anatomyphysiologyblog - Hepatobiliary Apparatus: Gross Anatomy of Liver together with Gallbladder

Hepatobiliary System

Liver

The liver is the largest of the abdominal viscera together with occupies a substantial part of the upper abdominal cavity. It is an essential organ that performs a broad make of metabolic activities required for homeostasis, nutrition together with immunity. It is mainly composed of epithelial cells (hepatocytes) originating from the endoderm of primitive foregut. These cells are bathed inward blood derived from the hepatic portal veins together with hepatic arteries, thereby facilitating continuous chemic telephone commutation betwixt the cells together with the blood. Hepatocytes are too associated amongst an extensive organization of infinitesimal canals, which cast the biliary organization into which products are secreted.

The liver essentially has the next functions:

removes together with breaks downward of toxic, or potentially toxic, materials from the blood
regulates blood glucose together with lipids,
stores of for sure vitamins, iron, together with other micronutrients
breaks downward or modification of amino acids
provides thermal release energy to body peculiarly at rest
removes particulates from the blood flow past times phagocytic macrophages
acts every bit organ of hemopoiesis inward fetal life

Location together with Shape of the Liver

The liver is located inward the upper component of the abdominal cavity merely beneath the diaphragm. The greater component of the liver is situated nether comprehend of the correct costal margin together with too extends to the left to attain the left hemidiaphragm. The diaphragm separates liver from pleura, lungs, pericardium together with heart. Thus it occupies most of the correct hypochondrium together with epigastrium together with too a modest part extends into the left hypochondrium.

Click here to persuasion the 3D icon of liver from http://www.healthline.com/

The liver has an overall wedge shape, which is inward component determined past times the cast of the upper abdominal cavity into which it grows. For example, the superior together with correct lateral aspects are shaped past times the anterolateral abdominal together with breast wall every bit good every bit the diaphragm whereas the inferior facial expression is shaped past times the side past times side viscera.

It is covered past times liver capsule which plays an of import component inward maintaining the integrity of its shape. Once the capsule is lacerated, the liver tissue is easily parted. This, inward combination amongst its high vascular supply, makes the liver prone to potentially lethal injuries if it is split open.

Presenting parts of Liver

Surfaces

Superior surface: Features together with Relations

It is the largest surface, convex inward shape together with is molded to the undersurface of the domes of the diaphragm. This surface is covered past times peritoneum except for a modest triangular expanse betwixt the ii diverging layers of falciform ligament. The bulk of the superior surface lies beneath the correct dome (related to the correct diaphragmatic pleura together with base of operations of the correct lung). Centrally at that topographic point is a shallow cardiac impression corresponding to the seat of the pump inward a higher identify the key tendon of the diaphragm together with is related to the pericardium. The left side of the superior surface lies beneath component of the left dome of the diaphragm together with is related to component of the left diaphragmatic pleura together with base of operations of the left lung.

Anterior surface: Features together with Relations

Triangular together with convex inward shape, the anterior surface is covered past times peritoneum except at the attachment of the falciform ligament. Much of it is inward contact amongst the anterior attachment of the diaphragm. Separated past times the diaphragm, the anterior surface is related on the correct amongst the pleura together with 6^th to 10^th ribs together with their cartilages together with amongst 7^th together with 8^th costal cartilages on the left. The medline expanse of the anterior surface lies behind the xiphoid procedure together with the anterior abdominal wall inward the infracostal angle.

Right Surface: Features together with Relations

Covered past times peritoneum, the correct surface lies side past times side to the correct dome of the diaphragm which separates it from the correct lung together with pleura together with the 7th to eleventh ribs. The correct lung together with basal pleura betwixt the diaphragm together with the 7th together with 8th ribs prevarication inward a higher identify together with lateral to upper 3rd of this surface. The diaphragm, the costodiaphragmatic recess, together with the 9th together with 10th ribs are related lateral to the middle 3rd of the correct surface. In the lower third, the diaphragm together with thoracic wall are inward conduct contact.

The superior, anterior together with correct surfaces are collectively referred every bit diaphragmatic surface.

Posterior surface

The posterior surface is convex, broad on the right, but narrow on the left. Much of the posterior surface is attached to the diaphragm past times loose connector tissue inward the part of the 'bare area'.

Features together with relations:

From the left to the right

The posterior surface over the left lobe presents a shallow oesophageal impression which is related to the abdominal component of the oesophagus. The posterior surface of the left lobe to the left of this impression is related to component of the fundus of the stomach.

A deep median concavity close the attachment of ligamentum venosum is related to vertebral column.

Fissure for ligamentum venosusm separates the caudate lobe of liver from the left lobe. The lips of the crack give attachment to the ii layers of the lesser omentum. The flooring of the crack lodges the ligamentum venosum.

