The document provides an overview of the anatomy of the abdomen, including: 1) It describes the surface anatomy of the abdomen using planes and regions. 2) It details the layers of the anterior abdominal wall including muscles and fascia. 3) It explains the anatomy of the inguinal canal including its walls, openings, contents and Hasselbach's triangle. 4) It briefly outlines the muscles and fascia of the posterior abdominal wall.

1. ABDOMEN
ANATOMY OF
Dr. Rajith Eranga
www.rermedapps.com

2. SURFACE ANATOMY – 9 Regions
A. Midclavicular Plane
Vertical line joining the mid-points of
clavicles to mid-inguinal points.
B. Transpyloric Plane (L1)
Horizontal line joining the mid-point
between jugular notch & pubic symphysis.
C. Intertubercular Plane (L5)
Horizontal line joining the two iliac tubercles.
A
B
C
A

3. SURFACE ANATOMY - Planes
1. Transpyloric Plane – L1
• Pylorus of Stomach
• Neck of Pancreas
• Fundus of Gallbladder
• Renal Hilum
• Duodenojejunal flexure
• End of Spinal Cord (adult)
2. Subcostal Plane – L3
• Origin of Inferior mesenteric artery
3. Supracristal Plane – L4
• Bifurcation of Aorta

4. ANTERIOR ABDOMINAL WALL - Layers
1
2
3
4
5
6
7
89

5. 1. External Oblique
2. Internal Oblique
3. Transversus Abdominis
4. Rectus Abdominis
5. Pyramidalis
ANTERIOR ABDOMINAL WALL - Muscles
Rectus Sheath

6. INGUINAL CANAL – Basic Anatomy
• It is an oblique intermuscular passage in
the lower abdominal wall, located parallel
& just above the medial half of the
inguinal ligament.
• Extends from the deep inguinal ring to
the superficial inguinal ring.
• Directed downwards, forwards &
medially.
• 4 cm in length. Larger in males.

7. RAJITH ERANGA
Anterior Wall
Full Extent
• Skin
• Superficial fascia
• External Oblique Aponeurosis
Lateral 1/3
• Fibres of Internal oblique muscle M
L
INGUINAL CANAL - Walls

8. RAJITH ERANGA
Floor
Formed by
1. Medial part of inguinal ligament.
2. Lacunae ligament at the medial
end.
INGUINAL CANAL - Walls

9. RAJITH ERANGA
Roof
Formed by the arching fibres
of the
1. Internal Oblique
2. Transverse Abdominis
muscles.
INGUINAL CANAL - Walls

10. RAJITH ERANGA
Posterior Wall
Full Extent
• Fascia Transversalis
• Extraperitoneal fat
• Parietal peritoneum
Medial 2/3
• Conjoint tendon
• Reflected part of the inguinal ligament
M
L
INGUINAL CANAL - Walls

11. RAJITH ERANGA
Deep (Internal) Inguinal Ring
• Opening in the posterior wall
• Defect in the transversalis fascia
• Demarcated medially by the
inferior epigastric artery
INGUINAL CANAL - Openings

12. RAJITH ERANGA
Superficial (External) Inguinal Ring
• Opening in the anterior wall
• Defect in the External oblique
aponeurosis
• Above & medial to pubic tubercle
INGUINAL CANAL - Openings

13. RAJITH ERANGA
INGUINAL CANAL – Hasselbach’s Triangle
Borders
• Medial – Lateral border of Rectus
abdominis (Linea Semilunaris)
• Lateral – Inferior epigastric artery
• Inferior – Inguinal ligament
Importance
• Potential weakness of the wall
• Direct Inguinal Hernia – Entry point

14. RAJITH ERANGA
• Spermatic Cord – In Males
• Round Ligament of the Uterus – In Females
INGUINAL CANAL - Contents

15. • Spermatic Cord – In Males
• Round Ligament of the Uterus – In Females
• Ilioinguinal Nerve – In Both
(not coming through deep inguinal ring)
INGUINAL CANAL - Contents

16. POSTERIOR ABDOMINAL WALL
Muscles
1. Diaphragm
2. Quadratus Lumborum
3. Psoas Major
4. Psoas Minor (60%)
5. Iliacus

17. THORACO LUMBAR FASCIA
Investing fascia of back muscles of thorax &
abdomen. Continues above with nuchal fascia.
3 Layers
Anterior, Middle, Posterior
It Encloses
Psoas, Quadrates Lumborum, Erector spinae,
Multifidus.
Gives Attachments to
Trapezius, Latissimus dorsi, Gluteus maximus
Internal oblique, Transversus abdominis

18. PERITONEUM – Basic Anatomy
Serous membrane lining abdominal cavity & viscera.
Layers
1. Parietal – Somatic mesoderm
2. Visceral – Splanchnic mesoderm
Functions
1. Convey neurovascular bundle
2. Lubrication – Prevent friction while moving
3. Maintain position of organs

