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The Anal Canal Flashcards

1
Q

The anal canal is…

A

…the final (terminal) segment of the gastrointestinal tract, extending between the rectum and the anus.

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2
Q

The anal canal extends between the…

A

The rectum and anus

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3
Q

The anal canal has an important role in…

A

…defecation and maintaining faecal continence

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4
Q

The anal canal connects with the rectum at…

A

…the point where it passes through a muscular pelvic diaphragm

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5
Q

The Anal Canal is distinguished from the rectum because of…

A

…the transition of its internal surface from a mucous membrane layer (endodermal) to one of skin-like tissue (ectodermal).

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6
Q

The anal canal is situated…

A

…below the level of the pelvic diaphragm. It lies in the anal triangle of perineum, in between the right and left ischioanal fossae, which allow its expansion during passage of the faeces.

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7
Q

The sacculations and taeniae are absent in the anal canal. True or false?

A

True

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8
Q

Dimension of the anal canal

A

The anal canal is 2.5 to 4 cm (1 to 1.5 inches) in length

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9
Q

Diameter of the anal canal in relation to rectum

A

Its diameter is narrower than that of the rectum to which it connects.

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10
Q

The anal canal starts from and ends at…

A

the anorectal junction to the anus.

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11
Q

Direction of the anal canal

A

From the ano-rectal junction, it passes downwards & backwards through the pelvic diaphragm

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12
Q

The anal canal is surrounded by…

A

…inner involuntary sphincters which keep the lumen closed in the form of an anteroposterior slit.

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13
Q

The anorectal junction is marked by…

A

…the forward convexity of the perineal flexure of the rectum

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14
Q

The anorectal junction lies…

A

…2-3cm in front of and slightly below the tip of the coccyx

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15
Q

What is the anorectal angle at the anorectal junction?

A

80 degrees

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16
Q

The anal canal opens at…

A

…the anal orifice situated in the intergluteal cleft 4 cm below & in front of tip of coccyx.

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17
Q

The Ano-rectal junction in males

corresponds to…

A

…the apex of prostate

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18
Q

The canal is divided into…

A

…three areas:

  • The upper longitudinal folds - anal column
  • The lower portion with sphincters
  • The anal orifice
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19
Q

The interior of the anal canal is divided by ____ into ____

A

…by pectinate & Hilton’s line into 3 areas.

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20
Q

Lengths of the divisions of the anal canal

A

Upper part - 15 mm long
Middle part - 15 mm long
Lower part - 8mm long

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21
Q

Each part of the anal canal is lined by…

A

…a characteristic epithelium and reacts differently to various diseases of this regions

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22
Q

The upper part of the anal canal is lined by…

A

…mucous membrane, and is of endodermal origin.

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23
Q

The mucous membrane is made up of ____ folds called… shows:

A

6 to 10 vertical folds; called the anal columns of Morgagni

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24
Q

The lower ends of the anal columns are united to each other by…

A

…short transverse folds of mucous membrane called the anal valves.

