🔥 LIVER — 20% THAT GIVES 80% MARKS

1. Basic Facts

• Largest gland in the body — ~1500 g
• Receives ~1500 mL blood/minute
• Lies mainly in right hypochondrium + epigastrium
• Has 2 surfaces: Diaphragmatic + Visceral

2. Key Surfaces and Borders

Diaphragmatic surface

• Smooth, convex
• Subdivided (no sharp boundaries) into:
• Anterior
• Superior
• Posterior
• Right

Inferior border

• Sharp
• Notched by ligamentum teres
• Separates diaphragmatic from visceral surface

3. Peritoneal Attachments (SUPER HIGH YIELD)

• Liver develops in ventral mesogastrium → remains attached by folds

Falciform ligament

• Contains ligamentum teres in lower free border
• Ascends → becomes left triangular ligament

Coronary ligament

• Right leaf of falciform ligament → forms upper layer
• Creates bare area triangle

Right triangular ligament

• Apex where coronary ligament layers meet

Lesser omentum

• Attaches to fissure of ligamentum venosum and porta hepatis

4. H-SHAPED FISSURES (EXAM FAVOURITE)

When posterior + visceral surfaces seen together → H-shape:

Cross-bar = Porta hepatis

• Hepatic ducts
• Hepatic artery branches
• Portal vein branches
• Lymph nodes
• Nerves
• Order: V–A–D (vein deepest, duct most anterior)

Right limb

• IVC (posterior)
• Gallbladder (inferior surface)

Left limb

• Ligamentum venosum fissure
• Ligamentum teres fissure

5. Caudate Lobe (MUST KNOW)

• Lies between fissures of ligamentum venosum + ligamentum teres
• Partly separated from liver because fissure goes deeply into parenchyma
• Has:
• Anterior surface forming posterior wall of lesser sac fissure
• Caudate process → connects to right lobe between porta hepatis and IVC

6. Key Relations (SUPER HIGH YIELD)

Bare area

• Contact with:
• Diaphragm
• Right suprarenal gland

Visceral surface touches:

• Stomach
• Duodenum
• Hepatic flexure (colon)
• Right kidney

Special impressions:

• Gastric impression
• Renal impression
• Duodenal impression
• Colic impression
• Oesophageal impression (posterior)

7. Gallbladder & Quadrate Lobe

• Gallbladder sits in fossa on visceral surface
• Quadrate lobe lies between:
• Gallbladder fossa
• Fissure for ligamentum teres

8. Hepatic Veins (Surgical Gold)

• Entirely intrahepatic
• Drain into IVC inside its liver groove
• Support the liver’s position

9. Surgical Must-Know

• To expose upper stomach + abdominal oesophagus:

→ Divide left triangular ligament

• Lesser omentum contains:
• Hepatic artery
• Portal vein
• Bile ducts
• In surgery ducts are most anterior, so easiest to access

📌 One-Page Ultra-Condensed Memory Map

SURFACES

• Diaphragmatic (smooth convex)
• Visceral (irregular, impressions)

BORDERS

• Inferior → sharp, ligamentum teres notch

LIGAMENTS

• Falciform → left triangular
• Coronary → bare area
• Right triangular
• Lesser omentum → porta hepatis

H-SHAPE

• Right limb → IVC + Gallbladder
• Left limb → Lig venosum + Lig teres
• Cross-bar → Porta hepatis (V-A-D)

LOBES

• Caudate lobe behind lesser omentum
• Quadrate between GB + lig teres fissure

RELATIONS

• Bare area → diaphragm + right suprarenal
• Visceral → stomach, duodenum, hepatic flexure, R kidney

SURGERY

• Divide left triangular ligament → retract left lobe

🔥 LIVER — SURFACE MARKING & LOBES (20% → 80% marks)

1. Surface Marking — SUPER HIGH YIELD

Upper Border

• Roughly at the xiphisternal joint
• Arches upwards on both sides
• Left side → reaches 5th intercostal space, 7–8 cm from midline
• Right side → reaches 5th rib

Right Border

• Extends from ribs 7 to 11 in the midaxillary line

Inferior Border

• Line connecting:
• Right lower end (costal margin)
• Upper left end
• Central part:
• Lies behind the upper abdominal wall
• About one hand’s breadth below the xiphisternal joint
• Much of it lies along the right costal margin

➡️ KEY IDEA:

Most of the liver is hidden behind ribs — except a small part of the inferior border which may be palpable below the costal margin.

