Download MBBS Rectum and Anal Canal Lecture PPT

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Posterior part of

perineum

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Boundaries:

Anteriorly: imaginary

line joining two ischial

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Tuberosities.

POSTEROLATERALLY:

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sacrotuberous

ligament

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Ischioanal (ischiorectal) fossa:

A perineal space on both side of anal canal.

Wedge shaped with apex directed upwards.

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Lateral wall vertical and medial wall sloping downward and medially.

Fat filled: allows expansion of rectum and anal canal during

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defecation.


Ischioanal (ischiorectal) fossa:

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Measurements:

Vertical- 5cm

Anteroposterior- 5cm

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Transverse- 2.5cm


Ischioanal (ischiorectal) fossa:

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Boundaries

Laterally : obturator internus

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and its fascia & ischial

tuberosity

Medially: levator ani covered by

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anal fascia & external anal

sphincter

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Anteriorly: superficial and deep

transverse perineal muscles.

Posteriorly: sacrotuberous

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ligament covered by Gluteus

Maximus

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Apex: fusion of obturator and

anal fascia

Base: skin and superficial fascia

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Ischioanal (ischiorectal) fossa:

Lunate fascia:

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Arched fascia in ischiorectal

fossa.

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Starts from the periosteum

of ischial tuberosity makes

medial wall of pudendal

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canal, lines obturator fascia

goes towards apex and

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lines anal fascia blends with

it at the level of white line of

Hilton.

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Summit of this facia called

tegmentum.

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Pudendal or Alcock's canal:

Fascial tunnel in lateral

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wall of ischiorectal fossa

2.5cm above ischial

tuberosity.

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Formed either by

splitting of obturator

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fascia or by separation

between lunate and

obturator fascia or by

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splitting of perianal

fascia.

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Pudendal or Alcock's canal:

?Extends from lesser sciatic foramen to posterior limit of deep perineal

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space.

?contents: internal pudendal vessels & pudendal nerve

and its 2 branches- dorsal nerve of penis/clitoris and

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perineal nerve.


Parts of ischiorectal fossa:

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Suprategmental:

above lunate fascia

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contains loose fat.

Ischiorectal space

proper: between

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lunate and perianal

fascia. Contain fat

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with fibrous tissue.

Perianal space:

between perianal

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fascia and skin.

Contains loculated fat

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in tight fibroelastic

compartments.
Contents

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?Internal pudendal vessels and pudendal

nerve

?Inferior rectal vessels and nerve

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?Posterior scrotal/labial vessels and nerves

?Perineal branch of 4th and perforating

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branch of 2nd and 3rd sacral nerve.

?Fat pad.

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APPLIED ANATOMY

Ischiorectal abscess:

loose fat so an abscess in

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this region may grow to a

large size before

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producing pain.

Perianal abscess: fat is in

tight compartments so

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the abscess is very

painful due to tension

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caused by building pus.

Abscess bursting in the

anal canal may produce

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fistula in ano.


APPLIED ANATOMY

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Pudendal block: for perineal anesthesia.

Generally done in 2nd stage of labour to perform or repair

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episiotomy.

Transvaginal and Transperineal approach.
RECTUM

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LARGE INTESTINE
LARGE INTESTINE

3 unique features:

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? Teniae coli ? Three bands of longitudinal smooth muscle.

?Haustrations ? Pocket like sacs caused by tone of teniae coli.

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?Epiploic appendages ? Fat-filled pouches of visceral

peritoneum.

? Subdivided into Caecum, Appendix, Colon, Rectum &

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?Anal canal


Rectum

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? Introduction

? Extent

? Course &

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directions

? Relations

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? Mucosal folds

? Blood & nerve

supply

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? Supports

? Applied

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anatomy
INTRODUCTION

Terminal part of large intestine before anal canal.

