Download MBBS (Bachelor of Medicine and Bachelor of Surgery) Latest Rectum and Anal Canal Lecture PPT
RECTUM & ANAL CANAL
Anal triangle(Posterior Perineum)
Posterior part of
perineum
Boundaries:
Anteriorly: imaginary
line joining two ischial
Tuberosities.
POSTEROLATERALLY:
sacrotuberous
ligament
Ischioanal (ischiorectal) fossa:
A perineal space on both side of anal canal.
Wedge shaped with apex directed upwards.
Lateral wall vertical and medial wall sloping downward and medially.
Fat filled: allows expansion of rectum and anal canal during
defecation.
Ischioanal (ischiorectal) fossa:
Measurements:
Vertical- 5cm
Anteroposterior- 5cm
Transverse- 2.5cm
Ischioanal (ischiorectal) fossa:
Boundaries
Laterally : obturator internus
and its fascia & ischial
tuberosity
Medially: levator ani covered by
anal fascia & external anal
sphincter
Anteriorly: superficial and deep
transverse perineal muscles.
Posteriorly: sacrotuberous
ligament covered by Gluteus
Maximus
Apex: fusion of obturator and
anal fascia
Base: skin and superficial fascia
Ischioanal (ischiorectal) fossa:
Lunate fascia:
Arched fascia in ischiorectal
fossa.
Starts from the periosteum
of ischial tuberosity makes
medial wall of pudendal
canal, lines obturator fascia
goes towards apex and
lines anal fascia blends with
it at the level of white line of
Hilton.
Summit of this facia called
tegmentum.
Pudendal or Alcock's canal:
Fascial tunnel in lateral
wall of ischiorectal fossa
2.5cm above ischial
tuberosity.
Formed either by
splitting of obturator
fascia or by separation
between lunate and
obturator fascia or by
splitting of perianal
fascia.
Pudendal or Alcock's canal:
?Extends from lesser sciatic foramen to posterior limit of deep perineal
space.
?contents: internal pudendal vessels & pudendal nerve
and its 2 branches- dorsal nerve of penis/clitoris and
perineal nerve.
Parts of ischiorectal fossa:
Suprategmental:
above lunate fascia
contains loose fat.
Ischiorectal space
proper: between
lunate and perianal
fascia. Contain fat
with fibrous tissue.
Perianal space:
between perianal
fascia and skin.
Contains loculated fat
in tight fibroelastic
compartments.
Contents
?Internal pudendal vessels and pudendal
nerve
?Inferior rectal vessels and nerve
?Posterior scrotal/labial vessels and nerves
?Perineal branch of 4th and perforating
branch of 2nd and 3rd sacral nerve.
?Fat pad.
APPLIED ANATOMY
Ischiorectal abscess:
loose fat so an abscess in
this region may grow to a
large size before
producing pain.
Perianal abscess: fat is in
tight compartments so
the abscess is very
painful due to tension
caused by building pus.
Abscess bursting in the
anal canal may produce
fistula in ano.
APPLIED ANATOMY
Pudendal block: for perineal anesthesia.
Generally done in 2nd stage of labour to perform or repair
episiotomy.
Transvaginal and Transperineal approach.
RECTUM
LARGE INTESTINE
LARGE INTESTINE
3 unique features:
? Teniae coli ? Three bands of longitudinal smooth muscle.
?Haustrations ? Pocket like sacs caused by tone of teniae coli.
?Epiploic appendages ? Fat-filled pouches of visceral
peritoneum.
? Subdivided into Caecum, Appendix, Colon, Rectum &
?Anal canal
Rectum
? Introduction
? Extent
? Course &
directions
? Relations
? Mucosal folds
? Blood & nerve
supply
? Supports
? Applied
anatomy
INTRODUCTION
Terminal part of large intestine before anal canal.