2. Lobes — EXAM GOLD

Traditional Anatomical Division (NOT FUNCTIONAL)

Uses peritoneal landmarks:

• Anterior surface:

Division by falciform ligament

• Visceral surface:

Division by fissures for:

1. Ligamentum teres
2. Ligamentum venosum

Therefore in classical anatomy:

• Right lobe includes:
• Caudate lobe (between IVC & ligamentum venosum)
• Quadrate lobe (between gallbladder & ligamentum teres)

⚠️ BUT THIS IS NOT FUNCTIONALLY CORRECT.

3. Functional Liver Division — CLINICAL MUST KNOW

Functional right & left halves are divided by:

A vertical–oblique plane through:

1. Centre of gallbladder bed
2. Groove for inferior vena cava

Important landmark in this plane:

➡️ Middle hepatic vein

• Runs exactly in the true functional dividing plane
• Key landmark in:
• Ultrasound
• CT
• Surgery
• Segmental liver anatomy

🔥 LIVER SEGMENTS — 20% → 80% MARKS

1️⃣ Four Hepatic Sectors (Surgical Must-Know)

Based on blood supply + biliary drainage, the liver has 4 major sectors:

1. Left lateral
2. Left medial
3. Right medial
4. Right lateral

How to identify them (super high yield):

• Left lateral sector

→ Left of falciform ligament + ligamentum teres/venosum fissures

• Left medial sector

→ Between falciform ligament line AND plane of gallbladder → IVC

• Right medial vs Right lateral

→ Boundary has NO external marking

→ Plane runs obliquely toward the IVC groove

→ Right hepatic vein lies in this plane

2️⃣ Eight Couinaud Segments (Exam Gold)

Liver is divided into 8 segments (I–VIII):

KEY PATTERN TO REMEMBER

• Segment I = Caudate lobe
• Special because:
• Gets blood from both right & left hepatic artery + portal vein
• Drains bile into both ducts
• Drains venous blood directly into IVC
• → Fully autonomous
• Left lateral sector:
• Segment II = posterior
• Segment III = anterior
• Left hepatic vein between II and III
• Left medial sector:
• Segment IV (Quadrate region on visceral surface)
• Subdivided into:
• IVa = superior
• IVb = inferior (matches quadrate lobe)
• Right medial sector:
• Segment V = inferior
• Segment VIII = superior
• Right lateral sector:
• Segment VI = inferior
• Segment VII = superior

3️⃣ Orientation Pattern (Important for Imaging)

When viewed from below (visceral surface):

➡️ Segments run anticlockwise around the porta hepatis

(from II → III → IVb → V → VI → VII → VIII)

This anticlockwise pattern is very testable in radiology anatomy questions.

4️⃣ Mini-Map (1-Minute Total Recall)

SECTORS

• Left lateral → II & III
• Left medial → IV (IVa/IVb)
• Right medial → V & VIII
• Right lateral → VI & VII
• Caudate (I) = independent

VEINS AS GUIDES

• Middle hepatic vein → divides right & left functional lobes
• Right hepatic vein → divides right medial & right lateral sectors
• Left hepatic vein → divides II & III

🔥 LIVER BLOOD SUPPLY

1️⃣ Dual Blood Supply (Central Concept)

The liver receives two inflows:

(A) Hepatic Artery → Oxygenated blood (25%)

• Enters liver at porta hepatis
• Divides into:
• Right hepatic artery → medial & lateral sectoral branches
• Left hepatic artery → medial & lateral sectoral branches

(B) Portal Vein → Nutrient-rich blood (75%)

• Brings absorbed digested products
• Divides similarly into right & left → sectoral branches
• Supplies sinusoids for metabolism

➡️ KEY IDEA:

Arteries = oxygen → 25%

Portal vein = nutrients → 75%

2️⃣ Common Arterial Variations (EXAM GOLD)

Replaced or accessory hepatic arteries:

• Right hepatic artery from SMA → 15%
• Left hepatic artery from left gastric → 20%
• Common hepatic artery may arise from SMA or aorta

→ Tends to run behind portal vein

These variations must be known for:

• Cholecystectomy
• Liver transplantation
• Hepatobiliary surgery

3️⃣ Pringle’s Manoeuvre (Must Know for Surgery)

To control liver bleeding:

Compress the portal triad (hepatic artery + portal vein + bile duct):

• Finger through epiploic foramen (foramen of Winslow)
• Thumb anterior to right free edge of lesser omentum

➡️ Stops inflow to liver → reduces bleeding in trauma.