Caudate lobe (explained later)

Groove for inferior venacava lies inward the medial goal of the ‘bare area’ together with to the left it is related to the caudate lobe. The groove lodges the inferior venecava.

The ‘bare area’ of the liver is devoid of peritoneum together with is connected to the diaphragm past times loose areolar tissue. Inferolateral angle of the 'bare area' presents suprarenal impression that is related amongst the upper pole of the correct suprarenal gland.
Inferior Surface

Inferior surface

The inferior surface is irregular together with bounded separated from the anterior together with correct surface past times inferior border.

Features together with Relations:

The inferior surface of the left lobe of liver presents gastric impression which is related inferiorly amongst the fundus of tummy together with upper lesser omentum.

Fissure for ligamentum teres lodges the ligamentum teres.

Quadrate lobe (explained later) is related to pylorus, showtime component of duodenum together with lower component of lesser omentum.

Fossa for gallbladder lodges the gallbladder.

To the correct of the fossa for the gall bladder, inferior surface of liver is related amongst the showtime component of duodenum, the hepatic flexure of colon, the correct kidney together with correct suprarenal gland.

The posterior together with inferior surfaces are together called poeteroinferior surface or visceral surface of the liver.

Porta Hepatis:

The porta hepatis is hilum of the liver introduce inward the inferior surface. It provides a passageway to the neurovascular together with biliary structures, except the hepatic veins. It is anteriorly bounded past times the quadrate lobe together with the caudate procedure posteriorly. The portal vein, hepatic artery together with hepatic nervous plexus ascend into the parenchyma of the liver. The correct together with left hepatic bile ducts together with some lymph vessels emerge from it. At the porta hepatis, the hepatic ducts, the hepatic artery amongst its branches together with the portal vein are arranged inward that monastic state from earlier backwards. The margin of porta gives attachment to the lesser omentum.

Lobes

Liver has a larger right and smaller left ‘anatomical’ lobes. The work of attachment of falciform ligament on anterior together with superior surfaces of liver together with the crack for ligamentus venosum together with crack for ligamentum teres on the posteroinferior surface of the liver separate the ii lobes.

The correct lobe too presents quadrate lobe together with caudate lobe.

Right Lobe

The correct lobe is largest together with contributes to all surfaces.

The work of attachment of the falciform ligament, the crack for the ligamentum teres, the groove for the ligamentum venosum, together with the attachment of the lesser omentum separate it from the left lobe.

The inferior border of the correct lobe, to the correct of the gallbladder, may introduce a bulge of tissue, which when pronounced, is referred to every bit Riedel's lobe.

Quadrate lobe

Present inward the inferior surface

Anatomically is the component of correct lobe together with functionally belongs to left lobe

Boundaries

Anteriorly – inferior border of the liver

Posteriorly – porta hepatis

To the correct – fossa for the gallbladder

To the left – crack for ligamentum teres

Relations:

Pylorus together with showtime component of duodenum

Caudate lobe

Present inward the posterior surface of the liver

Anatomically is the component of correct lobe together with functionally belongs to left lobe

Boundaries

Above continuous amongst superior surface

Below porta hepatis

To the correct groove for inferior vencava

To the left crack for ligamentum venosum

Caudate process: Below together with to the right, caudate lobe introduce a narrow strip called the caudate process. Caudate procedure bounds porta hepatis posteriorly together with forms the upper boundary of epiploic foramen.

Left lobe

The left lobe is smaller together with ends inward a sparse apex pointing into the left upper quadrant. Since it is substantially thinner than the correct lobe it is to a greater extent than flexible.

Functional lobes together with segments of the liver

The functional correct together with left lobes of the liver are separated past times an imaginary bird passing along the flooring of fossa for gall bladder together with the groove for inferior venacava (cholecysto-caval line). On the anterosuperior surface of the liver the bird passes piddling correct to the attachment of falciform ligament. The functional correct together with left lobes of the liver are of to a greater extent than or less equal inward size.

The liver is farther divided into segments. Each segment is supplied past times a principal branch hepatic artery together with portal vein together with the bile of these segments are collected past times a principal branch of hepatic duct. Each functional lobe of the liver consists of 4 segments. The segments I, II, III together with IV belong to the functional LEFT lobe together with segments V, VI, VII together with VIII to the functional RIGHT lobe.

The lobes tin last farther divided every bit right anterior (Segments V together with VIII) together with right posterior (Segments VI together with VII) sections/sectors inward the correct functional lobe together with left medial (Segment IV) together with left lateral (Segments II together with III) sections/sectors inward the left functional lobe. The hepatic veins prevarication inward liver parenchyma betwixt the sections.

