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Anatomy Topnotch > 10. Rectum and Anus > Flashcards

10. Rectum and Anus Flashcards

1
Q

is the most distal segment of the large intestine, and has an important role as a temporary store of faeces.

A

rectum

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2
Q

The rectum begins at the level of the

A

S3

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3
Q

How is Rectum

macroscopically distinct from the colon

A
  1. absence of taenia coli
  2. absence of haustra
  3. absence of omental appendices
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4
Q

course of the rectum is marked by two major flexures:

A
  1. sacral flexure

2. anorectal flexure

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5
Q

the course of the rectum, is marked by these three additional lateral flexures

A

superior,
intermediate,
inferior

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6
Q

anteroposterior curve with concavity anteriorly (follows the curve of the sacrum and coccyx).

A

sacral flexures

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7
Q

three lateral flexures (superior, intermediate and inferior) of the rectum are formed by

A

transverse folds of the internal rectum wall.

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8
Q

final segment of the rectum

A

ampulla

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9
Q

relaxes to accumulate and temporarily store faeces until defecation occurs.

A

ampulla

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10
Q

peritoneum covering of the rectum

A
  • superior third of the rectum – the anterior surface and lateral sides are covered by peritoneum.
  • The middle third – anterior peritoneal covering
  • lower 1/3 – no peritoneum associated with it.
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11
Q

In males, the reflection of peritoneum from the rectum to the posterior bladder wall forms the

A

rectovesical pouch

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12
Q

In females, the peritoneum reflects to the posterior vagina and cervix, forming the

A

rectouterine pouch (pouch of Douglas)

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13
Q

rectum receives arterial supply through three main arteries:

A

Superior rectal artery – terminal continuation of the inferior mesenteric artery.
Middle rectal artery – branch of the internal iliac artery.
Inferior rectal artery – branch of the internal pudendal artery.

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14
Q

venous drainage of the recum is via

A

superior r.v -> portal venous system

middle and inferior rectal veins -> systemic venous system

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15
Q

Anastomoses between the portal and systemic veins are located in the wall of anal canal, making this a site of

A

portocaval anastomosis.

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16
Q

innervation of the rectum

A

Sympathetic nervous supply to the rectum is from the lumbar splanchnic nerves and superior and inferior hypogastric plexuses.

Parasympathetic supply is from S2-4 via the pelvic splanchnic nerves and inferior hypogastric plexuses. 
Visceral afferent (sensory) fibres follow the parasympathetic supply.
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17
Q

lymph drainage of rectum

A

pararectal lymph nodes, which drain into the inferior mesenteric nodes.

lymph from the lower aspect of the rectum drains directly into the internal iliac lymph nodes.

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18
Q

lower dilated portion of rectum

A

rectal ampulla

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19
Q

final segment of the gastrointestinal tract.

A

anal canal

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20
Q

fx of anal canal

A

important role in defecation and maintaining faecal continence.

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21
Q

this muscle surrounds the upper 2/3 of the anal canal. It is formed from a thickening of the involuntary circular smooth muscle in the bowel wall.

A

voluntary muscle that surrounds the lower 2/3 of the anal canal (and so overlaps with the internal sphincter). It blends superiorly with the puborectalis muscle of the pelvic floor.

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22
Q

anal canal is surrounded by these muscles

A

internal anal sphincyer

external anal sphincter

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23
Q

At the junction of the rectum and the anal canal, there is a muscular ring – known as the

A

anorectal ring

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24
Q

formed by the fusion of the internal anal sphincter, external anal sphincter and puborectalis muscle, and is palpable on digital rectal examination.

A

anorectal ring

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25
Q

superior aspect of the anal canal has the same epithelial lining as the rectum,
_____

A

columnar epithelium

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26
Q

in the anal canal, the mucosa is organised into longitudinal folds, known as

A

anal columns

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27
Q

anal columns are joined at their inferior ends by

A

anal valves

28
Q

Above the anal valves are small pouches which are referred to a

A

anal sinuses

29
Q

The anal valves collectively form an irregular circle – known as the

A

pectinate line / dentate line

30
Q

This line divides the anal canal into upper and lower parts, which differ in both structure and neurovascular supply.

A

pectinate line

31
Q

rectum

length

A

5 inches

32
Q

anal canal

length

A

4 cm long

33
Q

anal canal begins at level of this m. up to the anus

A

puborectalis m.

