Arteries

(I) Abdominal aorta:

• Lower border of T12 – lower border of L4 (aortic hiatus to bifurcation)
• Travels down posterior wall of abdomen
• Runs on the left and parallel to IVC
• At L4 bifurcates

Relations:

• Anterior – Lesser omentum, stomach, pancreas
• Posterior – Vertebral column, lumbar veins
• Right – IVC, azygos vein, cisterna chyli, right crus diaphragm
• Left – Left crus diaphragm, ascending duodenum, small intestines

Clinicals:

• Rupture of abdominal aortic aneurysm – deep pain in abdomen, back pain, hemoperitoneum (blood in peritoneal cavity) – leads to hemorrhagic shock – rapid death

(II) Celiac trunk:

• 1st branch of abdominal aorta – T12
• Divides into 3 branches

(III) Superior mesenteric artery:

• 2nd branch of abdominal aorta – L1
• Posterior to neck of pancreas
• Pass between pancreas head and uncinate process
• Terminates in right iliac fossa as ileocolic artery

(IV) Inferior mesenteric artery:

• 3rd branch of abdominal aorta – L3
• Posterior to left psoas major
• Terminates as superior rectal artery

Clinicals:

• Peptic ulcers – erode gastroduodenal artery, leads to gastrointestinal bleeding
• Celiac trunk compression syndrome – due to median arcuate ligament, leads to ischemia (median arcuate ligament connects right and left crura of diaphragm)
• Splenic artery aneurysm
• Left hemicolectomy – surgical removal of descending colon – dissect branches of IMA and IMV

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Veins

(I) IVC:

• Formed by left and right common iliac veins at L5
• Ascends on right of vertebral column and aorta
• Anterior to right psoas major
• Grooves liver
• Enters through diaphragm at T8 – caval opening

Relations:

• Anterior – Head of pancreas, epiploic foramen, right and caudate lobe liver
• Posterior – Right psoas major, right crus diaphragm, Lower lumbar vertebrae
• Right – Right kidney, right lobe liver
• Left – Abdominal aorta

(II) IVC and SVC communication sites:

1. Thoracoepigastric – connects lateral thoracic vein (axillary vein – SVC) and superficial epigastric vein (femoral vein – IVC)

2. Superior epigastric (internal thoracic – SVC) and inferior epigastric (external iliac – IVC)

3. Azygos venous system

4. Vertebral venous plexus – Lumbar veins (IVC) and posterior intercostal veins (SVC)

(III) Portal vein:

• Formed from superior mesenteric vein and splenic vein – behind neck of pancreas
• Before reaching liver, portal vein divides into right and left branches – divides in to smaller venous branches
• Drains into hepatic sinusoids (supply blood to liver)

Clinicals:

• Portal hypertention – obstruction of blood flow through portal system, blood redirected through portosystematic anastomosis, veins become dilated – varices and hemorrhoids
• Infection of portal vein (pylephlebitis)

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Nerves

(I) Nerves of abdominal wall: Somatic – Parietal peritoneum and skin

1. Anterolateral abdominal wall: Anterior rami of:

• T7-T9 – Skin superior to umbilicus
• T10 – Skin around umbilicus
• T11 – Skin inferior to umbilicus
• T12/Subcostal – Skin inferior to umbilicus
• L1 – Iliohypogastric and ilioinguinal – Skin inferior to umbilicus

2. Posterior abdominal wall:

• T12 – subcostal
• Lumbar (L1-L5): Iliohypogastric and ilioinguinal (L1), Gentitofemoral (L1-L2), Lateral cutaneous femoral (L2-L3), Femoral (L2-L4), Obturator (L2-L4), Lumbosacral trunk (L4-L5)

(II) Nerves of GIT: Visceral – Abdominal viscera and visceral peritoneum

Sympathetic: vasoconstrict blood vessels, decrease peristalsis and digestion, close sphincters of GIT

Parasympathetic: vasodilate blood vessels, increase peristalsis and digestion, stimulate insulin production

NB:

• If a sympathetic nerve is supplying a thoracic viscera – Synapse occurs in sympathetic chain
• If a sympathetic nerve is supplying an abdominal viscera – No synapse, but passes through the chain and synapses at the celiac ganglion, SMG or IMG