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25
Above each anal valve, there is...
...a depression in mucosa which is called the anal sinus.
26
The anal valves together form a...
...transverse line called the pectinate line, that runs all round the anal canal.
27
The pectinate line is situated...
...opposite the middle of internal anal sphincter, the junction of ectodermal and endodermal parts.
28
Occasionally, the anal valves show...
...epithelial projections called anal papillae, which are remnants of the embryonic anal membrane
29
The middle layer of the anal canal is also lined by...
...a mucous membrane
30
What is the colour of the mucosa of the middle layer of the anal canal?
It has a bluish appearance because of a dense venous plexus that lies between it and the muscle coat.
31
The mucosa in the upper region is less mobile than in the middle part of the anal canal. True or false?
False. It is more mobile.
32
The less mobile middle region of the anal canal is referred to as the...
...pecten or transitional zone.
33
Hilton’s line is situated at...
...the level of the interval between the subcutaneous part of the external anal sphincter and the lower border of internal anal sphincter.
34
Hilton’s line marks...
...the lower limit of pecten or stratified squamous epithelium which is thin, pale and glossy and is devoid of sweat glands
35
What is the colour of the lower limit of the pecten?
It is usually whitish and so is referred to as the white base of Hilton
36
The lower cutaneous part of the anal canal is lined by...
...true skin containing sweat and sebaceous glands.
37
The epithelium of the lower part of the anal canal resembles...
...that of the true skin in which sebaceous and sweat glands are present.
38
In terms of musculature, the anal canal is surrounded by...
...internal and external anal sphincters, which play a crucial role in the maintenance of faecal continence
39
Limit of the internal anal sphincter
It surrounds the upper 2/3 of the anal canal
40
The internal anal sphincter is formed from...
...a thickening of the involuntary circular smooth muscle in the bowel wall.
41
Limit of the external anal sphincter
It surrounds the lower 2/3 of the anal canal.
42
The external anal sphincter is a voluntary muscle. True or false?
True
43
The external anal sphincter blends...
...superiorly with the puborectalis muscle of the pelvic floor.
44
Anterior anatomical relations of the anal canal in males
- Perineal body - Membranous urethra - Bulb of penis
45
Anterior anatomical relations of the anal canal in females
- Perineal body | Lower end of the vagina. Posteriorly Anococcygeal ligament. Tip of the coccyx. Laterally: Ischioanal fossae
46
Which anterior anatomical relations of the anal canal is/are present in both males and females?
Perineal body
47
Posterior anatomical relations of the anal canal
Anococcygeal ligament. Tip of the coccyx. Laterally: Ischioanal fossae
48
The anorectal ring is a...
...muscular ring present at the anorectal junction.
49
The anorectal ring is formed by...
...the fusion of the puborectalis, uppermost fibres of external sphincter and the internal sphincter
50
The anorectal ring is easily felt by a finger in the anal canal. True or false?
True
51
Surgical division of this ring results in...
...rectal incontinence.
52
Where is the anorectal ring less marked anteriorly?
Where the fibers of the puborectalis are absent.
53
The surgical anal canal extends from...
...From the anorectal ring to the anal verge
54
The anatomical anal canal extends from...
Pectinate/dentate line to the anal verge
55
The ischioanal space or fossa lies...
...on each side of the anal canal.
56
The perianal space surrounds...
...the anal canal below the white line.
57
Contents of the perianal space
- lower fibers of the external sphincter - the external rectal venous plexus - terminal branches of the inferior rectal vessels and nerves.
58
Surgical spaces related to the anal canal
- The ischioanal space/fossa | - The perianal space
59
Pus in the perianal space spreads to the ischioanal space. True or false?
False, it tends to spread to the anal canal at the white line or to the surface of the perineal skin rather than to the ischioanal space.
60
The submucous space of the anal canal lies...
...above the white line between the mucous membrane and the internal sphincter.
61
Contents of the sub-mucous space of the anal canal
It contains the internal rectal venous plexus and lymphatics.
62
Embryonic origins of the anal canal above snd below the pectinate line.
Above – the embryonic hindgut | Below – the ectoderm of the proctodeum
63
Blood supply above the pectinate line is...
Superior rectal artery (branch of inferior mesenteric artery)
64
Blood supply below the pectinate line is...
Inferior rectal artery (branch of the internal pudendal artery)
65
The internal rectal venous plexus or haemorrhoidal plexus lies in
the submucosa of the anal canal.
66
The internal rectal venous plexus (upper part) drains mainly into
the superior rectal vein
67
The internal rectal venous plexus communicates freely with the external plexus and thus with the middle and inferior rectal veins. True or false?
True
68
The superior rectal vein continues as...
...the mesenteric vein
69
The lower part of the internal plexus is drained by...
...the inferior rectal vein into the internal pudendal vein
70
The middle part of the internal venous plexus is drained by...
...the middle rectal vein into the internal iliac vein
71
Haemorrhoids are...
...vascular cushions found within the anal canal of healthy individuals, which help with the maintenance faecal continence.
72
Swollen and distended haemorrhoids are referred to as...
...pathological haemorrhoids.
73
Pathological haemorrhoids are observed in people who suffer from...
- constipation - prolonged straining when defecating - raised intra-abdominal pressure (e.g pregnancy, ascites).
74
Haemorrhoids are typically located at what positions?
The 3, 7 and 11 o’clock positions.
75
Effects of haemorrhoids
Bleeding and pain on defecation
76
Treatment of haemorrhoids
It can be managed conservatively or surgically.
77
Causes of anal haemorrhoids
Excessive straining during defecation may rupture one of the radially arranged anal veins, forming a subcutaneous perianal haematoma known as external piles.
78
Lymph vessels from the part above and below the pectinate line drain into...
Above - the internal iliac nodes | Below - the medial group of the superficial inguinal nodes.
79
Nerve supply of the anal canal
Above the pectinate line - sympathetic inferior hypogastric plexus; L1, L2) and parasympathetic pelvic splanchnic, S2, S3, S4). Below the pectinate line - somatic (inferior rectal, S2, S3, S4) nerves.
80
The anal canal is supplied by both autonomic or somatic nerves. True or false?
True
81
Anorectal diseases
Hemorrhoids Ischiorectal Abscess Fistula in ani Fissure in ano Warts Fournier’s gangrene Foreign Body
82
Which degree of haemorrhoids bulge into anal canal, prolapse beyond dentate line?
First degree
83
Which degree of haemorrhoids prolapse through anus, reduce spontaneously?
Second degree
84
What degree of haemorrhoids require manual reduction?
Third degree
85
What degree of haemorrhoids cannot be reduced and are prone to strangulation?
Fourth degree
86
What is an anal fistula?
An abnormal communication between the anal canal & skin
87
What is the association between anal abscess and fistula?
Approx. 50% of abscesses occur secondary to anal fistula. Abscess is the acute sign.
88
A fistula-in-ano is...
...an abnormal hollow tract or cavity that is lined with granulation tissue and that connects a primary opening inside the anal canal to a secondary opening in the perianal skin
89
Secondary tracts in fistula-in-ano may be multiple and can extend from the same primary opening. True or false?
True
90
Which processes are similar to fistula-in-ano but don’t communicate with the anal canal?
Hidradenitis suppurativa Infected inclusion cysts Pilonidal disease Bartholin gland abscess in females
91
Most fistulas are thought to arise as a result of...
...cryptoglandular infection with resultant perirectal abscess.
92
Which one is chronic/acute? Fistula or abscess?
The abscess is the acute inflammatory event, whereas the fistula is the chronic process.
93
Difference between internal and external haemorrhoids
- Internal haemorrhoids, originating in the rectum | - External haemorrhoids, originating in the anus
94
Name the venous plexus which is enlarged to internal haemorrhoids.
Rectal venous plexus
95
Congenital anomaly of the anal canal
Imperforate anus, resulting from the failure of the nerves responsible for excretion here to develop properly

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