GB 21. Rectum, Anal Canal, Ischiorectal Fossa

Question 1

What is the blood suppy of the rectum? [main arteries]

Answer 1

[1] Superior Rectal Arteries
[2] Middle Rectal Arteries
[3] Inferior Rectal Arteries

Question 2

Which artery (ies) supply the first half of the anal canal?

Answer 2

Superior Rectal Artery

Question 3

Which artery (ies) supply the lower half of the anal canal?

Answer 3

Middle Rectal Artery + Inferior Rectal Artery

Question 4

What is the venous drainage of the rectum? [main veins]

Answer 4

[1] Superior Rectal Vein
[2] Middle Rectal Vein
[3] Inferior Rectal Vein

Question 5

Which vein(s) drains the first half of the anal canal?

Answer 5

Superior Rectal Vein

Question 6

Which vein(s) drains the second/lower half of the anal canal?

Answer 6

Middle Rectal Vein + Inferior Rectal Vein

Question 7

What are the 3 muscles that make up the Levator Ani muscle?

Answer 7

[1] Iliococcygeus Muscle
[2] Pubococcygeus Muscle (Puborectalis Muscle)
[3] Ischiococcygeus Muscle

Question 8

What nerve innervates the Levator Ani muscles?

Answer 8

Pudendal Nerves

Question 9

What is the Midline Raphe?

Answer 9

where the pubococcygeus muscles insert (into the midline)

Question 10

What is the sensory innervation of the saddle region (what you sit on)?

Answer 10

S2, S3, S4

Question 11

What are the nerve roots that innervate the rectum?

Answer 11

S2, S3, S4

Question 12

What is the Superior Rectal Artery a branch of?

Answer 12

continuation of Inferior Mesenteric Artery

Question 13

What is the Middle Rectal Artery a branch of?

Answer 13

branch of Internal Iliac Artery

Question 14

What is the Inferior Rectal Artery a branch of?

Answer 14

branch of Internal Pudendal Artery

Question 15

Where does the Superior Rectal Vein drain into?

Answer 15

Inferior Mesenteric Vein

Question 16

Where do the Middle and Inferior Rectal Veins drain into?

Answer 16

directly into the inferior vena cava

Question 17

List the POSTERIOR branches of the Internal Iliac Artery in MALES.

Answer 17

[1] Iliolumbar Artery
[2] Lateral Sacral Arteries (2)
[3] Superior Gluteal Artery

Question 18

List the POSTERIOR branches of the Internal Iliac Artery in FEMALES.

Answer 18

[1] Iliolumbar Artery
[2] Lateral Sacral Arteries (2)
[3] Superior Gluteal Artery

Question 19

List the ANTERIOR branches of the Internal Iliac Artery in MALES.

Answer 19

[1] Umbilical Artery 
[2] Obturator Artery
[3] Internal Pudendal Artery
- what comes off of this? 
[4] Inferior Vesical Artery*
[5] Middle Rectal Artery
[6] Inferior Gluteal Artery

Question 20

List the ANTERIOR branches of the Internal Iliac Artery in FEMALES.

Answer 20

[1] Umbilical Artery 
[2] Obturator Artery
[3] Internal Pudendal Artery
[4] Vaginal Artery*
[5] Middle Rectal Artery
[6] Inferior Gluteal Artery 
[7] Uterine Artery

Question 21

What is the common area where the rectum begins in both males and females?

Answer 21

3rd sacral segment

Question 22

Where does the rectum begin and end in males?

Answer 22

Begin: 3rd Sacral Segment
End: Apex Prostate

Question 23

Where does the rectum begin and end in females?

Answer 23

Begin: 3rd Sacral Segment
End: Lower 1/4 of Vagina

Question 24

What are the peritoneal relations of the rectum in all 3 parts?

Answer 24

Upper 1/3: Front + Sides

Middle 1/3: Front Only

Lower 1/3: None

Question 25

What are the rectal valves of Houston? How many rectal valves are there?

Answer 25

they are indentations of the rectum (an inward fold - mucosal folds) Total 3: - 2 on the Left - 1 on the Right

Question 26

What are the posterior relations of the rectum in males?

Answer 26

[1] sacrum + coccyx [2] lower sacral nerves [3] rectal vessels + lymphatics

Question 27

What are the anterior relations of the rectum in males?

Answer 27

[1] upper 2/3s covered by peritoneum [2] coils of small intestine [3] Lower 1/3 (base of bladder, prostate, seminal vesicles)

Question 28

What are the lateral relations of the rectum in males?

