Anatomy of Rectum

A presentation on the anatomy of the rectum

2. Presentation by
K Hari
Krishnan
IYear MBBS (2008-’09)
Tirunelveli Medical College

3. •Distal part of the
large gut
•The pelvic part of
the alimentary
tract

4. Rectum

5. •Posterior part of
the lesser pelvis
•In front of lower
three pieces of
sacrum and the
coccyx

6. •Begins at the
rectosigmoid
junction
–at level of third
sacral vertebra
•Ends at the
anorectal
junction
–2-3 cm in front of
and a little below
the coccyx

7. •Length
–13 cm (5 in.)
•Diameter
–4 cm (in the upper part)
–Dilated (in the lower part)

9. •Downwards and backwards
•Downwards
•Downwards and forwards

10. •Antero-posterior
flexures (2 in
number)
–Sacral flexure
•Follows the curve of
the sacrum and
coccyx

11. •Antero-posterior flexures
–Perineal flexure / Anorectal flexure
•80°anorectal angle
•In the terminal part of the rectum
•At the anorectal junction
•Here the rectum perforates the pelvic
diaphragm to become the anal canal

13. •Lateral flexures (3 in number) –
correspond to the transverse rectal
folds
•Superior
–Convex to the right
•Intermediate
–Convex to the left
–Most prominent
•Inferior
–Convex to the right

14. •Superior 1/3rd of the rectum
–Covered by peritoneum on the anterior and
lateral surfaces
•Middle 1/3rd of the rectum
–Covered by peritoneum on the anterior
surface
•Inferior 1/3rd of the rectum
–Subperitoneal –Devoid of peritoneum

16. •In males
–Upper 2/3rd
•Rectovesical pouch
•Coils of ileum
•Sigmoid colon
–Lower 1/3rd
•Fundus (base) of the urinary bladder
•Terminal parts of the ureters
•Seminal vesicles
•Ductus deferentes
•Prostate

18. •In females
–Upper 2/3rd
•Rectouterine pouch, which separates the rectum
from the uterus and from the upper part of
vagina
•Coils of ileum
•Sigmoid colon
–Lower 1/3rd
•Lower part of vagina

20. •Bones
–Lower three pieces of sacrum
–Coccyx
•Ligaments
–Anococcygeal ligament
•Muscles
–Piriformis
–Coccygeus
–Levator ani
•Vessels
–Median sacral
–Superior rectal
–Lower lateral sacral
•Nerves
–Sympathetic chain with ganglion impar
–Ventral primary rami of S3, S4, S5, Co1
–Pelvic splanchnic nerves
•Lymph nodes and lymphatics
•Fat

24. •Superior rectal artery
–Direct continuation of Inferior mesenteric artery
–Enters the pelvis by descending in the root of the sigmoid mesocolon
and divides into right and left branches, which pierce the muscular
coat and supply the mucous membrane
–They anastomose with one another and with the middle and inferior
rectal arteries
•Middle rectal artery
–Small branch of anterior division of Internal iliac artery
–Run in the lateral ligaments of the rectum
–Supplies the muscular coat of the lower part of rectum
•Inferior rectal artery
–Branch of Internal pudental artery in the perineum
–Anastomoses with the middle rectal artery at the anorectal junction
•Median sacral artery
–Direct branch from the dorsal surface of Aorta near its inferior end
–Descends in the median plane
–Supplies the posterior wall of the anorectal junction

28. Rectum –Venous drainage
Submucosal plexus
Superior rectal vein
Middle rectal vein
Inferior rectal vein

29. •Submucosal rectal venous plexus
–Surrounds rectum
–Communicates
•vesical venous plexus –males
•uterovaginal venous plexus –females
–2 Parts:
•Internal rectal venous plexus
–Deep to the epithelium of rectum
–Drains into Superior rectal vein
•External rectal venous plexus
–External to the muscular wall of rectum
–Superior portion: drains into Superior rectal vein
–Middle portion: drains into Middle rectal vein
–Inferior portion: drains into Inferior rectal vein

30. •Superior rectal vein
–Formed from Internal rectal venous plexus
–Consists of 6 main tributary veins
–Continues upwards as Inferior mesenteric vein
•Middle rectal vein
–Formed from the middle portion of External rectal venous
plexus
–Pass alongside middle rectal artery
–Drains into the anterior division of Internal iliac vein on the
lateral wall of the pelvis
•Inferior rectal vein
–Formed from the inferior portion of the Inferior rectal vein
–Drains into the Internal pudental vein

