane

Question 3

What muscles are found on the lateral pelvic wall?

Answer 3

Levator Ani
Coccygeus
Piriformis (covered by descending sacral plexus)
Obturator internus (partially covered by tendinous arch of levator ani)

Question 4

The majority of arteries of pelvis and perineum arise from which artery?

Answer 4

internal iliac artery

Question 5

What are the exceptions to the pelvic blood supply which do not come from the internal iliac artery?

Answer 5

Gonadal artery - from L2 level of abdominal aorta

Superior rectal artery - from inferior mesenteric (IMA)

Question 6

The internal iliac goes on to divide into an anterior and posterior division. Explain what arteries are found in each division in male patients.

Answer 6

ANTERIOR

• obturator artery
• remnant of medial umbilical ligament
• superior and inferior vesical (+ prostatic branch of IV)
• Internal pudendal
• middle rectal

POSTERIOR
- gluteal arteres

Question 7

How does the internal pudendal artery terminate in the male?

Answer 7

End arteries are

• dorsal artery of penis
• posterior scrotal artery (previously perineal)

Question 8

Where does the anterior scrotal artery originate from?

Answer 8

External iliac

Question 9

The internal iliac goes on to divide into an anterior and posterior division. Explain what arteries are found in each division in female patients.

Answer 9

ANTERIOR
- obturator artery
- medial umbilical ligament
- superior vesical arteries
(women thought to not have inferior vesical artery - but this is not true)
- uterine artery
- vaginal artery (thought to supply territory of inferior vesical)
- internal pudendal
- middle rectal

POSTERIOR
- gluteal arteries

Question 10

What important anastomoses occur between arteria supplies in the pelvis

Answer 10

• uterine artery and the ovarian artery

- uterine artery and the vaginal artery

Question 11

HOw does the female arterial supply to the pelvis terminate?

Answer 11

dorsal artery of clitoris
labial arteries (from perineal)

Question 12

Explain how the venous drainage in the pelvis is arranged

Answer 12

• follows arterial system (named as per arteries)
• venous plexuses
• Drain mainly to internal iliac vein
• some drain via superior rectal into Hepatic Portal system
• some will drain via lateral sacral veins into internal vertebral venous plexus

Question 13

What is the disadvantage of the close communication between the lateral sacral veins and the internal vertebral venous plexus?

Answer 13

• infection can track easily

- cancerous spread

Question 14

What nerves are found on the lateral pelvic side wall?

Answer 14

• Obturator (from lumbar plexus)
• Sacral Plexus (combining to form sciatic)
• Pudendal
• Pelvic splanchnic nerves (for parasympathetics)
• Nerve to levator ani

Question 15

To which groups of lymph nodes do the superior parts of the pelvic organs drain?

Answer 15

• external iliac nodes -> common iliac

Question 16

To which groups of lymph nodes do the inferior parts of the pelvic organs drain?

Answer 16

• internal iliac nodes first -> common iliac

Question 17

Where does the lymph from superficial parts of the perineum drain to and why is this?

Answer 17

• superficial inguinal nodes

- Parietal (skin) not visceral structure

Question 18

Why is it difficult to map a direction of cancer spread in the pelvis?

Answer 18

• lymphatics have high cross-over
  => cancer can spread in any direction
• pattern not sufficiently predictable to anticipate spread

Question 19

What is meant by “trans-peritoneal spread”?

Answer 19

• usually infections in abdomen and pelvis are kept seperate by layer of peritoneum
• if thin peritoneum is invaded and infection passes through, then due to its draping nature across all pelvic organs, it acts as a means to spread infection

Question 20

What is the clinical importance of the pre-sacral venous plexus?

Answer 20

Can cause traumatic haemorrhage if injured during surgical procedure

Question 21

What structure should be avoided when ligating the uterine artery to perform a hysterectomy?

Answer 21

Ureter (in close proximity)