1. Presynaptic fibers T5-T9 ⇒ Greater splanchnic nerve – Sympathetic

• Synapse in celiac ganglion
• Post synaptic fibers – pass in celiac plexus – towards branches of celiac trunk and supplies foregut organs

2. Presynaptic fibers T10-T11 ⇒ Lesser splanchnic nerve – Sympathetic

• Synapse in SMG
• Post synaptic fibers – pass in SM plexus – towards branches of SMA and supplies midgut organs

3. Presynaptic fibers T12 ⇒ Least splanchnic nerve – Sympathetic

• Synapse in SMG
• Post synaptic fibers – pass in SM plexus – towards branches of SMA and supplies midgut organs

4. Presynaptic fibers L1-L3 ⇒ Lumbar splanchnic nerve – Sympathetic

• Synapse in IMG
• Post synaptic fibers – pass in IM plexus – towards branches of IMA and supplies hindgut organs

5. Vagus nerve – Parasympathetic

• Presynaptic fibers of vagus – through celiac plexus – synapses at small ganglion of the foregut organ
• Presynaptic fibers of vagus – through SM plexus – synapses at small ganglion of the midgut organ

6. Presynaptic S2,S3,S4 – Pelvic splanchnic nerve – Parasympathetic

• Run in inferior hypogastric plexus – ascend to superior hypogastric plexus – then to inferior mesenteric plexus – along branches of IMA
• Synapse at small ganglion of hindgut organ

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Blood and nerve supply of foregut, midgut and hindgut organs

Foregut organs: Esophagus, stomach, 1st part duodenum, pancreas, liver, gallbladder

• Artery – Celiac trunk
• Nerve – Greater splanchnic, vagus

Midgut organs: Rest of duodenum, jejunum, ilium, cecum, appendix, ascending colon, proximal 2/3 transverse colon

• Artery – SMA
• Nerve – Lesser splanchnic, least splanchnic and vagus

Hindgut organs: Rectum, upper anal canal, descending colon, sigmoid colon, distal 1/3 transverse colon

• Artery – IMA
• Nerve – Lumbar splanchnic, pelvic splanchnic

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Abdomen

Longitudinal section of abdomen:

Supracolic and infracolic connected by paracolic gutters – drain fluid such as pus or bile to outer margins of colon (Clinical – spread infection, tumor deposits from or to pelvis)

Organs are covered by visceral peritoneum. Between parietal and visceral peritoneum is peritoneal fluid (contains electrolytes, antibodies, WBC, glucose)

Clinical: Ascites – fluid accumulation

Regions of abdomen:

Clinicals:

• Pain location, surgical procedures
• Abdominal hernias:

1. Internal – hiatus of diaphragm, epiploic foramen
2. External – inguinal, femoral, obturator

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Anterior abdominal wall

Layers:

• Skin
• Superficial fascia:

1. Above umbilicus – single sheet of connective tissue
2. Below umbilicus – fatty Camper’s fascia then membranous Scarpe’s fascia

• Muscles: enclosed in deep investing fascia

1. External oblique
2. Internal oblique
3. Transverse abdominis

• Fascia transversalis
• Extraperitoneal fatty areolar tissue
• Parietal peritoneum

NB:

• In the centre is rectus muscle
• Scarpe’s fascia continues as Colle’s and Darto’s fascia and is inferiorly attached to fascia lata below inguinal ligament. Therefore when penile urethra injured in men, urine escapes urethra to scrotum and spreads in lower abdominal wall but not to thigh.

Functions:

• Contain and protect abdominal contents
• Increase intraabdominal pressure in micturition, defecation, coughing, sneezing and parturition
• Cause trunkal flexion
• Contribute to venous return

Blood supply:

• Internal thoracic – Superior epigastric, musculophrenic
• Abdominal aorta – Posterior intercostal, subcostal
• External iliac – Inferior epigastric, deep circumflex iliac
• Femoral – Superficial circumflex iliac, superficial epigastric

Nerves: Written in nerves

Lymph: 

• Superficial:

1. Superior to umbilicus – Anterior axillary and parasternal
2. Inferior to umbilicus – Superficial inguinal

• Deep: External iliac, lumbar nodes

Anterior Abdominal wall muscles:

Clinicals:

