10. Rectum and Anus

Question 1

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

Answer 1

rectum

Question 2

The rectum begins at the level of the

Answer 2

S3

Question 3

How is Rectum

macroscopically distinct from the colon

Answer 3

1. absence of taenia coli
2. absence of haustra
3. absence of omental appendices

Question 4

course of the rectum is marked by two major flexures:

Answer 4

1. sacral flexure

2. anorectal flexure

Question 5

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

Answer 5

superior,
intermediate,
inferior

Question 6

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

Answer 6

sacral flexures

Question 7

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

Answer 7

transverse folds of the internal rectum wall.

Question 8

final segment of the rectum

Answer 8

ampulla

Question 9

relaxes to accumulate and temporarily store faeces until defecation occurs.

Answer 9

ampulla

Question 10

peritoneum covering of the rectum

Answer 10

• 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.

Question 11

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

Answer 11

rectovesical pouch

Question 12

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

Answer 12

rectouterine pouch (pouch of Douglas)

Question 13

rectum receives arterial supply through three main arteries:

Answer 13

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.

Question 14

venous drainage of the recum is via

Answer 14

superior r.v -> portal venous system

middle and inferior rectal veins -> systemic venous system

Question 15

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

Answer 15

portocaval anastomosis.

Question 16

innervation of the rectum

Answer 16

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.

Question 17

lymph drainage of rectum

Answer 17

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.

Question 18

lower dilated portion of rectum

Answer 18

rectal ampulla

Question 19

final segment of the gastrointestinal tract.

Answer 19

anal canal

Question 20

fx of anal canal

Answer 20

important role in defecation and maintaining faecal continence.

Question 21

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.

Answer 21

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.

Question 22

anal canal is surrounded by these muscles

Answer 22

internal anal sphincyer

external anal sphincter

Question 23

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

Answer 23

anorectal ring

Question 24

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

Answer 24

anorectal ring

Question 25

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

Answer 25

columnar epithelium

Question 26

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

Answer 26

anal columns

Question 27

anal columns are joined at their inferior ends by

Answer 27

anal valves

Question 28

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

Answer 28

anal sinuses

Question 29

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

Answer 29

pectinate line / dentate line

Question 30

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

Answer 30

pectinate line

Question 31

rectum | length

Answer 31

5 inches

Question 32

anal canal | length

Answer 32

4 cm long

Question 33

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

Answer 33

puborectalis m.

Question 34

Above the pectinate line – derived from the

Answer 34

embryonic hindgut

Question 35

Below the pectinate line – derived from the

Answer 35

ectoderm of the proctodeum

Question 36

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

Answer 36

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

Question 37

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).

Answer 37

intersphincteric groove

Question 38

above the pectinate line | arterial supply

Answer 38

Superior rectal artery (branch of inferior mesenteric artery) Anastomosing branches from the middle rectal artery.

Question 39

above the pectinate line | venous drainage

Answer 39

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

Question 40

above the pectinate line | Nerve Supply

Answer 40

Visceral innervation via the inferior hypogastric plexus. | Sensitive to stretch

Question 41

Lymphatics above the pectinate line

Answer 41

internal iliac LN

Question 42

below the pectinate line arterial supply

Answer 42

Inferior rectal artery (branch of the internal pudendal artery) Anastomosing branches from the middle rectal artery.

Question 43

below the pectinate line Venous Drainage

Answer 43

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

Question 44

below the pectinate line | nerve supply

Answer 44

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

Question 45

below the pectinate line | lymphatics

Answer 45

Superficial inguinal lymph nodes

Question 46

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

Answer 46

hemorrhoids

Question 47

Pathological haemorrhoids are observed in people who

Answer 47

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

Question 48

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

Answer 48

3, 7 and 11

Question 49

upper part of the anal canal is sensitive to

Answer 49

stretch

Question 50

lower part of the anal canal is sensitive to

Answer 50

pain temp touch pressure

Question 51

painless protrusions of the anal canal covered by mucosa | contain dilated veins of the internal rectal venous plexus

Answer 51

internal hemorrhoids

Question 52

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

Answer 52

external hemorrhoids

Question 53

results from the failure of peristalsis in the aganglionic segment

Answer 53

hirschsprung disease/ congenital megacolon

Question 54

ileal diverticulum

Answer 54

meckel diverticulum

Question 55

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

Answer 55

meckel diverticulum

Question 56

pain from foregut is perceived in

Answer 56

epigastric region

Question 57

pain from midgut is perceived in

Answer 57

periumbilical

Question 58

pain from hindgut is perceived in

Answer 58

hypogastric region

Question 59

Rule of nerve supply | Foregut

Answer 59

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

Question 60

Rule of nerve supply | Midgut

Answer 60

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

Question 61

Rule of nerve supply | Hindgut

Answer 61

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

Question 62

preaortic lymphatics referred to as

Answer 62

celiac superior mesenteric inferior mesenteric LN

Question 63

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

Answer 63

superficial inguinal LN

Question 64

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

Answer 64

internal iliac LN

Question 65

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

Answer 65

lumbosacral plexopathy

Question 66

main causes of lumbosacral plexopathy

Answer 66

diabetic amyotrophy (aka lumbosacral radioplexus neurophagy) Idiopathic plexopathy  -lumbosacral equivalent of Parsonage-Turner syndrome (which affects the brachial plexus). tumors and other local invasions

Question 67

tx for DM cause of lumbosacral plexopathy

Answer 67

high dose corticosteroids