4️⃣ Arterial Supply is Segmental → End Arteries

• No communication between right & left halves
• Arteries = end arteries

→ Ligation → risk of infarction

But:

• Collaterals may form across bare area from phrenic vessels

Clinical pearl:

Hepatic artery ligation for tumor control sometimes works because of these collaterals.

5️⃣ Hepatic Veins (Outflow System)

Three main veins drain into IVC:

1. Right hepatic vein
2. Middle hepatic vein
3. Left hepatic vein

Key facts:

• Middle hepatic vein lies in functional midplane (between functional right & left)
• Middle often joins left hepatic vein before IVC
• All hepatic veins are entirely intrahepatic
• Open directly into IVC just below diaphragm

Accessory hepatic veins:

• Drain lower parts of liver
• Caudate lobe has its own independent vein → another sign of its autonomy

6️⃣ Portal–Systemic Venous Anastomoses

Small channels connect:

• Portal vein branches

→ across the bare area

→ to azygos system (systemic veins)

Clinical relevance:

Portal hypertension → collateral formation.

🔥 LIVER LYMPH & NERVE SUPPLY — 20% → 80% Marks

1️⃣ Lymph Drainage — SUPER HIGH YIELD

A. Main lymph pathway (most important)

• Primary lymph nodes:

→ Hepatic nodes located in the porta hepatis

(also receive lymph from gallbladder)

• Drainage direction:
1. Down along hepatic artery
2. → Pyloric nodes
3. → Coeliac nodes (final major abdominal station)

B. Additional lymph pathways (HIGH YIELD extras)

1. Bare area drainage

• Lymphatics from bare area →

→ communicate with extraperitoneal lymphatics

→ pass through diaphragm

→ drain into posterior mediastinal nodes

➡️ Clinical implication:

Liver disease (e.g., metastasis) can spread into chest lymph nodes.

2. Ligament pathways

Lymphatics run through:

• Left triangular ligament
• Falciform ligament

→ Connect to diaphragmatic lymphatics and thoracic nodes.

📌 Ultra-condensed lymph summary

• Main: Hepatic nodes → pyloric nodes → coeliac nodes
• Extras:
• Bare area → posterior mediastinum
• Falciform/left triangular → diaphragm lymphatics

2️⃣ Nerve Supply — EXAM GOLD

Sympathetic (pain, vasomotor)

• From coeliac ganglia
• Travel with hepatic artery in lesser omentum
• Enter liver at porta hepatis

Parasympathetic (vagal)

• From anterior vagal trunk
• Via hepatic branch
• Travel through lesser omentum to porta hepatis

🔥 LIVER MICROSTRUCTURE — 20% → 80% Marks

1️⃣ Classical vs Real Lobule (EXAM GOLD)

Classical (textbook) hepatic lobule

• Hexagonal
• Central vein in the centre
• Portal triads at corners
• Hepatocyte plates radiate toward central vein
• Sinusoids run between plates

⚠️ BUT — In humans this “perfect hexagon” rarely exists.

2️⃣ Portal Lobule (More anatomically accurate)

• Portal triad at the centre
• Hepatic vein tributaries at the periphery
• Represents a polygonal area including parts of ≥3 classical lobules

➡️ KEY IDEA:

Portal lobule = bile drainage unit

(center = bile duct → edges = central veins)

3️⃣ Sinusoids & Kupffer Cells (High Yield)

• Sinusoids are lined by fenestrated endothelium
• Fenestrations allow plasma (not blood cells) to enter perisinusoidal space (Space of Disse)
• Enables rapid exchange between plasma ↔ hepatocytes
• Kupffer cells (specialized macrophages) sit in sinusoid lining

→ Responsible for phagocytosis, part of RES.