• Abdominal incision/ Laparotomy – most common is midline incision along linea alba from xiphoid process to umbilicus to pubic symphysis
• Urinary extravasation – penile urethra injured in men, urine escapes urethra to scrotum and spreads in lower abdominal wall but not to thigh
• Venous engorgement – flow in SVC or IVC obstructed, leads to collateral flow
• Ascites
• Caput medusae – engorged superficial epigastric veins
• Liposuction

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Rectus sheath

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Posterior abdominal wall

Fascia:

1. Fascia transversalis
2. Psoas major fascia
3. Thoracolumbar fascia – 3 layers

Clinicals: 

• Psoas abscess – caused by lumbar tuberculosis, infects psoas sheath
• Psoas sign

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Inguinal canal

Superior and parallel to inguinal ligament

Boundaries:

Contents: Ilioinguinal nerve, genitofemoral nerve, round ligament (females), spermatic cord (males)

Inguinal triangle of Hesselbach

Clinicals:

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Peritoneum

Closed sac except in females where infundibulum opens

Layers: Parietal and visceral

Intraperitoneal organs: Stomach, spleen, liver, transverse colon

Retroperitoneal organs: Primary (retro since developed – KER) and secondary (become retro later – SADPUC)

Retroperitoneal viscera:

• S – Suprarenal glands
• A – Aorta and IVC
• D – Duodenum (2nd part)
• P – Pancreas
• U – Ureter
• C – Colon (ascending and descending)
• K – Kidney
• E – Esophagus
• R – Rectum

Ligaments:

• Median umbilical ligament (allantoic duct) – urinary bladder apex to umbilicus
• 2 medial umbilical ligaments (umbilical arteries)
• 2 lateral umbilical ligaments – cover inferior epigastric artery

NB: Umbilical vein – becomes ligamentum teres of liver

Mesenteries: Fold of visceral peritoneum that attatches intraperitoneal organs to posterior abdominal wall. Contains nerves, vessels, lymph nodes and fat

Omenta:

1. Greater omentum – From greater curvature stomach and proximal duodenum ⇒ to infront of small intestines ⇒ Reflects and ascends to transverse colon

Contains: Nerves, vessels, lymph nodes and fat

Parts: Gastrosplenic ligament, gastrophrenic ligament, gastrocolic ligament

Functions:

• Infection and wound isolation
• Limit spread of intraperitoneal infections
• Immunity – macrophages, lymphocytes etc
• Mobility
• Insulation

2. Lesser omentum – From lesser curvature stomach to liver

Parts: Hepatogastric ligament (right and left gastric arteries), hepatoduodenal ligament (Common bile duct, portal vein, hepatic artery)

Peritoneal cavity:

Epiploic foramen – Relations:

• Superior – Caudate lobe liver
• Inferior – 1st part duodenum
• Anterior – Hepatoduodenal ligament
• Posterior – IVC

Clinicals:

• Internal hernia
• Accumulation of blood (ruptured spleen), bile (bile duct) or fecal matter (intestines)
• Peritonitis – infection due to bacterial contamination

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Liver

Ligaments:

Impressions on liver:

Position: Right 1/4, deep to ribs 7-11

Surfaces: Diaphragmatic and visceral

Relations:

• Anterior: Diaphragm, ribcage, falciform ligament
• Posterior: Right kidney and adrenal, gall bladder, esophagus, stomach
• Superior: Diaphragm
• Inferior: Gall bladder

Support structures: Falciform ligament, coronary ligament, ligamentum teres, triangular ligament, hepatoduodenal ligament, lesser omentum and hepatic veins

Blood supply: Right and left hepatic arteries – segmental branches

Venous: Hepatic portal vein – drains to hepatic sinusoids and so to IVC

Nerves: Sympathetic – Greater splanchnic, Parasympathetic – Vagus, right phrenic

Lymphatics: Hepatic, left gastric nodes

Hepatic recesses: 

• Right and left subphrenic spaces – between diaphragm and liver
• Subhepatic space – between inferior surface liver and transverse colon
• Morrison’s pouch/ hepatorenal – between liver and right kidney

Functional divisions of liver:

Clinicals:

• Hepatic lobectomies
• Rupture of liver – fractured rib, hemorrhage
• Liver trauma – tearing of hepatic veins from IVC
• Hepatomegaly – enlarged liver – due to infection, tumours or metabolic disorder
• Liver cirrhosis – health tissue replaced by scar tissue, organ will start to fail, blood cannot easily flow in portal vein
• Liver biopsy – small needle inserted in liver to collect tissue sample
• Jaundice