19. INTRAPERITONEAL Vs RETROPERITONEAL
Intraperitoneal Organs
Wrapped by visceral peritoneum completely.
Eg: Spleen, Liver, Stomach, Jejunum
Retroperitoneal Organs
Covered with peritoneum only anteriorly.
1. Primarily Retroperitoneal
Kidney, Adrenal
2. Secondarily Retroperitoneal
Ascending & Descending colons
PosteriorAbdominalWall

20. PERITONEAL REFLECTIONS
1. Mesenteries
Suspends organs to posterior abdominal wall
A. The mesentery (of the small intestine)
B. Transverse Mesocolon
C. Sigmoid Mesocolon
D. Meso-appendix

21. PERITONEAL REFLECTIONS
2. Omenta
Attach Stomach & proximal duodenum
to other organs.
• Lesser Omentum (2 Layered)
From lesser curvature to liver
• Greater Omentum (4 layered)
From greater curvature to
transverse mesocolon

22. PERITONEAL REFLECTIONS
3. Ligaments
Attach organs to other organs or wall.
• Phrenicocolic ligament
• Gastrosplenic ligament
• Splenorenal ligament
• Falciform ligament
• Gastrohepatic ligament
• Hepatoduodenal ligament
Lesser
Omentum

23. PERITONEAL CAVITY - Divisions
1. Greater Sac
1. Supracolic compartment
2. Infracolic compartments (Left & Right)
2. Lesser Sac (Omental Bursa)
• Supracolic & Infracolic compartments are
connected by R & L paracolic gutters.
• Greater & Lesser sacs are connected by
Epiploic foramen (of Winslow).
Potential space between parietal & visceral peritoneum.

24. EPIPLOIC (OMENTAL) FORAMEN
Borders
• Superior – Caudate lobe
• Inferior – Duodenum (1st Part)
• Anterior – Hepatoduodenal ligament
(containing bile duct, hepatic artery,
portal vein)
• Posterior - IVC
Importance
Pringle’s manoeuvre
Lesser sac communicates with greater sac via this.

25. PERITONEAL RECESSES
a. Lesser Sac (omental bursa)
b. Subphrenic Spaces
1. Right
2. Left
c. Subhepatic Spaces
1. Right (Morrison’s pouch)
2. Left
d. Paraduodenal fossae - 4
e. Retrocecal fossa
f. Intersigmoid fossa

26. STOMACH – Basic Anatomy
2 Surfaces, 2 curvatures, 2 notches, 2 omenta, 2
sphincters. It has Cardia, Body, Fundus, Pylorus
(Pyloric canal + Antrum).
Sphincters
1. Upper (cardiac) – Physiological – at T11
• Acute angle
• Mucosal fold
• Right crus of diaphragm
• Positive intraabdominal pressure
2. Lower (pyloric) – Anatomical - at L1

27. STOMACH BED
1. Lesser sac
2. Left Crus of Diaphragm
3. Pancreas
4. Spleen
5. Left Kidney
6. Left Suprarenal
7. Splenic artery
8. Transverse Colon
9. Transverse Mesocolon

28. STOMACH – Blood Supply
Lesser Curvature
1. Left Gastric artery
2. Right Gastric artery
Greater Curvature
3. Left Gastroepiploic artery
4. Right Gastroepiploic artery
5. Short gastric arteries

29. STOMACH – Blood Supply
To Portal Vein
1. Left Gastric vein
2. Right Gastric vein
To Superior Mesenteric Vein
3. Left Gastroepiploic vein
To Splenic Vein
4. Right Gastroepiploic vein
5. Short gastric veins

30. STOMACH – Lymph Drainage
• Superior 2/3
Directly to Coeliac nodes
• Inferior 1/3 – Right side 2/3
Subpyloric nodes  Coeliac nodes
• Inferior 1/3 – Left side 1/3
Suprapancreatic nodes  Coeliac
nodes

31. STOMACH – Nerve Supply
Autonomic
• Parasympathetic – Vagus
• Sympathetic – Coeliac plexus
Vagal Trunks
• Left vagus  Anterior trunk
• Right vagus  Posterior trunk
Functions
• Motor
• Secretomotor

32. INTESTINE
Foregut - Coeliac trunk
Up to major duodenal papilla (2nd
Duodenum)
Midgut – Superior Mesenteric Artery
Up to proximal 2/3 of transverse colon
Hindgut – Inferior Mesenteric Artery
Beyond that point

33. DUODENUM – Basic Anatomy
C shaped, 25 cm long, 4 parts
First Part – 5 cm (at L1)
• Duodenal cap
• Ascends upward
• First 2.5 cm – Intraperitoneal
• Portal triad posterior to it
L1
L2
L3