Segment I corresponds to the gross anatomical caudate lobe together with segment IV to the quadrate lobe.

Peritoneal ligaments of the liver

Falciform ligament

Falciform ligament develops from ventral component of ventral mesogastrium. It attaches the liver to the anterior abdominal wall. It is a two-layered flexure of peritoneum that ascends from the belly clit to along the posterior surface of anterior abdominal wall. On reaching the superior surface of the liver, the ligament splits into correct together with left layers. The correct layer turns laterally together with forms the upper layer of the coronary ligament, (the extreme of which is called the right triangular ligament) whereas the left layer turns medially together with forms the anterior layer of left triangular ligament.

Falciform ligament has a sickle shaped costless margin that contains ligamentum teres hepatis or circular ligament of liver. Ligamentum teres represents the obliterated umbilical vein which extends from belly clit together with ascends upward inward costless margin of falciform ligament. On reaching the lower border of liver, ligamentum teres passes into the crack on the visceral (inferior) surface of the liver together with joins the left branch of the portal vein inward the porta hepatis.

Coronary Ligament

The coronary ligament is formed past times the reflection of the peritoneum from the diaphragm onto the posterior surfaces of the correct lobe of the liver. It consists of the upper/superior together with lower/inferior layers. Between the ii layers of this ligament bounded laterally past times groove for inferior venacava, at that topographic point is a large triangular expanse of liver devoid of peritoneal covering. This triangular expanse inward the liver is called the 'bare area' of the liver. This component of liver is attached to the diaphragm past times areolar tissue. The ii layers of coronary ligament reckon on the correct to cast the correct triangular ligament. The upper layer of the coronary ligament is reflected superiorly onto the inferior surface of the diaphragm together with inferiorly onto the correct together with superior surface of the liver. The lower layer of the coronary ligament reflects inferiorly over the correct suprarenal gland together with correct kidney, together with superiorly onto the inferior surface of the liver.

Triangular Ligaments

The left triangular ligament represents double layer of peritoneum which extends from diaphragm to a variable length over the superior border/surface of the left lobe of the liver. As already mentioned the anterior layer of the ligament is formed past times the left layer of falciform ligament whereas the posterior layer is continuous amongst the left layer of lesser omentum.

The right triangular ligament that forms the apex of the ‘bare area’ of liver is formed at the extreme of coronary ligament past times the spousal human relationship of its ii layers. It connects the correct surface of the liver to the diaphragm.

Lesser Omentum

The lesser omentum is too the peritoneal flexure that is attached on the margin of the porta hepatis together with the crack for the ligamentum venosum together with passes downward to the lesser curved shape of the tummy together with proximal component of duodenum. Thus lesser omentum has ii components- hepatogastric together with hepatoduodenal. The attachment to the liver is L-shaped. The vertical constituent follows the work of the crack for the Ligamentum venosum (Ligamentum venosum, the remains of ductus venosus, is attached to the left branch of the portal vein below together with the inferior venacava inward a higher identify together with runs inward the crack on the inferior surface of the liver.) The horizontal constituent attaches on the margin of porta hepatis. At its upper end, the superior or left layer of lesser omentum is continuous on the left amongst the posterior layer of the left triangular ligament, together with the inferior or correct layer is continuous on the correct amongst the coronary ligament every bit it encloses the inferior vena cava. At its lower end, it presents costless anterior margin where the ii layers diverge to enclose the portal vein, bile duct together with hepatic artery.

Neurovascular render of liver

The portal vein together with hepatic artery ascend inward the lesser omentum together with larn inward the liver at the porta hepatis, where each bifurcates into correct together with left branches. The hepatic bile duct together with lymphatic vessels larn out the liver at porta hepatis together with descend through the same omentum. The hepatic veins straight drain into the inferior vena cava after leaving the liver through it posterior surface.

Hepatic Artery:

It arises from the coeliac torso of abdominal aorta.

The artery may last subdivided into the mutual hepatic artery - from the coeliac torso to the beginning of the gastroduodenal artery - together with the hepatic artery 'proper' - from that quest to its bifurcation.

Course:

After its origin, it passes anteriorly together with laterally to the upper surface of showtime component of the duodenum. It together with thence moves frontwards beneath the peritoneal flooring (of epiploic foramen) together with reaches the costless border of the lesser omentum. It together with thence ascends inward the costless omental margin inward forepart of epiploic foramen. Here, the artery lies left to the mutual bile duct together with anterior to the portal vein. At the porta hepatis, it divides into correct together with left hepatic arteries.

