Liver Anatomy

Liver And Extrahepatic Biliary Apparatus

Question 1. Describe the Liver under the following headings:

1. Liver Introduction
2. Liver External features
3. Liver Relations
4. Liver Lobes
5. Liver Hepatic segments
6. Liver Blood supply
7. Liver Venous drainage
8. Liver Development
9. Liver Histology and
10. Liver Applied anatomy.

1. Liver Introduction:

The liver is a large wedge–shaped solid organ present in the right upper quadrant of the abdomen and occupies the whole of the right hypochondrium, the greater part of the epigastrium, and part of the left hypochondrium.

• Weight = 1600 g in males and 1300 g in females.
• Color = Reddish brown.

Read And Learn More: Anatomy Question And Answers

2. Liver External features:

Two surfaces:

• Diaphragmatic surface: It is convex and further divided into 4 surfaces:
  • Superior
  • Anterior
  • Posterior
  • Right lateral
• Visceral surface: It is slightly concave and presents:
  • Fossa for gall bladder
  • Fissure for ligamentum venosum
  • Porta hepatis

One border:

• Inferior border: It presents a cystic notch and notch for ligamentum teres/interlobar notch.

3. Liver Relations:

1. Superior surface: It is related to:
   • Heart
   • Domes of diaphragm
2. Anterior surface: It is related to:
   • Xiphoid process
   • Anterior abdominal wall
   • Diaphragm
3. Right lateral surface: It extends from the 7th to 10th ribs. Its relations are as follows:
   • Upper 1/3rd is related to the diaphragm, pleura and lung.
   • Middle 1/3rd is related to, the diaphragm and costodiaphragmatic recess.
   • The lower 1/3rd is related to the diaphragm only.
4. Posterior surface: It is related to:
   • Right suprarenal gland
   • Inferior vena cava
   • Esophagus
5. Inferior surface:
   • The left lobe is related to tuber omental and stomach.
   • The right lobe is related to the pylorus of the stomach, gall bladder, 2nd part of the duodenum and right kidney.

4. Liver Lobe:

They are described as anatomical lobes and physiological lobes.

Anatomical lobes:

The liver is divided into two anatomical lobes as under:

• On the anterosuperior surface, by the attachment of falciform ligament.
• On the visceral surface, by ligamentum teres (inferiorly) and fissure for ligamentum venosum (superiorly).

Note: The right lobe is larger and forms 5/6th of the liver. It presents the caudate and quadrate lobes on its visceral surface.

• Caudate lobe between the groove for inferior vena cava and fissure for ligamentum venosum.
• Quadrate lobe below the porta hepatis between fossa for gall bladder and fissure for ligament teres.

Physiological lobes/true lobes:

The liver is divided into two physiological lobes by an imaginary sagittal plane called the Cantlie plane.

• On the anterosuperior surface, it passes from the groove for the inferior vena cava to the cystic notch.
• On the posteroinferior surface, it passes from the fossa for the gall bladder to the groove for the inferior vena cava and bisects the caudate lobe into two halves.

5. Liver Hepatic segments:

There are 8 hepatic segments:

• The right true lobe is subdivided into anterior and posterior parts.
• The left true lobe is subdivided into medial and lateral parts.

Each of the above four parts is further subdivided into upper and lower parts to form 8 hepatic segments.

The hepatic segments thus formed are shown in the box given below:

6. Liver Blood Supply:

• 20% of its blood supply from the hepatic artery.
• 80% of its blood supply from the portal vein.

7. Liver Venous drainage:

• Blood from the hepatic sinusoid is drained into interlobular veins, which join to form sublobular veins.
• The sublobular veins join to form hepatic veins, which drain into the inferior vena cava.

8. Liver Development:

• The liver develops in the 4th week of intrauterine life from the following sources:
• The Parenchyma of the liver develops from the endodermal hepatic bud.
• Stroma and Kupffer cells of the liver develop from the mesoderm of the septum transversum.
• Sinusoids of liver develop from broken vitelline and umbilical veins.

Note:

• The hepatic bud arises from the endodermal lining of the caudal end of the foregut.
• It grows cranially and gives rise to a small bud on the right side called pars cystic.
• The main part of the bud is now called pars hepatica.
• Pars cystic gives rise to the gall bladder and pars hepatica to the parenchyma of the liver.

9. Liver Histology:

A section through the liver presents the following histological features:

Classical hexagonal lobules:

These are separated from each other by connective tissue.

• Each lobule contains a central vein.
• Each lobule consists of anastomosing cords of hepatocytes radiating away from central vein.
• The spaces between the cords of hepatocytes are called sinusoids.

Portal triads/tracts:

• At each corner of the lobule, a triangular area of connective tissue contains:
• A branch of the portal vein (portal venule)
• A branch of the hepatic artery (hepatic arteriole)
• Interlobular bile duct (hepatic ductule)

Kupffer cells: They are phagocytic cells found in the wall of sinusoids.

Note: Functional units of the liver

• Portal lobule: A triangular area of the liver parenchyma enclosed by the lines connecting three adjacent central veins. It includes portions of 3 classical lobules with a portal triad in the center.
• Hepatic acinus: A diamond–shaped area of the liver parenchyma enclosed by the lines joining two adjacent central veins and two portal triads.

