Lecture 24 RH

Question 1

Where do the iliac arteries come from? At what level does the aorta split?

Answer 1

1) Abdominal aorta branches at level of L4/5 disk and divides into 2 branches; one to the right and the other to the left.
2) Both branches are called common iliac arteries.
3) Common iliac arteries further branch into internal and external iliac arteries.
* Number here denotes steps along the path of the arteries

Question 2

Where do the veins of the pelvis go and what are they called?

Answer 2

Veins accompany major arteries and are named similar to the arteries. IVC is the point where they meet at L5.

Question 3

What is the iliopectineal line?

Answer 3

rim of the pelvis is the iliopectineal line which separates the true (greater) pelvis from the false (lesser) pelvis.

Question 4

Where do the common iliac arteries split into the internal and external iliac arteries?

Answer 4

at the iliopectineal line.

Question 5

What structures does the internal iliac artery supply?

Answer 5

Viscera

pelvic wall (somatic/parietal branches)

Question 6

What are the other arteries that supply the pelvis?

Answer 6

Branches from outside of the pelvis

ovarian/testicular arteries

Superior rectal (from inferior mesenteric artery) to sigmoid colon and upper rectum.

Median sacral artery

Question 7

Which vein is unusual in the pelvis?

Answer 7

inferior rectal vein is part of portosystemic anastomosis and drains into liver rather than IVC

Question 8

What is interesting about the parietal branches of the internal iliac artery?

Answer 8

Parietal branches of internal iliac are variable in how they form.

Question 9

What are the parietal branches of the internal iliac artery?

Answer 9

Anterior and posterior branches.

Question 10

What does the posterior iliac artery divide into and what does each branch supply?

Answer 10

Iliolumbar: Supplies body wall of iliolumbar region.

Lateral sacral: Supplies lateral sacral region

Superior gluteal: supplies superior gluteal region.

Question 11

What does the anterior iliac artery supply?

Answer 11

Obturator artery: supplies the obturator region

Inferior gluteal:

Internal Pudendal: Supplies the perineal region (including skin), the external genitalia, and the pelvic floor

Question 12

Where does the superior gluteal artery go and how?

Answer 12

Superior gluteal artery goes to the gluteal region and goes through the greater sciatic foramen following piriformis superiorly.

*The superior gluteal nerve also exits at this region.

Question 13

What are the visceral branches of the internal iliac artery?

Answer 13

3 major visceral branches:

Middle rectal:

Uterine: It is tortuous due to enlargement during pregnancy.

Vaginal:

Question 14

What are some organs supplied by end arteries?

Answer 14

Nose

Fingers

Toes

Clitoris

Penis

Question 15

What is the clinical significance of end organs/arteries?

Answer 15

Vasoconstrictor drugs are harmful if injected into end organs.

Question 16

What are the principles underlying veins in the pelvis?

Answer 16

Veins form many plexuses in the pelvic region.

No valves are present.

Question 17

Where do veins of the pelvis drain into?

Answer 17

They drain to tributaries of internal iliac vein which also communicate with internal venous plexus

Question 18

How do cancer cells spread from the prostate?

Answer 18

cancer cells can spread via venous system

Question 19

What is the problem with the prostate venous plexus regarding cancer cells?

Answer 19

Prostatic venous plexus normally drains to tributaries of the IVC. Sacral veins also drain to IVC through holes in the sacrum. As a result, cancer cells could potentially spread to the vertebral column via these veins and through the vertebral column it could spread to other parts of the body.

Question 20

What is the significance of the communication between the inferior mesenteric vein and the liver?

Answer 20

inferior mesenteric vein could potentially take cancer cells to the liver

Question 21

What are portosystemic anastomoses and what is a potential problem that could result from it?

Answer 21

Varices of veins going to the liver could result from blockage of the liver. These varices could potentially fall below anal canal to the exterior. This problem is what causes haemorrhoids.

Question 22

What is the result of distension of blood vessels in rectum + anal canal?

Answer 22

varices in upper part of anal canal generate pressure (discomfort).