Major Branches:

Right Gastric artery

Gastroduodenal artery

Cystic artery from correct hepatic artery

Veins

The liver has ii venous systems. The portal venous organization that conveys venous blood from the bulk of the alimentary canal together with its associated organs to the liver together with the hepatic venous organization that drains blood from the liver parenchyma into the inferior vena cava

Hepatic Veins

The hepatic veins choose blood from the liver to the inferior vena cava. The tributaries arise inside the parenchyma of the liver together with emerge from the posterior hepatic surface to opened upwards straight into the inferior vena cava inward its groove on the posterior hepatic surface.

Hepatic veins are arranged inward upper together with lower groups.

The veins inward upper grouping are unremarkably large together with commonly referred to every bit the right, middle together with left hepatic veins. The correct hepatic vein drains segments V, VI, VII together with VIII. The middle hepatic vein lies betwixt segments IV together with VIII together with drains both these segments together with segment V. The left hepatic vein drains segments II together with III amongst some drainage from segment IV.

The lower groups vary inward number together with extent of distribution. They drain segment I together with occasionally from segments VII together with VIII.

Lymphatic drainage

The lymphatic from the liver are arranged into ii sets:

Superficial lymphatics run inward subserous areolar tissue together with drain into:

Subdiaphragmatic lymph nodes (most of the posterior surface, surface of caudate lobe together with posterior component of inferior surface)
Hepatic lymph nodes (most of inferior surface, anterior together with most of the superior surface)
Coeliac lymph nodes (few lymphatics from correct surface)
Paracardiac lymph nodes ()few lymphatics from posterior surface of left lobe)

Deep lymphatics

Most of the liver parenchyma is drained past times deep lymphatic vessels introduce inside the centre of the liver. The lymph vessels partly accompany the hepatic veins together with drain into supra-diaphragmatic lymphnodes together with partly accompany portal vein draining into the hepatic lymph nodes.

Nerve supply

The liver parenchyma is supplied past times hepatic nerves, which arise from the hepatic plexus together with incorporate sympathetic together with parasympathetic (vagal) fibres. They larn inward the liver at the porta hepatis together with largely accompany the hepatic arteries together with bile ducts.

The capsule is supplied past times branches of the lower intercostal nerves, which too render the parietal peritoneum.

The hepatic plexus is the largest derivative of the coeliac plexus. It too receives branches from the anterior together with posterior vagus nerves. It accompanies the hepatic artery together with portal vein together with their branches into the liver, where its fibres run to a greater extent than or less the branches of the vessels. These branches render vasomotor fibres to the hepatic vessels together with biliary tree.

Branches to the gallbladder cast a frail cystic plexus. Multiple fine branches from the plexus render the mutual together with hepatic bile ducts directly. The vagal fibres are motor to the musculature of the gallbladder together with bile ducts together with inhibitory to the sphincter of the bile duct.

Ducts of liver

Bile ducts of the liver:

The bile ducts of the liver consist of correct together with left hepatic ducts, the mutual hepatic duct, the bile duct, the gall bladder together with the cystic duct.

The formation of intrahepatic bile duct is described inward the department structure of the liver. The Intrahepatic bile ducts at porta hepatis of the liver cast the correct together with left hepatic ducts. The correct hepatic duct drains the correct lobe of the liver whereas the left hepatic duct drains the left, caudate together with quadrate lobe of the liver.

Hepatic Duct

After the brusque course of pedagogy the correct together with left hepatic ducts unite to cast mutual hepatic duct which is virtually 1½ inches (4cm) long together with descends inside the costless margin of lesser omentum. It is joined on its correct side past times the cystic duct thereby forming the bile duct.

Bile duct

The bile duct or Common bile duct is virtually iii inches (8cm) long. In the showtime component of its course, it lies inward the correct costless margin of the lesser omentum whereas inward the minute component of its course, it lies behind the showtime component of the duodenum. Further inward the 3rd component of its course of pedagogy it lies inward a groove on the posterior surface of the caput of the pancreas. The bile duct ends past times piercing the wall of the minute component of the duodenum where it is unremarkably joined past times principal pancreatic duct together with together they opened upwards into the ampulla of Vater.

Gall Bladder

Location

It is a pear shaped sac lying on the inferior surface of the liver. It has a capacity of virtually 30-50 ml together with stores bile.

Presenting parts of gall bladder

Fundus, body together with neck

Fundus is rounded together with comes inward contact amongst the anterior abdominal wall at the degree of tip of the 9th costal cartilage.

The body lies inward contact amongst the liver surface together with is directed upward, backward together with to the left.

The neck becomes continuous amongst the cystic duct which turns into the lesser omentum to bring together the correct side of the mutual hepatic duct to cast the bile duct.

References
Gray's Anatomy
K. L. Moore's Clinically Oriented Anatomy
R. Snell's Clinical Anatomy