4️⃣ Bile Flow — Opposite to Blood Flow (Must Know)

Sequence:

1. Hepatocytes produce bile
2. → enters bile canaliculi (between adjacent hepatocytes)
3. → drains into bile ductules of portal triad
4. → forms intrahepatic bile ducts

➡️ KEY IDEA:

Blood flows inward (portal triad → central vein).

Bile flows outward (canaliculi → portal triad).

5️⃣ Capsule & Portal Canals

• Liver covered by thin connective tissue capsule
• At porta hepatis, capsule sends sheaths around:
• Hepatic artery branches
• Portal vein branches
• Bile ducts
• These run inside liver in connective tissue channels called portal canals

➡️ Portal canal = triad + connective tissue

🔥 LIVER DEVELOPMENT — 20% → 80% Marks

1️⃣ Origin — Key Concept

• Liver develops from a Y-shaped endodermal diverticulum growing from the foregut
• This diverticulum grows into the septum transversum

➡️ Core embryology:

Foregut endoderm → liver + biliary tree

Septum transversum mesoderm → stroma + capsule + sinusoids

2️⃣ Septum Transversum Fate (HIGH YIELD)

The septum transversum divides into:

• Cranial part → Pericardium + central tendon of diaphragm
• Caudal part → Ventral mesogastrium (future lesser omentum + falciform ligament)

➡️ Liver grows into the ventral mesogastrium, explaining adult ligaments.

3️⃣ Formation of Bile Duct System

Primary hepatic diverticulum → becomes:

• Bile duct (initial stalk)
• Right hepatic duct (from right limb of Y)
• Left hepatic duct (from left limb of Y)

Secondary outgrowth:

• Cystic diverticulum → forms:
• Cystic duct
• Gallbladder

Repeated branching:

• Hepatic ducts → interlobular ducts → intralobular ductules

➡️ KEY IDEA:

All biliary ducts arise from endodermal branching of the original liver bud.

4️⃣ Fetal Circulation (Just the idea required)

• Liver is partially bypassed by ductus venosus, which connects the umbilical vein → IVC

(This is referenced elsewhere, but the concept is important for understanding development.)

🔥 LIVER — BIOPSY, RESECTION & TRANSPLANTATION (20% → 80% Marks)

1️⃣ Liver Biopsy — SUPER HIGH YIELD

Where to insert needle

• Right 8th or 9th intercostal space
• Midaxillary line

Needle path

• Below lung → through costodiaphragmatic recess
• Through diaphragm
• Across peritoneal cavity
• Into liver

Must NOT advance > 6 cm

➡️ To avoid entering inferior vena cava

Possible complications

• Pneumothorax
• Kidney, colon or pancreas injury
• Needle-track cancer seeding (if malignant lesion)

2️⃣ Hepatectomy (Liver Resection) — EXAM GOLD

Right Hemi-Hepatectomy

• Resection line: Left of gallbladder → right side of IVC
• Removes Segments V–VIII + gallbladder
• Preserve: middle + left hepatic veins

Left Hemi-Hepatectomy

• Removes Segments II, III, IV + most of caudate lobe
• Gallbladder may remain
• Back resection line = left of IVC
• Preserve: right hepatic vein (and usually middle)

Extended resections

• Left hepatectomy + Segments V & VIII
• Right hepatectomy + Segment IV
• Segmental resection if disease is localized

➡️ Segments guide surgery — not classical lobes.

3️⃣ Liver Transplantation — HIGH YIELD OVERVIEW

Standard transplantation includes:

• Remove patient’s liver with attached IVC segment
• Use venovenous bypass:
• Portal vein → femoral vein → axillary vein

Sequence of anastomoses

1. Suprahepatic IVC
2. Infrahepatic IVC
3. Portal vein (release clamps)
4. Hepatic artery
5. Bile duct (two options):
• End-to-end common bile duct
• Donor bile duct → recipient jejunum (Roux loop)

Paediatric special case

• Bypass may not be possible
• Preservation of recipient IVC needed
• Use “piggy-back technique”

→ Donor liver attached directly to patient’s IVC

BILLIARY TRACT

Biliary Tract — 20% that gives 80%

1. Main Components (must-remember)

• Right & Left hepatic ducts → drain liver lobes.
• They join to form the Common Hepatic Duct (CHD).
• Cystic duct from gallbladder joins CHD → forms Common Bile Duct (CBD).
• These lie in the free edge of the lesser omentum (hepatoduodenal ligament).

