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Gross III > Part III: Rectum Pg 109-112 > Flashcards

Part III: Rectum Pg 109-112 Flashcards

1
Q

Pelvic end of alimentary tract where feces accumulate prior to defecation

A

Rectum

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2
Q

Rectosigmoid junction located anterior to what vertebral level

A

S3

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3
Q

Is the rectum intraperitoneal, retroperitoneal or extraperitoneal or sub peritoneal?

A
  • Superior third of rectum is retroperitoneal

- Inferior third of rectum is subperitoneal

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4
Q

What happens to the teniae coli as the transition from sigmoid colon to rectum?

A

Teniae coli of sigmoid colon expand into continuous layer on rectum

NOTE: Epiploic appendages, haustra and sacculations are also absent from rectum

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5
Q

What is the sacral flexure?

A

Where the rectum follows contour of sacrum and coccyx

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6
Q

What is the anorectal flexure?

A

Where the rectum takes a sharp turn at coccyx and pierces pelvic diaphragm

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7
Q

What is the functional significance of the anorectal flexure?

A

Approximately 80 degree posterior turn important for maintaining fecal continence

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8
Q

What maintains the 80 degree posterior turn of the anorectal flexure?

A

tonus of Puborectalis M at rest

  • Puborectalis M must actively contract to resist peristaltic contractions in rectum and prevent defecation
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9
Q

Conscious initiation of defecation requires:

A

relaxation of Puborectalis M

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10
Q

3 sharp lateral flexures are present in rectum (superior, intermediate, inferior) and correspond to:

A

Transverse Rectal Folds of mucosa and submucosa

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11
Q

dilatable terminal region of the rectum lying above and supported by Levator Ani M

A

Ampulla

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12
Q

What is the function of the ampulla of the rectum?

A

Relaxes to hold accumulating fecal material prior to defecation

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13
Q

What is the function of the rectovesical pouch (in males), rectouterine pouch (in females) and pararectal fossae (in both sexes)?

A

All of these provide space for rectum to distend as it fills with feces

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14
Q

Posteriorly in both sexes, the rectum is associated with:

A
  • Sacral vertebrae and coccyx
  • Sacral plexuses and inferior ends of sympathetic trunks
  • Median Sacral AV
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15
Q

Anteriorly in males, the rectum is associated with:

A
  • Fundus of urinary bladder and terminal parts of ureters
  • Ductus deferens, seminal vesicles and prostate
  • Separated from these structures by rectovesical pouch
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16
Q

Anteriorly in females, their rectum is associated with

A
  • Vagina, posterior fornix and cervix of uterus

- Separated from these structures by rectouterine pouch

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17
Q

What is the arterial supply to the proximal part of rectum?

A

Superior Rectal A - branches from Inferior Mesenteric A

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18
Q

What is the arterial supply to the anorectal junction and anal canal of the rectum?

A

Inferior Rectal A - branches from Internal Pudendal A

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19
Q

There are three arteries that supply the rectum. What are they?

A
  • Superior Rectal A - branches from Inferior Mesenteric A
  • Middle Rectal A - branches from Internal Iliac (anterior division)
  • Inferior Rectal A - branches from Internal Pudendal A
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20
Q

What is the venous drainage of the rectum?

A
  • Superior Rectal V drains to hepatic portal venous system
  • Middle and inferior Rectal V drain to systemic system via Internal Iliac V
  • Anastomoses between these veins create an important portacaval anastomosis
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21
Q

Lymphatic drainage of superior portion of the rectum is through:

A

pararectal to inferior mesenteric and lumbar nodes

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22
Q

Lymphatic drainage of inferior portion of the rectum is through:

A

internal iliac lymph nodes

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23
Q

Sympathetic innervation of the rectum is via:

A

lumbar splanchnic N through superior hypogastric plexus

NOTE: Possibly vasomotor but not functionally significant

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24
Q

Parasympathetic innervation of the rectum is via:

A

pelvic splanchnic N through inferior hypogastric plexus

25
Q

Parasympathetic innervation to the rectum function:

A

Motor fibers to rectal muscularis externa

26
Q

Visceral afferents (conveying both pain and/or distension) from the rectum pass through

A

pelvic splanchnic N to S2-S4

27
Q

What happens to anal sphincters when the ampulla is empty?