? Cardinal features of large intestine ? absent
?Length ? 12 cm
?Diameter ? upper part 4 cm, lower part dilated as rectal
ampulla
? Curved in both sagittal and coronal planes
? Function ? temporary storage of fecal matter;distension
causes desire to defecate
Extent
?Begins at S3, lower
end of sigmoid
mesocolon ?
recto-sigmoid
junction.
?Ends slightly below
and 2- 3 cm in front
of tip of coccyx ?
anorectal junction.
? Males ? at level of
apex of prostate.
Course and directions
? Beginning and end lie in median plane
? 2 AP curvatures
? Sacral flexure ? follows curvature of sacrum and coccyx
? Perineal flexure ? backward bend in anorectal junction
? 3 lateral curvatures
? Upper ? convex to right
? Middle ? convex to left
? most prominent
? Lower ? convex to right
Peritoneal relations
? Upper 1/3 ? in front and sides
? Middle 1/3 ? only in front
? Lower 1/3 ? devoid of peritoneum
? Dilated to form ampulla
? Below rectovesical pouch in males
? Below recto uterine pouch in females
Visceral relations
? Anteriorly - in males
? Upper 2/3 ?
rectovesical
pouch with coils of
Intestine
? Lower 1/3 ? base of
urinary bladder, ureters,
seminal vesicle, vas and
prostate
Visceral relations
? Anteriorly in females
? Upper 2/3 ? recto- uterine pouch with coils of intestine and sigmoid
colon, pouch separates the rectum from uterus and upper part of vagina
? Lower 1/3 ? lower part of vagina
Visceral relations
? Posterior in both sexes.
? Lower 3 sacrum, coccyx and anococcygeal ligament
? Piriformis, coccugeus and levator ani
? Median sacral, sup rectal and lower lat sacral vessels
? Sympathetic chain with ganglion impar, ant primary rami of S3-5, Co1,
and pelvic splanchnic nerves
? Lymph nodes, lymphatics and fat
POST. RELATIONS
Mucosal folds
? 2 types of folds
? Longitudinal ? temporary, in lower part, disappear on distension
? Transverse / Houston's valves ? permanent
INTERIOR OF RECTUM: MUCOSAL
FOLDS
TRANSVERSE MUCOSAL FOLDS
Blood supply
Venous drainage
Lymphatic drainage
? Upper ? - sup
rectal vessels ->
para rectal &
sigmoid nodes ->
inf mesenteric
nodes
? Lower ? - middle
rectal vessels ->
internal iliac nodes
Nerve supply
? Sympathetic ? L 1-2
? Parasympathetic ? S 2-4
? Distension ? Parasympathetic
? Pain - both
Supports
? Pelvic floor by levator ani
? Waldeyer's fascia ? lower part of rectal ampulla to sacrum,
contain sup rectal vessels and Lymphatics
? Lateral ligaments ? contain middle rectal vessels, nerves
? Rectovesical pouch
? Pelvic peritoneum
? Perineal body
APPLIED ANATOMY
?PR EXAM
? PROCTOSCOPY
? RADIOLOGICAL STUDIES
? PROLAPSE AND
INTUSUCEPTION
? POLYP
? CARCINOMA
ANAL CANAL
INTRODUCTION
?Terminal part of alimentary
tract,begins at ano-rectal junction.
?Rectal ampulla suddenly narrows at
ano-rectal junction 2-3 cms infront
and slightly below tip of coccyx.
?From ano-rectal junction canal
passes downwards & backwards
through Pelvic diaphragm.
?Opens at anal orifice situated in the
cleft between buttocks 4 cms below
& in front of tip of coccyx.