2. Key Anatomical Relationships (exam gold)

Hepatic ducts

• Confluence of right + left hepatic ducts = surgically accessible point (you can see it without entering liver tissue).
• Left hepatic duct sometimes runs along quadrate lobe base → partly outside liver → important variant.

Common Hepatic Duct (CHD)

• Formed near right end of porta hepatis.
• Descends between two layers of lesser omentum.
• Lies closely applied to porta hepatis at rest, but separates when liver is lifted in surgery.

Cystic duct

• Joins CHD on right side at an acute angle → classic orientation.
• Joining point = beginning of CBD.

3. Why Surgeons Care (super high-yield)

• Identifying the confluence of hepatic ducts is critical → avoid injury during cholecystectomy.
• Understanding that the ducts lie within the lesser omentum helps surgeons orient safely.
• Left hepatic duct being partly extrahepatic sometimes → vulnerable during hilar dissection.

4. Fast Diagram in Words (memory trick)

R hepatic duct \
                 → Common Hepatic Duct → + cystic duct → CBD
L hepatic duct /

5. Absolute must-remember lines

• Right + left hepatic ducts → CHD
• CHD + cystic duct → CBD
• All lie in the free edge of lesser omentum
• Confluence is the only reliably accessible site without entering liver
• Left hepatic duct may lie partly outside liver (variant)

Gallbladder — 20% that gives 80%

1. Function (must-remember)

• Stores & concentrates bile produced by the liver.
• Capacity ≈ 50 mL.

2. Parts (very high yield)

• Fundus
• Body
• Neck → cystic duct

3. Location & Surface Marking (exam gold)

Fundus

• Lies in the gallbladder fossa on visceral surface of right lobe of liver (near quadrate lobe).
• Surface landmark → tip of right 9th costal cartilage, where:
• Transpyloric plane meets right costal margin
• This is where tenderness is felt in gallbladder disease.
• Fundus usually lies on:
• Transverse colon (beginning)
• Just left of the hepatic flexure

Body

• Runs backwards & upwards toward porta hepatis
• Contacts first part of duodenum

Neck

• Higher than the fundus (unless liver is retracted).
• Continues as the cystic duct.

4. Cystic Duct — Critical for exams & surgery

• Length: 2–3 cm
• Diameter: 2–3 mm
• Runs backwards, downwards, and to the left to join CHD → forms CBD.
• Usually passes in front of the right hepatic artery.

Hartmann's Pouch

• Small diverticulum at the neck.
• Always pathological, often where gallstones get impacted.

5. Attachments & Surgical Importance

• Gallbladder is firmly bound to liver undersurface by connective tissue.
• Cystic veins drain directly into the liver → bleeding risk.
• Small accessory bile ducts may run from liver to gallbladder:
• If missed during cholecystectomy → bile leak into peritoneum.

6. Peritoneal Variations (clinically relevant)

• Usually covered smoothly by liver peritoneum.
• Variants:
• Gallbladder on a mesentery → risk of torsion.
• Embedded within liver.
• Absent gallbladder (rare).

7. Common Congenital Variations (super high-yield)

• Phrygian cap — folded fundus (most common).
• Duplication — two gallbladders ± two cystic ducts.
• Septate gallbladder — divided lumen.

Gallbladder Blood Supply

1. Arterial Supply (Exam GOLD ⭐)

Cystic artery

• Usually from the right hepatic artery (MOST COMMON).
• Runs through Calot’s triangle, which is bordered by:
• Common hepatic duct
• Cystic duct
• Inferior surface of liver
• Supplies the neck → body → fundus.

Important variations (very exam-worthy)

• May arise from:
• Main hepatic artery
• Left hepatic artery
• Gastroduodenal artery
• May pass in front of cystic duct or bile duct → surgical injury risk.