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Gallbladder

Location: Between right and left lobes, inferior surface of liver

Biliary tree:

Relations:

• Anterior – Inferior surface liver
• Posterior – Transverse colon, proximal duodenum
• Superior – Liver
• Inferior – Biliary tree

Blood: Cystic artery

Venous: Cystic vein, hepatic sinusoids

Nerves: Sympathetic – Greater splanchnic, Parasympathetic – Vagus, right phrenic

Lymph: Hepatic nodes

Clinicals:

• Mobile gallbladder – only attached to cystic duct, risk of torsion
• Cholecystectomy
• Gall stones
• Biliary colic – gall stones block bile duct
• Cholecystitis – inflammation

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Spleen

Impressions:

Surfaces: Diaphragmatic and visceral

Relations:

• Anterior: Stomach
• Posterior: Left kidney and adrenal, ribs 9-11
• Inferior: Left colic flexure

Support structures:

• Gastrosplenic ligament (short gastric vessels) – great curvature to spleen
• Splenorenal ligament (Splenic vessels) – spleen to left kidney
• Phrenicocolic ligament – diaphragm to left colic flexure

Blood supply: Splenic artery – 5 segmental arteries

Venous: Splenic vein

Nerves: Sympathetic – Greater splanchnic, Parasympathetic – Vagus, right phrenic

Lymphatics: Celiac nodes

Clinicals:

• Rupture of spleen – fractured rib, intraperitoneal hemorrhage
• Splenectomy
• Splenomegaly
• Accessory spleen
• Splenic biopsy

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Stomach

Relations: 

• Anterior – Left lobe liver
• Posterior – Lesser sac, spleen, left kidney and adrenal, splenic artery, pancreas, aorta
• Inferior – Transverse colon, left colic flexure

Blood supply:

Nerves: Sympathetic – Greater splanchnic, Parasympathetic – Vagus, right phrenic

Lymphatics:

Clinicals:

• Esophageal varices – portal hypertension
• Pyrosis (heart burn) – due to gastroesophageal reflex disorder (stomach acid flows to esophagus)
• Gastroesophageal reflex disorder – hiatus hernia, delayed gastric emptying, dysfunction of lower esophagus sphincter
• Hiatus hernia – part of stomach protrudes through esophageal hiatus in diaphragm
• Pylorospasm – closure of pylorus due to muscle spasm, due to pyloric ulcers
• Gastrectomy
• Gastric ulcers – erode arteries nearby

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Pancreas

Relations:

Blood supply: Greater pancreatic artery (from splenic artery), Superior and inferior pancreaticoduodenal artery

Nerves: Sympathetic – Greater splanchnic, Parasympathetic – Vagus, right phrenic

Lymphatics: Pancreaticosplenic, pancreaticoduodenal

Clinicals:

• Blocked hepatopancreatic ampulla – gallstone
• Pancreatitis
• Pancreatic ectomy
• Rupture
• Cancer

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Duodenum

From pylorus to duodenojejunal junction

Relations:

Support structures: Hepatoduodenal ligament, ligament of Trietz

Recesses: 

Blood supply: Superior and inferior pancreaticoduodenal, right gastroepiploic

Nerve: Sympathetic – Greater and lesser splanchnic, Parasympathetic – Vagus

Lymphatics: Pancreaticoduodenal nodes, superior mesenteric nodes

Clinicals:

• Duodenal ulcers – erode gastroduodenal artery – hemorrhage
• Paraduodenal hernia – intestinal loops

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Jejunum and ileum

From duodenojejunal junction to ileocecal junction

Blood supply: SMA and vasa recta

Nerves: Lesser splanchnic, least splanchnic and vagus

Clinicals: Ischemia of intestine – occlusion of vasa recta by embolus

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Large intestine

From ileocecal valve in right iliac fossa to anal orifice

NB: Ascending colon has no mesentary

Relations:

Blood supply:

Nerves:

• Lesser splanchnic, least splanchnic and vagus – Cecum, appendix, ascending colon, proximal 2/3 transverse colon
• Lumbar splanchnic and pelvic splanchnic – Distal 1/3 transverse, descending and sigmoid coloc

Lymphatics: Epicolic and paracolicdrain into superior and inferior mesenteric nodes

