Chemicals Liberated by the Endocrine Part

And so on.

The liver is an indispensable gland of the body.

1. Metabolism of carbohydrates, fats and proteins.
2. Synthesis of bile and prothrombin.
3. Excretion of:
   • Drugs
   • Toxins
   • Poisons
   • Cholesterol
   • Bile pigments
   • Heavy metals
4. Protective functions by:
   • Conjugation
   • Destruction
   • Phagocytosis
   • Antibody formation
   • Excretion
5. Storage of:
   • Glycogen
   • Iron
   • Fat
   • Vitamins A and D

The liver occupies:

Colour and Consistency

Weight

Proportional Weight

Hold the liver in such a way that:

1. Groove for the inferior vena cava on the posterior surface of liver should be vertically straight.
2. Broad base of the wedge-shaped liver is on the right.
3. Smooth convexo-concavo-convex surface faces upwards.

It Has

The liver has five surfaces:

Inferior Border

• The inferior border is sharp anteriorly, where it separates the anterior surface from the inferior surface.
• It is somewhat rounded laterally, where it separates the right surface from the inferior surface.
• The sharp anterior part is marked by:
  1. Interlobar notch / notch for ligamentum teres
  2. Cystic notch for the fundus of the gallbladder
• In the epigastrium, the inferior border extends from the left 8th costal cartilage to the right 9th costal cartilage.

The lobes of liver are defined into two types:

Anatomical Lobes

The liver is divided into right and left lobes:

• Anteriorly and superiorly → by attachment of falciform ligament.
• Inferiorly and posteriorly → by fissures for:
  • Ligamentum teres
  • Ligamentum venosum

Right Lobe

• It is six times larger than the left lobe.
• It has two more lobes:
• Caudate lobe
• Quadrate lobe

Caudate Lobe — Spiegel’s Lobe

Processes

1. Caudate process
   • Connects right lobe and caudate lobe.
2. Papillary process
   • Rounded elevation on the inferior and left part of caudate lobe.

Quadrate Lobe

• Quadrangular in shape.
• Situated on the inferior surface.
• Lies between:
• Fossa for gallbladder
• Fissure for ligamentum teres hepatis
• Extends from the inferior border of liver to porta hepatis.

Left Lobe

• Forms one-sixth of the liver.
• Much smaller than the right lobe.
• It is flattened from above.
• It shows tuber omentale:
• Rounded elevation on the inferior surface of the left lobe.
• Comes in contact with the lesser omentum.

Physiological Right and Left Lobes

Most of the liver is covered by peritoneum.

Areas Not Covered by Peritoneum

Bare Area — Boundaries

The liver is supported by false and true ligaments.

A. False Ligaments

1. Falciform Ligament

• Sickle-shaped peritoneal fold.
• Connects the liver with:
• Diaphragm
• Anterior abdominal wall
• Up to the umbilicus
• It develops from the ventral mesogastrium.

Contents

• Ligamentum teres
• Paraumbilical vein
• Tributary of portal vein
• Accessory portal system of Sappey
• Communicates paraumbilical vein with diaphragmatic veins.

2. Coronary Ligament

• Triangular fold of peritoneum.
• Connects the bare area of liver with diaphragm.
• Consists of two layers:

On the Right

Both layers fuse to form the right triangular ligament.

On the Left

• Upper layer is continuous with the right layers of the falciform ligament.
• Lower layer is continuous with the peritoneal reflection along the right border of the caudate lobe.

Contents

• Connective tissue
• Branches of the right phrenic artery

3. Right Triangular Ligament

• Small triangular fold of peritoneum.
• Connects the right lobe of liver to diaphragm.
• Encloses the apex of the bare area of liver.

4. Left Triangular Ligament

• Small triangular fold.
• Connects the superior surface of left lobe of liver to diaphragm.
• Has:
• Upper layer
• Lower layer

On the Left

Both layers are continuous to form a free margin.

On the Right

• Upper layer is continuous with the left layer of the falciform ligament.
• Lower layer is continuous with the anterior layer of lesser omentum along the fissure for ligamentum venosum.

5. Lesser Omentum

• Fold of peritoneum that connects the lesser curvature of stomach and proximal part of duodenum to the liver.
• It is L-shaped, with the vertical limb attached to the margins of porta hepatis.

Contents

Along the lesser curvature of stomach:

• Anastomosis of right and left gastric vessels
• Branches of gastric nerves

Within the free margin:

• Portal vein
• Bile duct
• Hepatic artery
• Hepatic plexus of nerves and lymphatics

B. True Ligaments

1. Ligamentum Teres Hepatis

• Remnant of the obliterated left umbilical vein.
• Extends from the umbilicus to the left branch of portal vein.
• Passes along the free margin of the falciform ligament.