2. Venous Drainage (Simple but high yield)

• NO major cystic vein accompanies cystic artery (important surgical fact).
• Most venous drainage:

→ Multiple small veins in gallbladder bed

→ Directly into liver parenchyma

→ Then hepatic veins.

• Occasionally:
• 1–2 cystic veins drain into right portal vein (rare).

3. Lymphatic Drainage (Must-memorize pathway)

Primary drainage

• Cystic node (in Calot’s triangle near junction of CHD + cystic duct)
• Nodes in porta hepatis
• Node at anterior boundary of epiploic foramen

Final drainage

• Coeliac preaortic lymph nodes

(same final destination as most upper abdominal organs)

Gallbladder Structure — 20% That Gives 80%

1. Wall Structure (very high yield)

• Gallbladder = fibromuscular sac.
• Surprisingly little smooth muscle (important distinction from GIT).
• Mucosa:
• Lined by simple columnar epithelium.
• Actively absorbs water + solutes → concentrates bile.
• No goblet cells.
• Mucous glands only in the neck.

2. Internal Folds (exam gold)

• In the body → mucosa forms honeycomb folds.
• In the neck + cystic duct → mucosa forms spiral folds:
• Called the Spiral Valve of Heister.
• Function: maintains patency, slows bile flow.

Common Hepatic Duct — High-Yield Essentials

3. Formation

• Right + Left hepatic ducts unite near right margin of porta hepatis.
• Union forms Common Hepatic Duct (CHD) — Y-shaped.

4. Joining with Cystic Duct

• Cystic duct joins CHD after about 3 cm → forms Common Bile Duct (CBD).
• Union typically occurs on the right side of the CHD, 1–2 cm above duodenum.

5. Surgical Relationships (super exam high-yield)

Right Hepatic Artery

• Normally runs behind CHD.
• But sometimes may run in front → risk during cholecystectomy.

6. Important Anomalies (major exam questions)

Cystic duct variations

• May run parallel to CHD for a long distance before joining.
• May spiral behind CHD and join it on the left side.
• Cystic duct may be absent → gallbladder drains directly into CHD.

Accessory ducts

• Accessory right hepatic duct may drain into:
• CHD
• Cystic duct
• Gallbladder

→ Major cause of bile leak if unrecognized.

Bile Duct — 20% That Gives 80%

1. Basic Facts (must-memorize)

• Length: 6–8 cm
• Diameter: ≤ 8 mm (normal)
• Formed by: Common hepatic duct + cystic duct
• Drains bile → duodenum (2nd part)

2. Three Parts (Super Exam High-Yield)

A. Upper third — Supraduodenal

• Location: Free edge of lesser omentum
• Orientation:
• In front of portal vein
• To the right of hepatic artery
• Why important: Most accessible part in surgery
• Boundary relation: forms anterior boundary of epiploic foramen

B. Middle third — Retroduodenal

• Runs behind the 1st part of duodenum
• Slopes down + right
• Key relations:
• Portal vein now lies to its left
• Gastroduodenal artery also on the left
• IVC lies behind it

C. Lower third — Paraduodenal / Pancreatic

• Slopes further to the right, runs in a groove on the posterior surface of pancreatic head
• Sometimes embedded inside pancreatic tissue
• Why important: Pancreatic head cancers commonly obstruct the bile duct here

3. Terminal Anatomy (Very High Yield)

Union with pancreatic duct

• Joins at ~60° angle → forms Hepatopancreatic ampulla (Ampulla of Vater)

Sphincters

Surrounded by:

1. Sphincter of bile duct
2. Sphincter of pancreatic duct
3. Sphincter of ampulla (Oddi)

• Sometimes pancreatic + ampullary sphincters absent → only bile duct sphincter present.

Opening site

• Opens into posteromedial wall of 2nd part of duodenum
• At the Major duodenal papilla, 10 cm distal to pylorus

Blood Supply — 20% That Gives 80%

1. Arterial Supply (Exam GOLD)

Extrahepatic biliary tract receives small arterial branches from:

1. Cystic artery
2. Right hepatic artery
3. Posterior branch of the superior pancreaticoduodenal artery

These branches form anastomotic channels along the duct → important for surgical safety and healing.