Ano-rectal junction in male
corresponds to apex of prostate
4 cms in front of tip of coccyx
Features
Anterior wall shorter than posterior wall
Surrounded by sphincter ani muscles
Canal closed except during defaecation
Measurements
Length (adult) 3.8 cms
Breadth when empty
lateral walls approximated
(antero-posterior slit)
RELATIONS
In front:
1. Perineal body
2. In male ? bulb of penis & spongy
urethra
In female ? Lower part of post. wall
of vagina
Behind:
Ano-coccygeal raphe
Fibro-fatty tissue bet' peri-anal skin
& raphe
On each side:
Ischio-rectal fossa and
its contents
INTERIOR OF ANAL CANAL
Divided by pectineal line &
Hilton's line into 3 areas
1. Upper (15 mm)
2. Intermediate (15 mm)
3. Lower (8 mm)
(Anal verge)
FEATURES IN THE UPPER PART OF ANAL CANAL
1. Anal columns (columns of Morgagni):
These are permanent longitudinal mucous
folds numbering 6 to 10. They contain
radicles of the superior rectal vein.
2. Anal valves (valves of Morgagni): These
are crescentic folds ofmucousmembrane
which connect the lower
ends of adjacent anal columns. The free
margins of thesevalves are directed upward.
The position of these valves is indicated by
the wavy pectinate line (also calleddentate
line).
3. Anal sinuses: These are vertical recesses
between the anal columns and above the anal
valves. The ducts of tubularanal glands
present in the submucosa open in the floor
of anal sinuses.
FEATURES IN THE LOWER PART OF ANAL CANAL
(a) Upper region (often called pecten): It is
15 mm long and extends from the pectinate
line to Hilton's line. It is lined by the non-
keratinized stratified squamous epithelium.
The mucous lining in this region appears
bluish in colour due to underlying dense
venous plexus and is adherent to the
underlying structures.
(b) Lower region of lower anal canal: It is
about 8 mm in extent and lined by the true
skin containing sweat and sebaceous gland.
It shows pigmentation. In adult males,
coarse hairs are often found around the anal
orifice.
PECTINATE LINE
?Muco-cutaneous junction of
anal canal
?Corresponds with position of
anal valves
?Situated at the middle of
internal sphincter
?Divides anal canal into upper
and lower areas (proctodeum)
which are different in
development, blood supply,
lymphdrainage and in nerve
supply
HILTON'S LINE
It is a color contrast bet'
bluish pink area above and
black skin below
The line is represented by
inter-sphincteric groove at
the lower end of the internal
sphincter
Indicates lower end of
internal sphincter
SPHINCTERS OF THE ANAL CANAL
Two ? Internal & external, surround the anal canal.
SPHINCTER ANI INTERNUS
Involuntary sphincter,Thickening of circular muscle of lower part of rectum
Surrounds upper 3/4th of anal canal
Lower end corresponds with Hilton's line
Middle corresponds with pectinate line
Internally the sphin. Is separated from mucous membrane by internal venous plexus
Externally separated from ext. sphin.Muscle by Conjoint sheath derived from levator
ani and longitudinal muscles of rectum
SPHINCTER ANI EXTERNUS
Voluntary sphincter
Surrounds entire length of anal canal
Consists of 3 parts ? Subcuatneous,Superficial & Deep
Nerve Supply of Sphincter
1. The internal sphincter is made up of smooth muscle and
supplied by the autonomic nerve fibres (sympathetic and
parasympathetic), hence it is involuntary.
2. The external anal sphincter is made up of striated muscle
and hence, supplied by the somatic nerve--inferior rectal
nerve and perineal branch of 4th sacral nerve. It is
therefore under voluntary control.
CONJOINT FIBRO ? ELASTIC SHEATH
Formed by longitudinal muscle of rectum blending at ano-
rectal Junction with puborectalis part of leavtor ani
BLOOD SUPPLY
VENOUS DRAINAGE
LYMPHATIC DRAINAGE
APPLIED ANATOMY
Fibrous tracts communicating with two
surfaces Ano-rectal mucosa and skin
Normal Veins Internal & external haemorrhoids
Sentinal pile is a tag formed
by a ruptured anal valve
PR - Per rectal examination
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This post was last modified on 30 November 2021