Varices in lower part of anal canal generate pain due to somatic innervation of anal canal.

Question 23

How does lymph drain the perineum?

Answer 23

Superficial lymph nodes drain the perineum (anal and urogenital triangles). Superficial lymph nodes drain into deep lymphnodes of the inguinal region (inguinal nodes) and the deep lymph nodes pass near the vertebral column to the left brachiocephalic vein.

Question 24

What lymphatics drain the pelvic viscera?

Answer 24

pelvic viscera drain directly to deep lymph nodes of abdominal region.

Question 25

What is the principle underlying lymphatic drainage of the testis and the scrotum?

Answer 25

Testis and scrotum are drained by vessels that drain the area of their embryological origins.

Testis to nodes on posterior abdominal wall.

Scrotum drains to inguinal nodes.

Question 26

What is a sign of cancer of abdominal viscera or the testis?

Answer 26

Enlargement of the left supraclavicular node (sentinal node).

Question 27

What are the somatic nerves of the pelvis?

Answer 27

Main parietal branches are the obturator nerve and the pudendal nerve.

Question 28

What does the sacral plexus supply?

Answer 28

Sacral plexus (S2 - 4) supplies muscles of the pelvis and gluteal region

Question 29

What is the course of the pudendal nerve before it branches?

Answer 29

Pudendal nerve arises at sacral plexus.

Pudendal nerve enters pelvic cavity via the greater sciatic foramen and then exits via the lesser sciatic foramen.

it then enters fossa in the ischioanal fossa.

Question 30

What are the branches of the pudendal nerve?

Answer 30

Inferior rectal nerve

Penneal + muscular branches

Posterior scrotal nerve

Dorsal nerve of clitoris/penis (also contains cavernous nerves)

Question 31

What does the inferior rectal nerve supply?

Answer 31

External anal sphincter, perianal skin, and anal canal below pectinate line.

Question 32

Does a pudendal nerve block paralyse pelvic floor?

Answer 32

No because nerves have already come off at the location of the block.

Question 33

How is the correct location for a pudendal block found?

Answer 33

Clinician looks for fatty tissue around pudendal canal. Finger is put into vagina to feel for the ischial spine (lesser sciatic foramen)

Question 34

What are the kinds of plexuses found in the pelvis?

Answer 34

Superior hypogastric plexus (sympathetic)

Pelvic splanchnic nerves (Parasympathetic)

Inferior hypogastric plexus (mixed)

Question 35

What is the role of sympathetics and parasympathetics of the pelvis?

Answer 35

Sympathetics contract sphincters and constrict arteries.

Parasympathetics cavernous nerves to smooth muscles in walls of viscera (eg peristalsis and dilation of arteries)

Question 36

Why is there an overlap of neurovascular supply and lymph drainage in perineal structures?

Answer 36

Area which has smooth muscle/epithelial lining is derived from endoderm. They form an interface with the ectoderm structures including skin and skeletal muscle.

Overlap of lymph drainage, blood supply, and nerve supply exist in perineal structures.

Question 37

Where do reflex arcs related to the pelvis take place?

Answer 37

All the main reflexes associated with pelvis and perineal region are related to 3 spinal segments S2,3,4. This includes Micturition, Defaecation, and Erection.

Question 38

How are

Answer 38

Relaxation of involuntary internal urethral sphincter occurs at the level of T12/L1 via sympathetic fibers.

Relaxation of voluntary external urethral sphincter is controlled by S2,3,4

Question 39

Which nervous system control dilation and constriction of blood vessels in the pelvis

Answer 39

Dilation = parasympathetic

Constriction = Sympathetic

Question 40

What is the pelvic pain line?

Answer 40

Line between inferior part of the coccyx and the pubic symphysis called the pelvic pain line. Above this line visceral afferents follow sympathetic fibers and go to T1-L2, below line are pain fibers that follow parasympathetic nerves to S2 - S4.

Question 41

Where does the pain line pass through in the bladder?

Answer 41

Pain line goes through the top of the trigone of the bladder.