2. Venous Drainage

• Small veins drain directly → portal vein
• Some enter liver substance first

(Important because bleeding can track into liver during surgery.)

Nerve Supply — 20% That Gives 80%

3. Parasympathetic (Vagal)

• Comes mainly from hepatic branch of the anterior vagal trunk
• Function:
• Contract gallbladder
• Relax ampullary sphincter (Oddi)
• BUT neural control is less important than hormonal CCK.

4. Sympathetic

• Preganglionic from T7–T9 (lateral horn)
• Synapse in coeliac ganglia
• Function:
• Inhibit gallbladder contraction

5. Pain Fibres (Very high yield)

• Afferents run mainly with right sympathetic fibres → T7–T9 segments
• Some fibres from gallbladder travel via right phrenic nerve (C3–C5)

→ because of connections with coeliac plexus.

6. Pain Patterns (Extremely Exam-Relevant)

Typical biliary pain

• Right hypochondrium
• Epigastrium
• May radiate:
• Around to back (infrascapular region) → T7–T9 dermatomes

Referred pain (phrenic nerve)

• Right shoulder tip pain
• Due to phrenic nerve C3–C5 involvement

Biliary Tract Imaging

1. Ultrasound (US) — First-line test (Exam GOLD ⭐)

• Best initial investigation for gallbladder & bile ducts.
• Shows:
• Gallstones
• Gallbladder wall thickening
• Common bile duct dilation
• Pericholecystic fluid
• Has replaced old oral/IV contrast cholangiography that relied on liver-excreted radiopaque dyes.

2. ERCP — Endoscopic Retrograde Cholangiopancreatography

• Combines endoscopy + fluoroscopy.
• Procedure:
• Endoscope placed → duodenum
• Catheter inserted into ampulla of Vater
• Contrast injected → ducts become visible on X-ray
• Uses:
• Visualize bile duct + pancreatic duct
• Therapeutic: remove stones, stent strictures, sphincterotomy
• Invasive → risk of pancreatitis

Not first choice for diagnosis anymore.

3. MRCP — Magnetic Resonance Cholangiopancreatography

• Non-invasive MRI technique for biliary & pancreatic ducts.
• No contrast injection into ducts.
• Shows:
• Stones
• Strictures
• Dilated ducts
• Pancreatic duct anomalies
• Often replaces ERCP for diagnosis.

Portal Vein — 20% That Gives 80%

1. Formation (EXAM GOLD ⭐)

• Formed by superior mesenteric vein + splenic vein
• Union occurs behind the neck of the pancreas
• From this point SMV becomes the portal vein

2. Course (Very High Yield)

Behind pancreas & 1st part of duodenum

• Portal vein lies:
• In front of IVC
• Behind the pancreas & first part of duodenum

Then enters lesser omentum

• Loses contact with IVC as it enters between the two layers of the lesser omentum.

In free edge of lesser omentum

• Runs vertically upward
• Lies behind bile duct
• Lies behind hepatic artery
• Forms posterior boundary of the portal triad in the hepatoduodenal ligament

At porta hepatis

• Divides into right & left portal veins → supplying each half of the liver.

3. Tributaries (Easy Marks)

Portal vein receives:

• Right & left gastric veins
• Superior pancreaticoduodenal vein
• Cystic veins (if present) → join right portal branch
• Paraumbilical veins → join left portal branch

(Run with ligamentum teres)

4. Ligamentum Teres (High Yield Clinical Pearl)

• Remnant of left umbilical vein
• Not fully fibrosed in 50% of adults
• Can be cannulated at the umbilicus → access to portal system.

5. Important Characteristics

• Length ≈ 8 cm
• NO valves in portal vein or tributaries (after early infancy)

6. Portal–Systemic Anastomoses (Always in Exams)

Five key sites:

1. Lower esophagus
2. Upper anal canal
3. Bare area of liver
4. Periumbilical region (caput medusae)
5. Retroperitoneal areas

7. Portal Hypertension (Super High Yield Clinically)

• Up to 80% of portal blood can be diverted to collaterals
• BUT collaterals do NOT reduce portal pressure

→ Why variceal bleeding remains a risk.