Rectum and anal canal Flashcards

1
Q

What does partially retroperitoneal mean in terms of the rectum?

A

Has mesorectum, not mesentary

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2
Q

Where does the rectum begin?

A

In front of the 3rd sacrum and cocyx

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3
Q

Where does the rectum end?

A

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

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4
Q

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

A

Rectal ampulla

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5
Q

What do lateral curvatures of the rectum coincide with?

A

Rectal folds or valves internally

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6
Q

What lies on both sides of the rectum?

A

Pararectal fossa

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7
Q

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

A
  • Lacks taenia
  • Haustra
  • Epiploic appendices
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8
Q

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

A

3 (slow down passage of feces and prevent overdistention)

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9
Q

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

A

Perineal flexure (anorectal junction or angle or line)

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10
Q

What is the perineal flexure caused by?

A

Anterior pull of the rectum by puborectal muscle

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11
Q

What pouch lies anterior to the rectum in males?

A

Rectovesicle pouch

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12
Q

What can be damaged in rectal surgery?

A

Pelvic plexus

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13
Q

What is patholigically significant about the prostatic venous plexus?

A

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

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14
Q

WHat fascia lies anterior to the rectum in males?

A

Rectoprostatic fascia (Denoviller’s fascia)

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15
Q

What is anterolateral to the rectum in men?

A
  • Ductus deferens
  • Seminal vesicles
  • Ureter
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16
Q

What is the anal canal surrounded by?

A
  • Levator ani

- External and internal anal sphincter

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17
Q

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

A

Anorectal ring

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18
Q

What does division of the anorectal ring result in?

A

Incontinance (can be a resut of childbirth or surgery)

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19
Q

What muscle does the anal canal include?

A

Puborectalis sling

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20
Q

Describe the internal anal sphincter

A
  • Smooth muscle, autonomic
  • Derived from circular muscle layer
  • Ends at interspinecteric groove
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21
Q

Describe the external anal sphincter

A
  • Striated muscle
  • One functional unit with deep, superficial and subcutaneous parts
  • Fuses with puborectalis
22
Q

What does the external anal sphincter fuse with?

A

Puborectalis

23
Q

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

A

Anal columns

24
Q

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

A

Branches of the superior rectal vein

  • Superior rectal artery
  • Lymphatics
  • Nerves
25
Q

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

A

Anal valves

26
Q

What is superior to each anal valve?

A

Anal sinus (crypt)

  • Mucous glands
  • Lubricates feces
27
Q

What do the anal valves together form?

A

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

28
Q

What is above the pectinate (dentate) line?

A

Hemorrhoidal zone (derived from mesoderm)

29
Q

WHat is inferior to the pectinate (dentate) line?

A

Transition zone known as the anal pecten

30
Q

What is the anal pecten supplied by?

A
  • Inferior rectal nerve

sensitive to pain, temperature, touch, pressure

31
Q

Where does the anal pecten end inferiorly?

A
Anocutaneous line ("white line") (where lining of the anal canal becomes the skin)
Also coincides to groove with internal and external anal sphincters
32
Q

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

A

The hindgut (endoderm)

33
Q

Where is the pectinate (dentate) line located?

A

A third of the way up the anal canal

- divides upper 2/3s and lower 1/3 of anal canal

34
Q

What is the epithelia of the anal pecten?

A

Stratified squamus non-keratinised

35
Q

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

A

Inferior mesenteric artery

-> superior rectal artery

36
Q

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

A

Internal iliac

-> Middle rectal (varibale)

37
Q

What artery supplies below the anorectal line?

A

Internal pudendal

-> Inferior rectal artery

38
Q

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

A

Median sacral

39
Q

What layer is the internal rectal plexus found

A

Submucosa

40
Q

Where does the internal rectal plexus drain to?

A

Superior rectal vein

41
Q

Where is the external venous plexus found?

A

Between and outside muscle layer

42
Q

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

A

Superior rectal

  • > Inferior mesenteric
  • > Hepatic portal vein
43
Q

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

A

Middle rectal

-> internal iliac + internal pudendal veins

44
Q

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

A

Inferior rectal

-> internal iliac + internal pudendal veins

45
Q

Where does lymph drain from the superior rectum?

A

Inferior mesenteric nodes

46
Q

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

A

Internal iliac nodes

47
Q

Where does lymph drain from the distal anal canal?

A

Superficial inguinal nodes

48
Q

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

A
  • Increase peristaltism
  • Relax anal sphincter
  • Visceral senses
49
Q

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

A

Contract anal sphincter

50
Q

What are the haemorrhoidal veins also known as?

A

Rectal veins

51
Q

What is the most common cause of haemorrhoids in females?

A

Pregnancy

52
Q

What are anal cushions?

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