10. Liver Applied Anatomy:

• Hepatitis: It is the inflammation of the liver, which is usually of viral origin. It manifests as jaundice and loss of appetite.
• Cirrhosis of the liver: It is the fibrosis of liver parenchyma by the proliferation of perilobular connective tissue to replace necrosed hepatocytes. The necrosis of hepatocytes usually occurs due to high intake of alcohol. Clinically, it manifests as shrinkage of liver jaundice and portal hypertension.

Question 2. Write a short note on the bare area of the liver. Give its clinical significance. 
Answer:

• Bare Area Of The Liver is a triangular area on the posterior aspect of the right lobe of the liver.
• Bare Area Of The Liver is so-called because it is not covered by the peritoneum.
• Bare Area Of The Liver lies between the two layers of the right coronary ligament.
• Bare Area Of The Liver is in direct contact with the right dome of the diaphragm.
• Bare Area Of The Liver inferomedial part is related to the right suprarenal gland.

Liver Clinical Significance:

• The bare area and two layers of the right coronary ligament enclose right extraperitoneal subphrenic space.
• In an amoebic liver abscess, pus may collect in this space to form a subphrenic abscess which may even rupture into the right pleural cavity through right dome of diaphragm.

Question 3. Give the visceral realtions of the liver.
Answer:

Visceral relations of the liver:

These are relations on the posteroinferior surface of the liver. This surface of the liver presents a groove for IVC, fossa for gall bladder, porta hepatis, and groove for ligamentum venosum and ligamentum teres hepatitis. It is demarcated by grooves for ligamentum venosum and ligamentum teres into the right and left lobes. The right lobe presents two more lobes on this surface, viz. caudate lobe and quadrate lobe.

The posterior surface of the right lobe presents:

• Bare area of the liver, which is related to the right suprarenal gland in its inferomedial part and diaphragm.
• Groove for inferior vena cava, lodging this vein.

The posterior surface of the left lobe:  The left lobe of the liver is related to the abdominal part of the esophagus – causing an esophageal impression.

The inferior surface of the left lobe: The inferior surface of the left lobe is related to tuber omental and presents a large concave gastric impression.

The inferior surface of the right lobe:  Right lobe presents the fossa of the gall bladder.

• The quadrate lobe is related to the pylorus and the first part of the duodenum.
• The inferior surface of the right lobe, right to the fossa for the gall bladder, is related to:
  • 2nd part of duodenum – causing duodenal impression.
  • Right colic (hepatic) flexure of the colon – causing colic impression.
  • Right kidney – causing renal impression.

Question 4. Enumerate the factors responsible for the fixation of the liver.
Answer:

• Hepatic veins that connect it to the IVC
• Lesser omentum that connects it to the stomach
• The falciform ligament that connects it to the diaphragm
• Coronary and the 2 triangular ligaments (right and left) which connect it to the diaphragm
• Ligamentum venosum that connects the left branch of the portal vein to the IVC
• Ligamentum teres that connects the left branch of the portal vein to the anterior abdominal wall at the umbilicus
• The pressure of the related organs

 

Question 6. Write a short note on the cystohepatic triangle of Calot. 
Answer:

Cystohepatic triangle Boundaries:

• Above: Inferior surface of the liver.
• Left side: Common hepatic duct.
• Right side: Cystic duct.

Cystohepatic triangle Contents:

• Cystic lymph node (of Lund) in the angle between cystic and common hepatic ducts.
• The cystic artery is a branch from the right branch of the hepatic artery.

Cystohepatic triangle Applied anatomy:

Moynihan’s hump:

It is a dangerous anomaly in which the cystic artery is short and right hepatic artery takes a tortuous course/caterpillar-like turn, which may be cut inadvertently during cholecystectomy and cause profuse bleeding.

Question 7. Give the anatomical basis of the referred pain of the gall bladder.
Answer:

The gall bladder pain is referred to as:

1. Epigastrium
2. Tip of right shoulder and
3. Inferior angle of right scapula.

Anatomical basis:

1. Pain is referred to as epigastrium through parasympathetic fibers (vagus nerve).
2. Pain is referred to the tip of the right shoulder through the phrenic nerve (C3, 4, 5) if there is irritation of the diaphragm.
3. Pain is referred to the inferior angle of the right scapula through sympathetic fibers derived from T7 spinal segment.

Question 8. Write a short note on the microscopic/histological structure of gall bladder.
Answer:

The gall bladder wall consists of the following layers:

1. Mucosa: It is thrown into temporary folds (rugae) which disappear when the gall bladder is distended with bile.

It consists of only two layers, i.e. epithelium and lamina propria, because muscularis mucosae is absent.

1. Lining epithelium: Mucous membrane is lined by tall columnar epithelium with a brush border.
2. Lamina propria: Lamina propria is made up of loose connective tissue with diffuse lymphocytes and sections of folded epithelium.

2. Fibromuscular coat: It is made up of smooth muscle fibers running in various directions with loose areolar tissue rich in elastic fibers interspersed between muscle fibers.

3. Serosa or adventitia: Serosa is a thin layer of mesothelium and adventitia is a thin layer of connective tissue.