Clinical anatomy of faecal continence

Question 1

what are the functions of the rectum, anal canal and anus?

Answer 1

= to excrete stool

Question 2

what is the holding area of stored faeces called before it is fefecated?

Answer 2

the rectum

Question 3

what senses ‘fullness’ of the rectum?

what responds to the fullness?

Answer 3

= normal visceral afferents nerve fibres

Response
= functioning muscle sphincters around the distal end of the GI tract

Question 4

what do the sphincters do to allow defeceation?

Answer 4

= to allow contraction, preventing defeceation and to relax allowing defeceation

Question 5

what controls the appropriate time to defecate?

Answer 5

= normal cerebral function

Question 6

what can all of the normal visceral afferent nerve fibres, normal cerebral function e.t.c be affected by?

Answer 6

neurological pathology

e.g. stroke, dementia, stroke, MS, trauma

Question 7

how else can faecal continence be affected? (3)

Answer 7

1) by medications
2) by natural age related degeneration of nerve innervation of muscle
3) by consistency of stool

Question 8

where dos the pelvic cavity lie?

Answer 8

= bony pelvis

Question 9

what is the pelvic cavity continuous with?

Answer 9

abdominal cavity above

Question 10

what does the pelvic cavity lie between?

Answer 10

= pelvic inlet and pelvic floor

Question 11

what does the pelvic cavity contain?

Answer 11

= pelvic organs and supporting tissue

Question 12

where is the rectum located?

Answer 12

= within pelvic cavity

Question 13

what does openings in the pelvic floor permit?

Answer 13

= permits the distal parts of alimentary, renal and reproductive tracts to pass from pelvic cavity into the perineum

Question 14

what must pass trough the pelvic floor?

Answer 14

= rectum/anal canal

Question 15

when does the sigmoidal colon become rectum?

Answer 15

= anterior to S3

“recto-sigmoidal junctions:

Question 16

when does the rectum become the anal canal?

Answer 16

= anterior to the tip of coccyx just prior to passing through the elevator ani muscle

Question 17

describe the anus.

Answer 17

= distal end of the anal canal and is the orifice through with faeces pass

Question 18

where is the rectum, anal canal and anus located?

Answer 18

Rectum
= pelvis

Anal canal and anus
= perineum

Question 19

where does the rectal ampulla lie?

Answer 19

= immediately superior to elevator ani muscle

Question 20

why do the rectal walls relax?

Answer 20

= two accommodate faecal material

Question 21

why are functioning muscles and muscle sphincters required?

Answer 21

= to hold faeces in the ampulla until appropriate to defecate

Question 22

what does the peritoneum cover?

Answer 22

= the superior rectum

Question 23

where does the Rectouterine/rectovesical pouch lie?

Answer 23

= anterior to superior rectum

Question 24

describe the location of the rectum in male and female anatomy?

Answer 24

Male
= prostate gland lies anterior to inferior rectum

female
= the vagina and cervix lies anterior to inferior/middle rectum

Question 25

what do the levator ani muscles form?

Answer 25

= most of pelvic diaphragm together with fascial coverings Forms - most of floor of pelvis - forms most of roof of perineum

Question 26

what is the levator ani muscles made up of?

Answer 26

= a number of smaller muscles - puborectalis - pubococygeus - iliococcygeus

Question 27

what sort of muscle is levator ani muscles?

Answer 27

= skeletal muscle

Question 28

what do levator ani muscles provide?

Answer 28

= continual support for the pelvis organs - tonically contracted most of the time - reflexively contracts further during increase in intra-abdominal pressure e.g. coughing or sneezing - the muscles relax to allow defecation (& urinnation) to occur

Question 29

what is the levator ani muscles supplied by?

Answer 29

= nerve to levator ani (a branch of the sacral plexus) & pudendal (S2, 3, 4)

Question 30

what does contraction of puborectalis result in?

Answer 30

= decreases anorectal angles, acting like a sphincter

Question 31

what is puborectalis controlled by?

Answer 31

= skeletal muscles; contraction is under voluntary control

Question 32

describe what happens when the rectal ampulla is relaxed and filled with faecees and then voluntary contraction occurs?

Answer 32

= voluntary contraction of this muscle will helps maintain continence

Question 33

describe the location of anal canal and anorectal junction.

Answer 33

anal canal is below the anorectal junction

Question 34

what are the 2 anal sphincters?