32. •Superior half of the rectum
–Pararectal lymph nodes, located directly on
the muscle layer of the rectum
–Inferior mesenteric lymph nodes, via either
the sacral lymph nodes or the nodes along
the superior rectal vessels
•Inferior half of the rectum
–Sacral groupof lymph nodes or Internal iliac
lymph nodes

34. •Sympathetic nerve supply
–L1, L2 fibres
–Through Superior rectaland Inferior hypogastric
plexuses
–Vasoconstrictor
–Inhibitory to musculature of rectum
–Motor to internal sphincter
–Carry sensations of pain
•Parasympathetic nerve supply
–S2, S3, S4 fibres
–Passes via pelvic splanchnicnerves and inferior
hypogastric plexusesto rectal (pelvic) plexus
–Motor to musculature of the rectum
–Inhibitory to internal sphincter
–Carry sensations of pain and distension

38. Mucosal Folds
LongitudinalTransverse

39. Longitudinal folds
•Present in lower
part of the empty
rectum
•Effaced during
distension

40. Transverse folds(Houston’s valves or
plicae transversae recti)
•Marked in rectal distension
•Superior fold
–At beginning of rectum
–Projects from the right or the left wall
•Middle fold
–Above the rectal ampulla
–Projects from the anterior and right walls
–Largest and most constant
•Inferior fold
–About 2.5 cm below the middle fold
–Projects from the left wall
–Variable
•Occasional fourth fold
–About 2.5 cm above the middle fold
–Projects from the left wall

44. •Pelvic Floor
–Levator ani muscles
•Fascia of Waldeyer
–Condensation of pelvic fascia behind rectum
–Lower part of ampulla to Sacrum
–Encloses Superior rectal vessels and lymphatics
•Lateral ligaments of Rectum
•Denonvilliers fascia
•Pelvic peritoneum
•Perineal body

49. •Examination to check for
abnormalities of organs or other
structures in the pelvis and lower
abdomen
•To check for
–growths in or enlargement of
theprostate gland in males. A
tumor in the prostate can
often be felt as a hard lump
–problems in
femalereproductive organs
(uterus and ovaries)
–rectal bleeding or tumors in
the rectum

50. •Proctoscopy -Visual examination of the
rectum and anus
•Visualizing the interior of the rectum and
anal canal
•Helps in revealing ulcers, abnormal
growths and diverticula

51. •Sigmoidoscope
–An endoscope
for viewing the
lumen of the
sigmoid colon

53. •Rectocoele
•Protrusion of the mucous membrane and submucosa of the
rectum outside the anus for approximately 1–4 cm
•Common in
–Children: 1 –3 years
–Elderly people
–Middle-aged women
Rectal Prolapse
PartialComplete

54. •Rectal mucous
membrane and
submucous coat
protrude for a short
distance outside the
anus
•Common in children

55. •Procidentia
•Whole thickness of the
rectal wall protrudes
through the anus
•A sliding hernia through the
pelvic diaphragm
•Common in adults
•Associated with rectal
incontinence

56. Causes
•In infants
–Undeveloped sacral curve
–Reduced resting anal tone –
diminished support to the
mucosal lining of anal canal
•In children
–Diminution of fat in
ischiorectal fossae
•Diarrhoea
•Severe whooping cough
•Sudden loss of weight
–Fibrocystic disease
–Neurological causes
–Mal-development of pelvis

57. Causes
•In adults
–Haemorrhoids
–Torn perineum
–Straining from urethral obstruction
–Following operation for fistula in ano
•In the elderly
–Atony of sphincter mechanism

58. Treatment
•Submucous injections
•Excision of the prolapsed mucosa
•Surgery

59. •Found mainly in
–Rectosigmoid junction
–Ampulla
•Bleeding per rectum
•Initial finding –Lymphatics
around the bowel
•Later –lymph nodes along
superior rectal and middle
rectal arteries
•Venous spread –Superior
rectal vein to portal vein
–Liver –secondary deposits

60. Treatment
•Rectal excision and
total mesorectal
excision
•Abdomino-perineal
excision with a
permanent colostomy
•Adjuvant
preoperative
radiotherapy
•Liver resection for
liver metastases

61. •Gray’s Anatomy: The Anatomical Basis of
Clinical Medicine
•Gray’s Anatomy for Students
•Richard S. Snell –Clinical Anatomy by Regions
•Keith L. Moore –Essential Clinical Anatomy
•Last’s Anatomy -Regional and Applied
•Frank H. Netter –Atlas of Human Anatomy
•Bailey and Love’s Short Practice of Surgery