Rectum and anal canal

Question 1

What does partially retroperitoneal mean in terms of the rectum?

Answer 1

Has mesorectum, not mesentary

Question 2

Where does the rectum begin?

Answer 2

In front of the 3rd sacrum and cocyx

Question 3

Where does the rectum end?

Answer 3

In front of the tip of the cocyx by piercing the pelvic diaphragm and becoming continous with the anal canal

Question 4

What does the lower part of the rectum expand to form?

Answer 4

Rectal ampulla

Question 5

What do lateral curvatures of the rectum coincide with?

Answer 5

Rectal folds or valves internally

Question 6

What lies on both sides of the rectum?

Answer 6

Pararectal fossa

Question 7

What are present in the colon which are not in the rectum?

Answer 7

• Lacks taenia
• Haustra
• Epiploic appendices

Question 8

How many transverse mucosal folds do not disappear when rectum is distended and what do they do?

Answer 8

3 (slow down passage of feces and prevent overdistention)

Question 9

What is the junction between the rectum and anal canal called?

Answer 9

Perineal flexure (anorectal junction or angle or line)

Question 10

What is the perineal flexure caused by?

Answer 10

Anterior pull of the rectum by puborectal muscle

Question 11

What pouch lies anterior to the rectum in males?

Answer 11

Rectovesicle pouch

Question 12

What can be damaged in rectal surgery?

Answer 12

Pelvic plexus

Question 13

What is patholigically significant about the prostatic venous plexus?

Answer 13

Connects to vertebral plexus has no valves -> metastases from prostate to vertebrae

Question 14

WHat fascia lies anterior to the rectum in males?

Answer 14

Rectoprostatic fascia (Denoviller’s fascia)

Question 15

What is anterolateral to the rectum in men?

Answer 15

• Ductus deferens
• Seminal vesicles
• Ureter

Question 16

What is the anal canal surrounded by?

Answer 16

• Levator ani

- External and internal anal sphincter

Question 17

What is the muscular structure which lies at the junction of the anal canal and rectum?

Answer 17

Anorectal ring

Question 18

What does division of the anorectal ring result in?

Answer 18

Incontinance (can be a resut of childbirth or surgery)

Question 19

What muscle does the anal canal include?

Answer 19

Puborectalis sling

Question 20

Describe the internal anal sphincter

Answer 20

• Smooth muscle, autonomic
• Derived from circular muscle layer
• Ends at interspinecteric groove

Question 21

Describe the external anal sphincter

Answer 21

• Striated muscle
• One functional unit with deep, superficial and subcutaneous parts
• Fuses with puborectalis

Question 22

What does the external anal sphincter fuse with?

Answer 22

Puborectalis

Question 23

What are the 8-10 longitudinal folds called which are located in the upper part of the anal canal?

Answer 23

Anal columns

Question 24

What are the anal columns formed by and what do they contain?

Answer 24

Branches of the superior rectal vein

• Superior rectal artery
• Lymphatics
• Nerves

Question 25

What do anal columns unite with each other inferiorly to create?

Answer 25

Anal valves

Question 26

What is superior to each anal valve?

Answer 26

Anal sinus (crypt) - Mucous glands - Lubricates feces

Question 27

What do the anal valves together form?

Answer 27

A circle in the anal canal called the pectinate (dentate) line (anal membrane in the fetus)

Question 28

What is above the pectinate (dentate) line?

Answer 28

Hemorrhoidal zone (derived from mesoderm)

Question 29

WHat is inferior to the pectinate (dentate) line?

Answer 29

Transition zone known as the anal pecten

Question 30

What is the anal pecten supplied by?

Answer 30

- Inferior rectal nerve | sensitive to pain, temperature, touch, pressure

Question 31

Where does the anal pecten end inferiorly?

Answer 31

``` Anocutaneous line ("white line") (where lining of the anal canal becomes the skin) Also coincides to groove with internal and external anal sphincters ```

Question 32

What does the pectinate (dentate) line mark the end of in the fetus?

Answer 32

The hindgut (endoderm)

Question 33

Where is the pectinate (dentate) line located?

Answer 33

A third of the way up the anal canal | - divides upper 2/3s and lower 1/3 of anal canal

Question 34

What is the epithelia of the anal pecten?

Answer 34

Stratified squamus non-keratinised

Question 35

What artery supplies the superior 1/3 of the rectum and anal canal?

Answer 35

Inferior mesenteric artery | -> superior rectal artery

Question 36

What artery supplies the middle 1/3 of the rectum and anal canal?

Answer 36

Internal iliac | -> Middle rectal (varibale)

Question 37

What artery supplies below the anorectal line?

Answer 37

Internal pudendal | -> Inferior rectal artery

Question 38

What artery contribution can cause bleeding during surgery around rectum and anus?

Answer 38

Median sacral

Question 39

What layer is the internal rectal plexus found

Answer 39

Submucosa

Question 40

Where does the internal rectal plexus drain to?

Answer 40

Superior rectal vein

Question 41

Where is the external venous plexus found?

Answer 41

Between and outside muscle layer

Question 42

Where does the superior 1/3 of the external venous plexus drain?

Answer 42

Superior rectal - > Inferior mesenteric - > Hepatic portal vein

Question 43

Where does the middle 1/3 of the external venous plexus drain?

Answer 43

Middle rectal | -> internal iliac + internal pudendal veins

Question 44

Where does the inferior 1/3 of the external venous plexus drain?

Answer 44

Inferior rectal | -> internal iliac + internal pudendal veins

Question 45

Where does lymph drain from the superior rectum?

Answer 45

Inferior mesenteric nodes

Question 46

Where does lymph drain from inferior rectum and proximal anal canal?

Answer 46

Internal iliac nodes

Question 47

Where does lymph drain from the distal anal canal?

Answer 47

Superficial inguinal nodes

Question 48

What do the parasympathetics from S2-4 via pelvic splanchnic nerves -> pelvic (inferior hypogastric) plexus do?

Answer 48

- Increase peristaltism - Relax anal sphincter - Visceral senses

Question 49

What is the function of the sympathetics from L1-2(3) via lumbar splanchnic nerves?

Answer 49

Contract anal sphincter

Question 50

What are the haemorrhoidal veins also known as?

Answer 50

Rectal veins

Question 51

What is the most common cause of haemorrhoids in females?

Answer 51

Pregnancy

Question 52

What are anal cushions?

Answer 52

- Anal columns which are bigger in lithotomy position - They are present at 3, 7, 11 o'clock - Help anal sphincters close lumen