Answer 28

supported by the Levator Ani

Question 29

What are the lateral relations of the rectum in females?

Answer 29

supported by the Levator Ani

Question 30

What are the posterior relations of the rectum in females?

Answer 30

[1] sacrum + coccyx [2] lower sacral nerves [3] rectal vessels + lymphatics

Question 31

What are the anterior relations of the rectum in females?

Answer 31

[1] upper 2/3s covered by peritoneum [2] coils of small intestine - lying in Pouch of Douglas (rectum-bladder + rectum-uterus) [3] Lower 1/3 (cervix uteri, vagina)

Question 32

What is the venous anastomoses in the rectum?

Answer 32

between the portal inferior mesenteric vein and the system middle rectal vein

Question 33

What angle is the anorectal junction?

Answer 33

90 degree angle

Question 34

What cell type(s) is/are a part of the upper anal canal?

Answer 34

Coloumnar Cells

Question 35

What cell type(s) is/are a part of the lower anal canal?

Answer 35

Squamous Epithelium

Question 36

What junctions in the body is where coloumnar cells turn into squamous epithelium?

Answer 36

- Esophagus | - rectus to anal to skin

Question 37

Describe the main features of the lining of the anal canal?

Answer 37

[1] Anal Coloumns [2] Anal Sinus [3] Anal Valve

Question 38

What are the 2 distinctive parts of the anal canal?

Answer 38

[1] upper 1/2 lined with mucous membrane | [2] lower 1/2 lined with skin

Question 39

What separates the 2 parts of the anal canal?

Answer 39

dentate line

Question 40

What is the innervation of the upper half of the canal?

Answer 40

autonomic

Question 41

What is the innervation of the lower half of the anal canal?

Answer 41

somatic

Question 42

What is the embryological origin of the upper half of the anal canal?

Answer 42

hindgut

Question 43

What is the embryological origin of the lower half of the anal canal?

Answer 43

anal pit

Question 44

Do both the upper and lower half of the anal canal have the same embryological origin?

Answer 44

No, they do not Upper Half of the Anal Canal - hindgut Lower Half of the Anal Canal - anal pit

Question 45

What is the lymphatic drainage of the upper half of the anal canal?

Answer 45

Inferior Mesenteric Nodes

Question 46

What is the lymphatic drainage of the lower half of the anal canal?

Answer 46

Superficial Inguinal Nodes

Question 47

What type of muscle is the internal sphincter made up of? What is its innervation?

Answer 47

- smooth | - autonomic

Question 48

What type of muscle is the external sphincter made up of? What is its innervation?

Answer 48

- skeletal | - somatic (pudendal nerve S2, S3 + S4)

Question 49

What are the 3 parts that the External Sphincter is made up of?

Answer 49

[1] Deep [2] Superficial [3] Subcutaneous

Question 50

What are the 3 parts that the External Sphincter is made up of?

Answer 50

[1] Deep - puborectalis [2] Superficial - attached to perineal body (in front) and coccyx (at back) [3] Subcutaneous - beneath skin

Question 51

What are fissures?

Answer 51

tears from skin of anal margin to canal

Question 52

What are haemorrhoids?

Answer 52

engorgement of venous plexus

Question 53

What is the structure that allows the rectum to have a sigmoid shape?

Answer 53

Puborectalis Muscle - that loops around the rectum

Question 54

Where is the perineal body located? Where is it located in regards to the urogenital diaphragm?

Answer 54

in the middle line of the perineum at the junction between the urogenital triangle and the anal triangle - located at the back of the diaphragm

Question 55

Where is the urogenital triangle?

Answer 55

- between the 2 ischial tuberosities | - to the pubic symphysis

Question 56

Where is the anal triangle?

Answer 56

- between the 2 ischial tuberosities | - to the coccyx

Question 57

What are the layers of the urogenital diaphragm? What is in it?

Answer 57

[1] Fascia (on top) [2] Deep Perineal Pouch (middle) [3] Perineum (bottom) - urethra + (vagina in females)

Question 58

What is the Pouch of Douglas?

Answer 58

only in FEMALES aka rectouterine pouch - lowest part of body where fluid may collect - if there is pus in there, you need to take a tool up the vagina to drain it

Question 59

What are the pouches near the rectum that females have?

Answer 59

[1] Rectouterine Pouch (important! - Pouch of Douglas) | [2] Vesicouterine Pouch

Question 60

What are the pouch(es) near the rectum that men have?

Answer 60

only one! | - Rectovesical Pouch