Rectum/Anal Canal Flashcards Preview

Gross II Final > Rectum/Anal Canal > Flashcards

Flashcards in Rectum/Anal Canal Deck (60):
1

The rectum is technically a part of what gastrointestinal structure?

Large intestine (between the sigmoid colon and the anal canal)

2

What is the rectosigmoid junction of the rectum and where is it located?

Upper limit of the rectum located at the middle of the sacrum

3

What is the anorectal junction and where is it located?

The lower limit of the rectum located at the upper border of the pelvic diaphragm

4

What muscles forms a sling around the rectum at the anorectal junction?

Puborectalis

5

What is the rectal ampulla and where is it located?

Dilated terminal portion of the rectum located immediately above the pelvic diaphragm

6

How many transverse rectal folds are there?

Three

7

Does the rectum have mesentery, omental appendices, or haustra?

No.

8

Does the rectum have taeniae coli?

Yes, but it's spread out as a complete layer unlike the intestines

9

Peritoneum covers what parts of the upper third of the rectum?

Front and sides

10

Peritoneum covers what parts of the middle third of the rectum?

Front

11

Peritoneum covers what parts of the lower third of the rectum?

There is no peritoneal covering here

12

The anal canal is between what two structures?

Pelvic diaphragm and anus

13

About how many anal columns lie in the anal canal?

5-10

14

What vascular structures do each anal column contain?

Small branch of the superior rectal artery and a small tributary of the superior rectal vein

15

What are the longitudinal folds of mucosa which lie in the upper half of the anal canal?

Anal columns

16

What are the crescent-shaped folds which connect the lower ends of the anal columns?

Anal valves

17

What are the recesses located between the anal valves and the wall of the anal canal?

Anal sinuses

18

What marks the lower limit of the anal valves around the circumference of the anal canal?

Pectinate line

19

What is the bluish white zone located inferior to the pectinate line?

Anal pecten

20

What is the distal termination of the anal canal where it meets the skin?

Anocutaneous line

21

Which anal sphincter is under involuntary control?

Internal anal sphincter

22

Which anal sphincter is a continuation of the smooth muscle layer of the rectum below the pelvic diaphragm?

Internal anal sphincter

23

What are the three parts of the external anal sphincter?

Subcutaneous, superficial, and deep parts

24

What is the nerve supply of the external anal sphincter?

Nerve to external anal sphincter (S4)

25

What is the function of the external anal sphincter?

Closes anal orifice

26

Which anal sphincter is under voluntary control?

External anal sphincter

27

From where does the superior rectal artery arise?

Inferior mesenteric artery

28

From where does the middle rectal artery arise?

Internal iliac artery

29

From where does the inferior rectal artery arise?

Internal pudendal artery

30

From where does the median sacral artery arise?

Abdominal aorta

31

What arteries make up the blood supply of the rectum and anal canal?

Superior, middle, and inferior rectal arteries and the median sacral artery

32

What are internal hemorrhoids?

Varicosities of the superior rectal vein

33

Internal hemorrhoids cause bulging of what anal structures?

Anal columns

34

Are internal hemorrhoids painful?

No, painless

35

Where do internal hemorrhoids occur?

Above the pectinate line

36

What are external hemorrhoids?

Varicosities of the inferior rectal vein

37

Where do external hemorrhoids occur?

Below the pectinate line

38

Are external hemorrhoids painful?

Can be very painful

39

What are the causes of both types of hemorrhoids?

Pregnancy, heavy lifting, sitting, straining-chronic constipation, portal hypertension

40

Why can heavy lifting cause hemorrhoids?

Due to the increased intra-abdominal presure

41

What would be a possible morbid underlying cause of hemorrhoids?

Portal hypertension

42

What group of people are at a high risk for developing hemorrhoids?

Long distance trunk drivers

43

What is the epithelium like in the anal canal above the pectinate line?

Columnar or cuboidal

44

What is the epithelium like in the anal canal below the pectinate line?

Stratified squamous

45

What is the nerve supply of the anal canal above the pectinate line?

Autonomic fibers

46

What is the nerve supply of the anal canal below the pectinate line?

Pudendal nerve

47

What is the venous supply of the anal canal above the pectinate line?

Superior rectal

48

What is the venous supply of the anal canal below the pectinate line?

Middle, inferior rectal

49

Which lymph nodes are found in the anal canal above the pectinate line?

Internal iliac

50

Which lymph nodes are found in the anal canal below the pectinate line?

Superficial inguinal

51

The upper visceral 2/3 of the anal canal is from which embryologically derived structure?

Hindgut

52

The lower somatic 1/3 of the anal canal is from which embryologically derived structure?

Proctodeum

53

What part of the GI tract accumulates fecal matter?

Sigmoid colon

54

What is usually contained in the rectum?

Nothing; it is usually empty

55

How does the sigmoid colon empty its contents into the rectum?

Through mass peristaltic movement

56

During defecation, what muscles contract to increase pressure within the rectum?

The longitudinal muscle layer of the rectum and the anterior abdominal wall muscles

57

What muscle relaxes during defecation to decrease the angle of the perineal flexure?

Puborectalis

58

What is opened due to the increase in pressure within the rectum during defecation?

Internal anal sphincter

59

What is relaxed under voluntary control during defecation?

External anal sphincter

60

What are the steps of defecation?

1. Sigmoid colon empties contents into rectum by mass peristalsis
2. Muscles contract to increase rectal pressure
3. Puborectalis relaxes
4. Internal anal sphincter opens
5. External anal sphincter relaxes