A
  • Internal Anal Sphincter M is contracted

- External Anal Sphincter M is relaxed

28
Q

Defecation is controlled by innervation mediated through:

A

pelvic splanchnic N

29
Q

When feces accumulates in ampulla and sufficiently distends it, what happens to the anal sphincters?

A
  • Internal Anal Sphincter M reflexively relaxes

- External Anal Sphincter M reflexively contracts

30
Q

What initiates the external anal sphincter M to reflexively contract?

A

visceral afferents in pelvic splanchnic N

31
Q

Defecation requires voluntary override of:

A

reflexive External Anal Sphincter M contraction

NOTE: Puborectalis M also must voluntarily relax

32
Q

Parasympathetic stimulation to the rectum during defecation does what?

A

increases peristaltic activity in rectum

33
Q

The terminal part of large intestine (approximately 3cm) that extends from pelvic diaphragm (Puborectalis M) to anus

A

Anal canal

34
Q

Thickened circular smooth muscle around the superior two-thirds of anal canal

A

Internal Anal Sphincter

35
Q

Is the internal anal sphincter under voluntary or involuntary control?

A

Involuntary

NOTE: Normally contracted (sympathetic) to prevent leakage of feces or flatus but reflexively relaxes in response to pressure of feces/gas in rectal ampulla

36
Q

Broad band of skeletal muscle surrounding inferior two-thirds of anal canal

A

External Anal Sphincter

37
Q

Is the external anal sphincter under voluntary or involuntary control?

A

Voluntary

38
Q

The external anal sphincter is attached anteriorly to ______ & posteriorly to _______.

A
  • perineal body

- coccyx (via anococcygeal L)

39
Q

The external anal sphincter blends superiorly with:

A

Puborectalis M

40
Q

What voluntarily contracts to prevent defecation or relax to allow defecation?

A

External anal sphincter and puborectalis M

41
Q

What innervates the external anal sphincter?

A

Inferior Rectal N (S4) from Pudendal N

42
Q

longitudinal ridges of mucosa in superior half of anal canal

A

Anal columns

43
Q

What part of the anus contains terminal branches of Superior Rectal AV

A

Anal Columns

44
Q

What landmark is located at superior ends of anal columns

A

Anorectal Junction

45
Q

What structure is located at inferior ends of anal columns

A

Anal Valves

46
Q

The small recesses located just superior to anal valves in the anal columns that produce mucous to facilitate passage of feces

A

Anal sinuses

47
Q

irregular line formed by anal valves

A

Pectinate lines

48
Q

What is the arterial supply to the anal canal above the pectinate line?

A

Superior Rectal A (from Inferior Mesenteric A)

NOTE: Middle Rectal A forms anastomoses with Superior/Inferior Rectal A

49
Q

What is the arterial supply to the anal canal below the pectinate line?

A

Inferior Rectal A (from Internal Pudendal A)

NOTE: Middle Rectal A forms anastomoses with Superior/Inferior Rectal A

50
Q

What is the venous drainage of the anal canal superior to pectinate line?

A

Hepatic portal system via Superior Rectal V

51
Q

What is the venous drainage of the anal canal inferior to pectinate line?

A

IVC via Inferior Rectal V, Internal Pudendal V

52
Q

What is the lymphatic drainage of the anal canal superior to pectinate line?

A

internal iliac lymph nodes

53
Q

What is the lymphatic drainage of the anal canal inferior to pectinate line?

A

superficial inguinal lymph nodes

54
Q

Autonomic innervation to the anal canal above the pectinate line is via:

A

inferior hypogastric plexus

55
Q

Sympathetic innervation of the anal function:

A

maintain tonus of Internal Anal Sphincter

56
Q

Parasympathetic innervation of the anal canal function:

A

relax Internal Anal Sphincter and initiate peristalsis

57
Q

Sympathetic and parasympathetic innervation is responsive to”

A

distension/stretching but insensitive to touching/cutting

58
Q

Somatic innervation of the anal canal below pectinate line is via:

A

Inferior Rectal N (Pudendal N)

59
Q

Somatic innervation to the anal canal function:

A
  • Motor innervation to External Anal Sphincter

- Responsive to pain, touch, temperature

Gross III (20 decks)

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