34
Q

Above the pectinate line – derived from the

A

embryonic hindgut

35
Q

Below the pectinate line – derived from the

A

ectoderm of the proctodeum

36
Q

Inferior to the pectinate line, the anal canal is lined by

A

non-keratinised stratified squamous epithelium (known as the anal pecten

37
Q

Inferior to the pectinate line, the anal canal is lined by non-keratinised stratified squamous epithelium (known as the anal pecten). It is a pale and smooth surface, which transitions at the level of the ____ to true skin (keratinised stratified squamous).

A

intersphincteric groove

38
Q

above the pectinate line

arterial supply

A

Superior rectal artery (branch of inferior mesenteric artery)

Anastomosing branches from the middle rectal artery.

39
Q

above the pectinate line

venous drainage

A

Superior rectal vein, which empties into the inferior mesenteric vein (portal venous system).

40
Q

above the pectinate line

Nerve Supply

A

Visceral innervation via the inferior hypogastric plexus.

Sensitive to stretch

41
Q

Lymphatics

above the pectinate line

A

internal iliac LN

42
Q

below the pectinate line

arterial supply

A

Inferior rectal artery (branch of the internal pudendal artery)

Anastomosing branches from the middle rectal artery.

43
Q

below the pectinate line

Venous Drainage

A

Inferior rectal vein, which empties into the internal pudendal vein (systemic venous system).

44
Q

below the pectinate line

nerve supply

A

Somatic innervation via the inferior rectal nerves (branches of the pudendal nerve)
Sensitive to pain, temperature, touch and pressure.

45
Q

below the pectinate line

lymphatics

A

Superficial inguinal lymph nodes

46
Q

vascular cushions found within the anal canal of healthy individuals, which help with the maintenance faecal continence.

A

hemorrhoids

47
Q

Pathological haemorrhoids are observed in people who

A

suffer from constipation, prolonged straining when defecating, or raised intra-abdominal pressure (e.g pregnancy, ascites).

48
Q

Upon examination of the anal canal (with the patient in the lithotomy position), the haemorrhoids are typically located at the_____ o’clock positions.

A

3, 7 and 11

49
Q

upper part of the anal canal is sensitive to

A

stretch

50
Q

lower part of the anal canal is sensitive to

A

pain
temp
touch
pressure

51
Q

painless protrusions of the anal canal covered by mucosa

contain dilated veins of the internal rectal venous plexus

A

internal hemorrhoids

52
Q

painful enlargements covered by the skin that contain dilated veins of the external rectal venous plexus

A

external hemorrhoids

53
Q

results from the failure of peristalsis in the aganglionic segment

A

hirschsprung disease/ congenital megacolon

54
Q

ileal diverticulum

A

meckel diverticulum

55
Q

persistence of remnant vitelline duct forming an outpouching located on antemesenteric border of ileum

A

meckel diverticulum

56
Q

pain from foregut is perceived in

A

epigastric region

57
Q

pain from midgut is perceived in

A

periumbilical

58
Q

pain from hindgut is perceived in

A

hypogastric region

59
Q

Rule of nerve supply

Foregut

A

P: Vagus
S: lower thoracic splanchnic nerves T5-T9

60
Q

Rule of nerve supply

Midgut

A

P: Vagus n.
S: lower thoracic splanchnic nerves T5-T12

61
Q

Rule of nerve supply

Hindgut

A

P: pelvic splanchnic nerves S2-S4
S: lower thoracic and lumbar splanchnic nerves T11-L2

62
Q

preaortic lymphatics referred to as

A

celiac
superior mesenteric
inferior mesenteric LN

63
Q

lymphatics below the pectinate line (perineum, genitalia, anal canal)

A

superficial inguinal LN

64
Q

lymphatics of the anal canal above the pectinate line, bladder, uterus, vagina, prostate

A

internal iliac LN

65
Q

is a disorder affecting either the lumbar or sacral plexus of nerves. They are rare syndromes, caused by damage to the nerve bundles.

A

lumbosacral plexopathy

66
Q

main causes of lumbosacral plexopathy

A

diabetic amyotrophy (aka lumbosacral radioplexus neurophagy)

Idiopathic plexopathy -lumbosacral equivalent of Parsonage-Turner syndrome (which affects the brachial plexus).

tumors and other local invasions

67
Q

tx for DM cause of lumbosacral plexopathy

A

high dose corticosteroids

Anatomy Topnotch (26 decks)

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