34. DUODENUM – Basic Anatomy
C shaped, 25 cm long, 4 parts
Second Part – 7.5 cm (L1- L3)
• Descends vertically
• Halfway down – Bile duct & Main
pancreatic duct opens into it.
Major duodenal papilla
• Crossed by Transverse colon
• Posteriorly – Right Renal hilum
L1
L2
L3

35. DUODENUM – Basic Anatomy
C shaped, 25 cm long, 4 parts
Third Part – 10 cm (at L3)
• Transversely running to left
• Anteriorly – Superior mesenteric
vessels
• Posteriorly – Aorta & IVC
L1
L2
L3

36. DUODENUM – Basic Anatomy
C shaped, 25 cm long, 4 parts
Fourth Part – 2.5 cm (L3 - L2)
• Ascends upward
• Ligament of Trietz
R crus to duodnojejunal junction
L1
L2
L3

37. DUODENUM – Blood Supply
Site of anastomosis (Watershed)
between foregut & midgut
vessels.
Coeliac trunk 
Superior Pancreatico duodenal
+
Superior Mesenteric Artery 
Inferior Pancreatico duodenal

38. JEJUNUM & ILEUM
JEJUNUM ILEUM
Diameter Larger Smaller
Wall Thicker Thinner
Region Umbilical Suprapubic
Mesentery Less fat & thin More fat & thicker
Vessels 1 or 2 Arcades Multiple arcades
Lumen Plicae circularis Peyer’s patches
Histology Tall villi, Deep crypts Short villi, shallow crypts

39. CAECUM
• Below ile-ocaecal valve
• Usually intraperitoneal
• 3 teniae meet at the base of
appendix
• Retrocaecal fossa behind it

40. APPENDIX
• A diverticulum
• At McBurney’s point
• Meso-appendix – Appendicular
artery (from ileocolic artery)
• End arterial supply – Gangrene!
• Usually retrocaecal.
Appendicectomy
Using Gridiron or Lanz incision

41. COLON
Length - 150cm
Parts
1. Ascending colon - Retroperitoneal
2. Transverse colon - Intraperitoneal
3. Descending colon - Retroperitoneal
4. Sigmoid colon - Intraperitoneal
Structure
• Omental appendices
• Tinae coli - 3
• Haustrations

42. SPLEEN
• Lies on 9, 10, 11 ribs
• Becomes palpable when it is twice normal
size
• Thin capsule
• Splenic notch in anterior border
• Related closely to stomach, splenic flexure,
left kidney & tail of pancreas
• Splenorenal ligament - splenic vessels
• Gastrosplenic ligament - short gastric vessels

43. LIVER – Basic Anatomy
Largest solid organ (1.5Kg)
Location
Right Hypogastrium + Epigastrium + Left
Hypogastrium
Lobes
1. Right lobe (largest)
2. Left lobe
3. Caudate lobe
4. Quadrate lobe

44. LIVER – Peritoneal Attachments
• Falciform ligament & Ligamentum
teres – to abdominal wall
• 2 Coronary ligaments (Ant & Post
folds) – demarcates bare area
• 2 Triangular ligaments (L & R) –
attach to diaphragm
• Lesser omentum – attach to
stomach
Bare Area of Liver

45. LIVER – Porta Hepatis
• Area on under surface
• Cross-bar of ‘H’
• Structures enter/leave liver
• Peritoneum is reflected around it
Contents
• Hepatic artery
• Common hepatic duct
• Portal vein
• Lymphatics & LN
• Autonomic nerves

46. LIVER – Blood Supply
Dual blood supply
1. Hepatic artery (25%)
2. Portal vein (75%)
Venous drainage
Central veins
Collecting veins
Hepatic veins IVC

47. LIVER – Nerve Supply & Lymph Drainage
Nerve Supply
• Capsule (Glisson’s capsule)
Lower intercostal nerves
• Liver Parenchyma
Hepatic plexus (Celiac plexus + Vagus)
Lymph drainage
• Anterior aspect - Hepatic LN Cysterna Chyli
• Posterior aspect - Posterior mediastinal LN (via bare area)

48. GALLBLADDER
• Bile reservoir (50ml)
• In GB Fossa (Between Right & quadrate lobes)
• Fundus, Body, Neck, Cystic duct
• Blood supply – Cystic artery & Liver bed
Clinicals
• Murphy’s sign - Read
• Courvoisier's law - Read
• Cholecystitis – Inflammation of GB
• Cholangitis – Inflammation of bile duct
• Charcot’s triad – Fever + Jaundice + RUQ pain

49. BILLIARY SYSTEM
Calot’s Triangle
• Between Cystic duct,
Common hepatic duct & Liver.
• Cystic artery is located here.
• Important in cholecystectomy.
• R & L hepatic duct  Common Hepatic duct
• Common hepatic duct + Cystic duct  Bile duct
• Bile duct opens to 2nd part of duodenum with
main pancreatic duct at ampulla of Vater
• It is guarded by sphincter of Oddi