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? Cardinal features of large intestine ? absent

?Length ? 12 cm

?Diameter ? upper part 4 cm, lower part dilated as rectal

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ampulla

? Curved in both sagittal and coronal planes

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? Function ? temporary storage of fecal matter;distension

causes desire to defecate

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Extent

?Begins at S3, lower

end of sigmoid

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mesocolon ?

recto-sigmoid

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junction.

?Ends slightly below

and 2- 3 cm in front

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of tip of coccyx ?

anorectal junction.

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? Males ? at level of

apex of prostate.

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Course and directions

? Beginning and end lie in median plane

? 2 AP curvatures

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? Sacral flexure ? follows curvature of sacrum and coccyx

? Perineal flexure ? backward bend in anorectal junction

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? 3 lateral curvatures

? Upper ? convex to right

? Middle ? convex to left

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? most prominent

? Lower ? convex to right

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Peritoneal relations

? Upper 1/3 ? in front and sides

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? Middle 1/3 ? only in front

? Lower 1/3 ? devoid of peritoneum

? Dilated to form ampulla

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? Below rectovesical pouch in males

? Below recto uterine pouch in females

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Visceral relations

? Anteriorly - in males

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? Upper 2/3 ?

rectovesical

pouch with coils of

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Intestine

? Lower 1/3 ? base of

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urinary bladder, ureters,

seminal vesicle, vas and

prostate

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Visceral relations

? Anteriorly in females

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? Upper 2/3 ? recto- uterine pouch with coils of intestine and sigmoid

colon, pouch separates the rectum from uterus and upper part of vagina

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? Lower 1/3 ? lower part of vagina
Visceral relations

? Posterior in both sexes.

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? Lower 3 sacrum, coccyx and anococcygeal ligament

? Piriformis, coccugeus and levator ani

? Median sacral, sup rectal and lower lat sacral vessels

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? Sympathetic chain with ganglion impar, ant primary rami of S3-5, Co1,

and pelvic splanchnic nerves

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? Lymph nodes, lymphatics and fat


POST. RELATIONS

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Mucosal folds

? 2 types of folds

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? Longitudinal ? temporary, in lower part, disappear on distension

? Transverse / Houston's valves ? permanent

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INTERIOR OF RECTUM: MUCOSAL

FOLDS

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TRANSVERSE MUCOSAL FOLDS


Blood supply

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Venous drainage


Lymphatic drainage

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? Upper ? - sup

rectal vessels ->

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para rectal &

sigmoid nodes ->

inf mesenteric

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nodes

? Lower ? - middle

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rectal vessels ->

internal iliac nodes
Nerve supply

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? Sympathetic ? L 1-2

? Parasympathetic ? S 2-4

? Distension ? Parasympathetic

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? Pain - both
Supports

? Pelvic floor by levator ani

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? Waldeyer's fascia ? lower part of rectal ampulla to sacrum,

contain sup rectal vessels and Lymphatics

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? Lateral ligaments ? contain middle rectal vessels, nerves

? Rectovesical pouch

? Pelvic peritoneum

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? Perineal body
APPLIED ANATOMY

?PR EXAM

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? PROCTOSCOPY

? RADIOLOGICAL STUDIES

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? PROLAPSE AND

INTUSUCEPTION

? POLYP

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? CARCINOMA

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ANAL CANAL


INTRODUCTION

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?Terminal part of alimentary

tract,begins at ano-rectal junction.

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?Rectal ampulla suddenly narrows at

ano-rectal junction 2-3 cms infront

and slightly below tip of coccyx.

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?From ano-rectal junction canal

passes downwards & backwards

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through Pelvic diaphragm.

?Opens at anal orifice situated in the

cleft between buttocks 4 cms below

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& in front of tip of coccyx.