Clinicals:

• Colitis
• Colectomy
• Ileostomy – artificial opening of ileum through abdominal wall
• Colonoscopy
• Diverticula – pouches form on wall of colon (usually sigmoid) – old people
• Volvulus sigmoid- sigmoid colon twists on sigmoid mesocolon – bowel obstruction

Difference between small and large intestine:

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Appendix

Location: Right iliac fossa, opens in cecum

Relations:

• Anterior – Greater omentum
• Posterior – Psoas major
• Superior – Ileum, mesoappendix (portion of the mesentery connecting the ileum to the appendix)
• Left – Sigmoid colon
• Right – Paracolic gutter, ascending colon

Positions:

Blood supply: Appendicular artery and vein

Nerves: Lesser splanchnic, least splanchnic and vagus

Lymphatics: Superior mesenteric

Clinicals:

• Appendicitis
• Appendectomy
• Psoas test

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Kidneys

Are 3 vertebrae long

Coverings: Superficial to deep

Pararenal fat ⇒ Renal fascia (enclose kidney and suprarenal glands) ⇒ Perirenal fat ⇒ Fibrous renal capsule

Support structures: Splenorenal ligament

Relations:

Anterior:

Posterior:

Blood supply:

Nerves: Lesser splanchnic, least splanchnic and vagus

Lymphatics: Lumbar nodes

Clinicals:

• Perinephric abscess – pus around kidney
• Pelvic kidney
• Horseshoe kidney
• Renal agenesis
• Renal hypoplasia
• Kidney stones/renal calculi – formed in kidney or renal pelvis, may pass through ureter into bladder
• Renal transplant – to lower abdomen, renal vessels connected to recipient external iliac vessels, ureter sutured into urinary bladder
• Nephrectomy
• Floating kidney – abnormal condition in which the kidney drops down into the pelvis when the patient stands up

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Suprarenal glands

Cortex (mesoderm) and medulla (ectoderm – neural crest). Fatty tissue between kidney and suprarenal gland, covered in renal fascia.

Relations:

Right:

• Anterior – Right lobe liver
• Posterior – Right crus diaphragm
• Superior – Liver

Left:

• Anterior – Stomach, pancreas, spleen
• Posterior – Left crus diaphragm
• Superior – Spleen

Blood supply: Superior, middle and inferior suprarenal

Venous: Right and left suprarenal

Nerves: Greater splanchnic, lesser splanchnic

Lymphatics: Lumbar nodes

Right and left difference:

Right – Triangular shape, loosely attached to superior pole kidney

Left – Cresent shape, superior and middle border can extend to renal hilum

Clinicals:

• Tumor of medulla
• Addison’s disease – low cortisol and aldosterone
• Cushing’s syndrome – elevated cortisol

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Ureter

Course:

• Continuation of renal pelvis
• Posterior to renal vessels
• Anterior to psoas major
• Gonadal vessels cross over it from medial to lateral
• Cross infront of common iliac bifurcation
• Opposite sacroiliac joint
• Opposite ischial spine, curves anteromedial to open into posterior superior part of bladder
• Runs an oblique 2cm course in urinary bladder wall – forms valve like mechanism

Blood supply:

Nerves: Renal plexus, superior hypogastric plexus, T11-L2

Lymphatics: Lumbar, common iliac, external iliac, internal iliac

Relations:

Clinicals:

• Retrocanal ureter – Right ureter passes posterior to IVC, disturbs drainage from right kidney
• Kidney stones – Obstruct urine flow

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Others

1. Lumbar triangle:

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2. Calot’s triangle/Cystohepatic triangle:

Content: Cystic artery

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3. Triangle of doom:

Contents:

• External iliac vessels
• Deep circumflex iliac vein
• Femoral nerve
• Genital branch of genitofemoral nerve

Clinicals: Inguinal hernia – nerves damaged when repairing a hernia by sutures or staples

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4. Triangle of pain:

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5. Triangle of safety:

For intercostal catheter placement

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6. Modification of fascia transversalis:

• Femoral sheath and ring – anterior
• Deep inguinal ring – posterior
• Internal spermatic fascia in testis

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7. Mcburney’s point:

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8. Mechanisms to prevent inguinal hernia:

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These are summarized notes from various sources, mainly TeachMeAnatomy and Wikipedia