2. Ligamentum Venosum

• Remnant of the obliterated ductus venosus.
• In foetal life, it connects the left branch of portal vein with inferior vena cava.
• It bypasses the hepatic circulation.

1. Anterior Surface

• Triangular and slightly convex.
• Related to:
1. Xiphoid process and anterior abdominal wall in the median plane.
2. Diaphragm on each side.
• Falciform ligament is attached to the anterior surface a little to the right of the median plane.

2. Superior Surface

• Quadrilateral.
• Shows a concavity in the middle.
• This is the cardiac impression.
• On each side of the impression, the surface is convex to fit the dome of the diaphragm.
• The diaphragm separates this surface from:
  • Pericardium and heart in the middle
  • Pleura and lung on each side

3. Right Surface

• Quadrilateral and convex.
• Related to the diaphragm opposite the 7th to 11th ribs in the midaxillary line.

4. Posterior Surface

• Triangular.
• Middle part shows a deep concavity for the vertebral column.
• Related to:

1. Bare Area of Liver

Related to diaphragm.

2. Groove for Inferior Vena Cava

• Lodges the inferior vena cava.
• Its floor is pierced by the hepatic veins.

3. Caudate Lobe

Related to the superior recess of lesser sac.

4. Fissure for Ligamentum Venosum

• Very deep.
• Extends to the front of the caudate lobe.
• Contains two layers of the lesser omentum.
• Ligamentum venosum lies on its floor.
• Ligamentum venosum is a remnant of the ductus venosus of foetal life.
• Connected below to the left branch of portal vein.
• Connected above to the inferior vena cava.

5. Oesophageal Impression

On posterior surface of the left lobe.

5. Inferior Surface

• Quadrilateral.
• Directed downwards, backwards and to the left.
• Marked by impressions for neighbouring viscera.

1. Gastric Impression

Shallow impression on the inferior surface of the left lobe of liver.

2. Tuber Omentale

• Rounded elevation.
• Comes in contact with lesser omentum.

3. Fissure for Ligamentum Teres

4. Quadrate Lobe

Related to:

• Pyloric end of stomach
• First part of duodenum

5. Fossa for Gallbladder

Lodges the gallbladder.

6. Colic Impression

Related to right colic flexure.

7. Duodenal Impression

Superior duodenal flexure [junction of 1st and 2nd part] is related to:

• Upper part of fossa for gallbladder
• Adjoining part of right lobe

8. Renal Impression

• Part of inferior surface posterior to the colic impression.
• Related to right kidney.

9. Right Suprarenal Impression

Mnemonic — DAV

Structures at porta hepatis from anterior to posterior.

The liver has dual blood supply:

Distribution within Liver

• Before entering the liver:
  • Hepatic artery divides into right and left branches.
  • Portal vein divides into right and left branches.
• Within the liver:
  • They redivide to form segmental vessels.
  • These further divide to form interlobular vessels.
  • Interlobular vessels run in the portal canals.
  • Further ramifications of interlobular branches open into the hepatic sinusoids.
  • Hepatic arterial blood mixes with portal venous blood in the sinusoids.
  • There are no anastomoses between adjoining hepatic arterial territories.
  • Hence, each branch is an end artery.

• Hepatic sinusoids drain into interlobular veins.
• Interlobular veins join to form sublobular veins.
• Sublobular veins unite to form hepatic veins.
• Hepatic veins drain directly into the inferior vena cava.
• Hepatic veins do not have an extrahepatic course.
• They open directly into the inferior vena cava.
• These veins provide great support to the liver, besides the intra-abdominal pressure.

Groups of Hepatic Veins

The hepatic veins are arranged in three groups:

• Middle hepatic vein lies in the sagittal plane that divides the liver into right and left lobes.
• Left hepatic vein lies between medial and lateral segments of left true lobe.
• Middle hepatic vein lies between anatomical right and left lobes.
• Right hepatic vein lies between anterior and posterior segments of right true lobe.

1. Superficial Lymphatics

• Run on the surface of the liver, beneath the peritoneum.
• Terminate in:
• Caval nodes
• Hepatic nodes
• Paracardial nodes
• Coeliac nodes

2. Deep Lymphatics

• Drain partly into the nodes around the inferior vena cava.
• Partly into the hepatic nodes.

The liver is supplied by:

1. Sympathetic Fibres

• Derived from the coeliac plexus.
• Run along the vessels in the free margin of lesser omentum.
• Enter the porta hepatis.

2. Parasympathetic Fibres

Derived from the hepatic branch of the anterior vagal trunk.

3. Pain Sensation

Cantlie’s Plane

Divides the right and left physiological lobes.

On the anterosuperior surface, it passes along the line joining:

• Cystic notch
• Groove for inferior vena cava

On the inferior surface, the plane passes through the fossa for gallbladder.

On the posterior surface, the plane passes through the middle of the caudate lobe.

Eight Segments