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Ano-rectal junction in male

corresponds to apex of prostate

4 cms in front of tip of coccyx

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Features

Anterior wall shorter than posterior wall

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Surrounded by sphincter ani muscles

Canal closed except during defaecation

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Measurements

Length (adult) 3.8 cms

Breadth when empty

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lateral walls approximated

(antero-posterior slit)

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RELATIONS

In front:

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1. Perineal body

2. In male ? bulb of penis & spongy

urethra

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In female ? Lower part of post. wall

of vagina

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Behind:

Ano-coccygeal raphe

Fibro-fatty tissue bet' peri-anal skin

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& raphe

On each side:

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Ischio-rectal fossa and

its contents

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INTERIOR OF ANAL CANAL

Divided by pectineal line &

Hilton's line into 3 areas

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1. Upper (15 mm)

2. Intermediate (15 mm)

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3. Lower (8 mm)

(Anal verge)

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FEATURES IN THE UPPER PART OF ANAL CANAL

1. Anal columns (columns of Morgagni):

These are permanent longitudinal mucous

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folds numbering 6 to 10. They contain

radicles of the superior rectal vein.

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2. Anal valves (valves of Morgagni): These

are crescentic folds ofmucousmembrane

which connect the lower

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ends of adjacent anal columns. The free

margins of thesevalves are directed upward.

The position of these valves is indicated by

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the wavy pectinate line (also calleddentate

line).

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3. Anal sinuses: These are vertical recesses

between the anal columns and above the anal

valves. The ducts of tubularanal glands

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present in the submucosa open in the floor

of anal sinuses.
FEATURES IN THE LOWER PART OF ANAL CANAL

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(a) Upper region (often called pecten): It is

15 mm long and extends from the pectinate

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line to Hilton's line. It is lined by the non-

keratinized stratified squamous epithelium.

The mucous lining in this region appears

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bluish in colour due to underlying dense

venous plexus and is adherent to the

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underlying structures.

(b) Lower region of lower anal canal: It is

about 8 mm in extent and lined by the true

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skin containing sweat and sebaceous gland.

It shows pigmentation. In adult males,

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coarse hairs are often found around the anal

orifice.

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PECTINATE LINE
?Muco-cutaneous junction of

anal canal

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?Corresponds with position of

anal valves

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?Situated at the middle of

internal sphincter

?Divides anal canal into upper

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and lower areas (proctodeum)

which are different in

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development, blood supply,

lymphdrainage and in nerve

supply

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HILTON'S LINE

It is a color contrast bet'

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bluish pink area above and

black skin below

The line is represented by

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inter-sphincteric groove at

the lower end of the internal

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sphincter

Indicates lower end of

internal sphincter

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SPHINCTERS OF THE ANAL CANAL

Two ? Internal & external, surround the anal canal.

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SPHINCTER ANI INTERNUS

Involuntary sphincter,Thickening of circular muscle of lower part of rectum

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Surrounds upper 3/4th of anal canal

Lower end corresponds with Hilton's line

Middle corresponds with pectinate line

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Internally the sphin. Is separated from mucous membrane by internal venous plexus

Externally separated from ext. sphin.Muscle by Conjoint sheath derived from levator

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ani and longitudinal muscles of rectum


SPHINCTER ANI EXTERNUS

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Voluntary sphincter

Surrounds entire length of anal canal

Consists of 3 parts ? Subcuatneous,Superficial & Deep

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Nerve Supply of Sphincter

1. The internal sphincter is made up of smooth muscle and

supplied by the autonomic nerve fibres (sympathetic and

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parasympathetic), hence it is involuntary.

2. The external anal sphincter is made up of striated muscle

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and hence, supplied by the somatic nerve--inferior rectal

nerve and perineal branch of 4th sacral nerve. It is

therefore under voluntary control.

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CONJOINT FIBRO ? ELASTIC SHEATH

Formed by longitudinal muscle of rectum blending at ano-

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rectal Junction with puborectalis part of leavtor ani


BLOOD SUPPLY

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VENOUS DRAINAGE

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LYMPHATIC DRAINAGE


APPLIED ANATOMY

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Fibrous tracts communicating with two

surfaces Ano-rectal mucosa and skin

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Normal Veins Internal & external haemorrhoids



Sentinal pile is a tag formed

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by a ruptured anal valve


PR - Per rectal examination

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