Pelvic Floor, Vessels and Nerves

Question 1

At what vertebral level does the aorta bifurcate? What vessels are formed?

Answer 1

L4

Left and right common iliac arteries

Question 2

The common iliac arteries each split giving two further arteries: the internal and external iliac arteries. What happens to the external iliac artery?

Answer 2

Gives off the inferior epigastric artery before passing deep to the inguinal ligament and becoming the femoral artery of the lower limb

Question 3

The inferior epigastric artery ascends on the anterior abdominal wall and anastomoses with which vessel?

Answer 3

Superior epigastric artery

Question 4

The internal iliac artery supplies most of the pelvic viscera, the pelvic and lower abdominal walls and the perineum, as well as sending branches to the lower limb.

Which other arteries supply pelvic structures?

Answer 4

Gonadal

Ureteric

Inferior mesenteric artery

Question 5

What structure forms the median umbilical ligament?

Answer 5

Urachus

Question 6

What structure forms the medial umbilical ligament?

Answer 6

Umbilical artery

Question 7

What structure forms the lateral umbilical ligament?

Answer 7

Inferior mesenteric artery

Question 8

In a male, what is supplied by the inferior vesical artery?

Answer 8

Bladder and prostate

Question 9

Which branches of the internal iliac artery pass out of the pelvis? What do they supply?

Answer 9

Superior and inferior gluteal arteries, supply gluteal region

Internal pudendal artery, supplies the perineum

Question 10

Through which structure does the internal pudendal artery leave the pelvis?

Answer 10

Greater sciatic foramen

Question 11

Which branches of the internal pudendal artery supply the erectile tissues of the penis?

Answer 11

Dorsal arteries of penis, deep arteries of penis, arteries of bulb of penis

Question 12

Which branches of the internal pudendal artery supply the erectile tissues of the clitoris and vestibule?

Answer 12

Dorsal arteries of clitoris, deep arteries of clitoris

Question 13

Into which vessels do the gonadal veins drain?

Answer 13

Left: Left renal vein

Right: IVC

Question 14

Lymph from majority of pelvic viscera drains into which nodes?

Answer 14

Internal iliac lymph nodes

Question 15

The internal iliac nodes drain into which nodes?

Answer 15

External iliac nodes, then pre-aortic nodes

Question 16

Into which lymph nodes do the gonads drain?

Answer 16

Left and right lumbar lymph nodes

Question 17

What nerves are present in the pelvis?

Answer 17

Obturator nerve

Sacral plexus (and branches)

Sympathetic nerves

Parasympathetic nerves

Question 18

The sacral plexus is formed by the ventral rami of __?__

Answer 18

the first four sacral nerves, as well as L4 and L5

Question 19

The sciatic and pudendal nerves are branches from __?__

Answer 19

sacral plexus

Question 20

The sciatic and pudendal nerves leave the pelvis via __?__

Answer 20

the greater sciatic foramen

Question 21

Within the pelvis, the sacral plexus supplies the muscle of __1__ and gives rise to a parasympathetic outflow, the __2__ nerves (stemming from __3__).

Answer 21

1) the pelvic floor
2) pelvic splanchnic
3) S2-S4

Question 22

Sympathetic fibres to pelvic viscera are supplied by the __1__ and __2__ nerves, which branch off the __3__, eventually joining the pelvic plexus.

Answer 22

1) thoracic splanchnic
2) lumbar splanchnic
3) sympathetic chain

Question 23

From where does the piriformis muscle arise?

Answer 23

Anterior aspect of sacrum

Question 24

After arising from the sacrum, what path does the piriformis muscle take?

Answer 24

Leaves pelvic cavity via the greater sciatic foramen, inserting at greater trochanter of femur

Question 25

From where does the obturator internus muscle originate?

Answer 25

Deep surface of obturator membrane and the bone surrounding the obturator foramen

Question 26

After arising from the obturator membrane and the bone surrounding the obturator foramen, what path does the obturator internus muscle take?

Answer 26

Leaves pelvic cavity via the lesser sciatic foramen, inserting at greater trochanter of femur

Question 27

What are the actions of piriformis and obturator internus?

Answer 27

Lateral rotation and abduction of femur at hip joint

Question 28

What travels through the obturator canal?

Answer 28

Obturator neurovascular bundle (artery, vein, nerve)

Question 29

What does the pelvic floor separate?

Answer 29

Pelvic cavity and perineum

Question 30

What muscles form the pelvic floor?

Answer 30

Levator ani anteriorly and coccygeus muscle posteriorly on each side

Question 31

The two levator ani muscles are attached laterally to the pelvic wall; to which structures?

Answer 31

Ischial spine, tendinous arch, pubic bone

Question 32

The two levator ani muscles converge in the midline. How are they arranged?

Answer 32

They interdigitate around the urogenital and anal hiatuses

Question 33

What is the perineal body? What is its function?

Answer 33

Fibrous structure posterior to urogenital hiatus and in front of rectum. Point of convergence for levator ani muscles.

Helps to stabilise the pelvic floor

Question 34

What are the attachments of coccygeus muscle?

Answer 34

Ischial spine to sacrum and coccyx

Question 35

What structure is adhered to the gluteal surface of coccygeus muscle?

Answer 35

Sacrospinous ligament

Question 36

Which muscle forms a sling around the rectum? What is its function?

Answer 36

Puborectalis muscle.

Pulls the gut tube forwards so that the anal canal descends at an angle of approximately 90 degrees to the rectum. This angle is important in maintaining faecal continence

Question 37

What is an episiotomy? When and why is it carried out?

Answer 37

A cut through the pelvic floor between the vagina and rectum (perineal body) to enlarge the vaginal canal.

Question 38

What happens to the angle between the anal canal and rectum when the puborectalis muscle relaxes? Does this aid or inhibit defecation?

Answer 38

When puborectalis relaxes, the angle increases - becomes more obtuse; allowing defecation.

When it contracts, angle becomes more acute.