50. PANCREAS
• Retroperitoneal
• Exocrine + Endocrine gland
• Head, Uncinate process, Neck, Body, Tail
Relations & Development (Read)
Ducts
1. Main duct – at Amulla of Vater
2. Accessory duct - Proximally
Clinicals
• Pancreatic CA - Bile duct obstruction
• Annular Pancreas - Duodenal obstruction
• Pancreatic pseudocyst

51. KIDNEYS – Basic Anatomy
• Retroperitoneal
• From T12 to L3 (Hilum at L1)
• Parenchyma  Cortex & Medulla
• Cortex extends to Medulla = Pyramids
• Apex of Pyramids = Renal Papilla
• Renal papilla  Minor Calyx  Major
Calyx  Renal Pelvis Ureter

52. KIDNEYS – Renal Fascia & Fat
From deep to superficial

53. KIDNEYS – Arterial Supply
Renal arteries (from aorta)  Divides at hilum
• Anterior – 75%
• Posterior – 25%
• Five Segmental arteries from them
These arteries are end arteries!
Segmental arteries divides further…
Segmental  Interlobar  Arcuate 
interlobular Afferent arterioles
 Glomerulus

54. URETERS
• 25 cm long
• Retroperitoneal, adhered to peritoneum
• 3 parts – Abdominal, Pelvic & Intravesical
Sites of Potential Obstruction of Calculi
1. Pelviureteric junction
2. Pelvic Brim
3. Vesicoureteric junction

55. URETERS - Relations
Posteriorly
• Psoas (medial border)
• Transverse processes of L2-L5
• Sacroiliac joint
• Bifurcation of common iliac Artery
• Genitofemoral nerve
Anteriorly
• 2nd Duodenum
• Gonadal vessels
• Right colic vessels
• Ileocolic vessels

56. SUPRARENAL GLANDS - Layers
Cortex – Mesoderm
1. Zona Glomerulosa
2. Zona Fasciculata
3. Zona Reticularis
Medulla – Ectoderm (Neural crest cells)

57. SUPRARENAL GLANDS – Vasculature
Arterial Supply – 3 arteries
1. Superior adrenal artery  Inferior Phrenic
2. Middle adrenal artery  Abdominal Aorta
3. Inferior adrenal artery  Renal Artery
Venous Drainage – Single vein
1. Left side – to Left Renal vein  IVC
2. Right side  IVC

58. ARTERIES OF ABDOMEN (AORTA)
Branches
Anterior Branches (Unpaired)
1. Coeliac trunk (L1)
2. Superior Mesenteric (L1)
3. Inferior Mesenteric (L3)
Lateral Branches (Paired)
1. Inferior Phrenic Arteries
2. Lumbar Arteries (4 pairs)
3. Renal arteries
4. Supra renal arteries
5. Gonadal arteries
At L4  Bifurcate to two common iliac
arteries + Median sacral artery

59. ARTERIES OF ABDOMEN (AORTA)
Coeliac Trunk – L1
Branches
1. Left Gastric Artery
2. Splenic Artery
3. Common Hepatic Artery

60. ARTERIES OF ABDOMEN (AORTA)
Superior Mesenteric Artery – L1
Branches
1. Inferior Pancreaticoduodenal
2. Middle Colic artery
3. Right Colic artery
4. Ileocolic artery

61. ARTERIES OF ABDOMEN (AORTA)
Inferior Mesenteric Artery – L3
Branches
1. Left colic artery
2. Sigmoid artery
3. Superior rectal artery

62. SYSTEMIC VENOUS DRAINAGE - ABDOMEN
Tributaries of IVC
1. Hepatic veins
2. Inferior phrenic veins
3. Renal veins
4. Lumbar veins
5. Right supra renal veins
6. Right gonadal vein
7. Common iliac veins (terminal) – L5
To IVC  Extends from L5 to T8

63. PORTAL VENOUS SYSTEM
Portal vein is formed at L2 by union of
1. Splenic vein
2. Superior mesenteric vein
Inferior mesenteric vein joins
splenic vein
Direct Tributaries of Portal vein
1. R & L gastric veins
2. Cystic veins
3. Paraumbilical veins
(Refer venous drainage of stomach)

64. PORTO-SYSTEMIC ANASTAMOSIS
These collateral pathways open up in portal
hypertension shunting portal blood o systemic
circulation bypassing liver.
1. Lower Oesophagus
2. Upper Anal Canal
3. Around Umbilicus
4. Bare Area of Liver
5. Patent Sinus Venosus
6. Retroperitoneum

65. THANK YOU 
END OF THE LECTURE