Answer 34

1 internal sphincter (smooth muscle) - superior 2/3rds of anal canal - contraction stimulated by sympathetic nerves - contraction is inhibited by parasympathetic nerves - contracted all the time, relaxes reflexively in response to distension of renal ampulla 1 external sphincter (skeletal muscle) - inferior 2/3rds of anal canal - contraction stimulated by pudenal nerves - voluntary contracted in response to renal ampulla distension and internal sphincter relaxation

Question 35

why is the nerve supply fundamental?

Answer 35

= fundamental to dividing which nerve fibre types are carrying out with function

Question 36

what are the structures in pelvis and perineum?

Answer 36

Pelvis; - body cavity - sympathetic, para-sympathetic and visceral afferents Perineum - body wall - somatic motor and somatic sensory

Question 37

where does the sympathetic fibres run from?

Answer 37

T12-L2 - travels from inferior mesenteric ganglia - synapse- then travel via peri-arterial plexuses around branches of IMA = contraction of internal anal sphincter = inhibits peristalsis

Question 38

where do the parasympathetic fibres run from?

Answer 38

S2-S4 - via pelvic splanchnic nerves, synapse in walls of rectum = inhibits internal anal sphincter = stimulates peristalsis

Question 39

describe the visceral afferents and somatic motor?

Answer 39

Viceral afferents; - back to S2-S4 = run with parasympathetics = sense stretch, ischaemia Somatic motor; - from pudendal nerve (S2-S4) and nerve to elevator ani (S3-S4) = contraction of external anal sphincter and puborectalis

Question 40

describe the pudendal nerve?

Answer 40

= branch of sacral plexus - S2, S3, S4 anterior rami = supplies external anal sphincter = exits pelvis via greater sciatic foramen = quickly enters perineum via lesser sciatic foramen - branches to supply structure of perineum

Question 41

what does the tear of perineum result in?

Answer 41

= tear extends posteriorly to involve the external anal sphincter

Question 42

describe what happens during labour?

Answer 42

= branches of pudendal nerve could be stretched - fibres within the pubo-rectalis or external anal sphincter muscle could be torn - results in weakened muscle and lead to faecal in-continence

Question 43

what line is the anal Canal on?

Answer 43

= pectinate line - marks the junction between part of embryo which formed the GI tract (endoderm) and part that formed the skin (endoderm)

Question 44

True or False. | Arterial supply, venous drainage, lymphatic drainage and nerve supply differ above and below pectinate line.

Answer 44

True Superior to line = visceral Inferior to line = pariettal

Question 45

what is above the pectinate line?

Answer 45

Nerve supply = autonomic Arterial supply = from inferior mesenteric artery Venous drainage = to hepatic portal system Lymphatic drainage = inferior mesenteric nodes

Question 46

what is below the pectinate line?

Answer 46

Nerve supply = somatic and pudendal Arterial supply = from internal iliac artery Venous drainage = to systemic venous system Lymphatic drainage = superficial inguinal nodes

Question 47

what are the 4 main groups of lymph nodes gaining the pelvic organs?

Answer 47

1) Internal iliac (draining inferior pelvic structures) 2) External iliac (draining lower limb, and more superior pelvic structures) 3) Common iliac (drain the lymph from the external and internal iliac nodes) 4) Lymph draining through the common iliac nodes then drains to the lumbar nodes

Question 48

what does the inferior mesenteric artery supply and what is the remainder of GI tract supplied by?

Answer 48

= the hindgut organs - hindgut extends to proximal half of the anal canal (the pectinate line) Remainder; = supplied by internal iliac artery - there is a degree of anastomoses between these vessels

Question 49

what drains the hindgut organs?

Answer 49

= inferior mesenteric veins - above pectinate line - portal venous system

Question 50

what vein drains below the pectinate line? (systemic venous system)

Answer 50

= internal iliac vein

Question 51

when do rectal varices from?

Answer 51

= in relation to porttal hypertension - distension of collateral veins between portal and systemic venous system

Question 52

what are haemorrhoids?

Answer 52

= prolapses of rectal venous plexuses - their development is NOT related to portal hypertension - i.e. raised pressure e.g. chronic constipation, straining, pregnancy

Question 53

where does the ischioanal fossa lie?

Answer 53

= on each side of anal canal

Question 54

what is the ischioanal fossa filled with?

Answer 54

= fat and loose connective tissue

Question 55

how do the two ischioanal fossa communicate with each other?

Answer 55

= posteriorly

Question 56

what is an infection within the ischioanal fossa called?

Answer 56

= ischioanal abscess

Question 57

what is proctoscopy, sigmoidoscopy and colonoscopy?

Answer 57

Proctoscopy = viewing interior of rectum Sigmoidoscopy = viewing interior of sigmoid colon Colonoscopy = viewing the interior of colon