Liver and Biliary System Anatomy Notes
Liver Anatomy
Location and General Features
The liver is the largest gland in the body, weighing approximately 1.2 to 1.5 kg in adults.
Located primarily in the right hypochondrium, epigastrium, and left hypochondrium, it lies beneath the diaphragm.
Wedge-shaped with the base oriented to the right and the apex to the left, extending towards the left upper quadrant.
Anatomical Lobes and Ligaments
Anatomically divided into right and left lobes by three ligaments:
Falciform ligament: located on the anterior and superior surfaces; it attaches the liver to the anterior abdominal wall and contains the ligamentum teres.
Ligamentum venosum: located on the posterior surface, it is a remnant of the fetal ductus venosus.
Ligamentum teres: located on the inferior surface, it is the remnant of the fetal left umbilical vein.
Surface Anatomy
Upper border: A concavo-convex line following the contour of the diaphragm.
Right border: A curved line to the right, between:
The 7th rib in the right mid-axillary line.
1 cm below the costal margin in the right mid-axillary line.
Inferior border: Passes through several points:
1 cm below the costal margin in the right mid-axillary line.
The 9th costal cartilage in the right midclavicular line (Murphy’s point, indicating the surface anatomy of the fundus of the gall bladder).
The transpyloric plane in the midline (a hand breadth below the xiphisternal junction, or midway between the xiphisternal junction and umbilicus).
The tip of the left 8th costal cartilage.
The 5th intercostal space in the left midclavicular line.
Surfaces of the Liver
Anterior surface: Faces anteriorly and superiorly, related to the diaphragm and anterior abdominal wall.
Superior surface: Convex, fits under the diaphragm.
Right surface: Extends laterally, related to the ribs and diaphragm.
Posterior surface: Contains impressions for the esophagus, inferior vena cava, and vertebral column.
Inferior (visceral) surface: Contains the porta hepatis and is related to the stomach, duodenum, and gallbladder.
Relations of the Liver Surfaces
Superior Surface
Related to the costo-diaphragmatic recess of the pleura and separated from the lungs by the diaphragm.
Posterior Surface
Oesophageal groove: Impression for the esophagus.
Fissure for ligamentum venosum: A groove lodging the remnant of the ductus venosus.
Caudate lobe: Located on the posterior-superior surface, near the inferior vena cava.
Groove for inferior vena cava (IVC): A deep groove lodging the IVC.
Bare area proper: Area where the liver is in direct contact with the diaphragm, devoid of peritoneal covering.
Right triangular ligament: A peritoneal fold connecting the right lobe to the diaphragm.
Pons hepatis: A bridge of liver tissue.
Tuber omental: A projection near the lesser omentum.
NB: Lymph vessels from the bare area ascend through the vena caval opening of the diaphragm to end in the thoracic duct, crucial for lymphatic drainage.
Inferior Surface
Gastric impression: related to the fundus and body of the stomach.
Tuber omental: between the gastric area and the fissure for ligamentum venosum.
Fissure for ligamentum teres (round ligament of the liver): represents the obliterated left umbilical vein.
Quadrate lobe: related to the transverse colon, pyloroduodenal junction, and lesser omentum.
Gall bladder fossa: Depression lodging the gallbladder.
Relations of the inferior surface of the right lobe:
Gall bladder: Attached in the gall bladder fossa.
2nd part of the duodenum: Curving around the head of the pancreas.
Front of the right kidney: Separated by the peritoneum.
Right suprarenal gland: Superior to the kidney.
Right colic flexure: Inferior and lateral.
Porta hepatis (hilum): contains various structures entering and leaving the liver.
Ligaments as Remnants of Embryological Structures
Ligamentum venosum: obliterated fibrosed remnant of ductus venosus, conducting blood from the umbilical vein to the IVC in the fetus.
Ligamentum teres: obliterated fibrosed remnant of the left umbilical vein, carrying oxygenated blood from the placenta to the fetus.
Sub-phrenic Spaces
Potential spaces lying below the diaphragm in relation to the liver, falciform ligament, and abdominal wall, prone to abscess formation.
Classification:
Right anterior space: on the right side of the falciform ligament, between the right lobe of the liver and the diaphragm.
Left anterior space: on the left side of the falciform ligament, between the left lobe of the liver and the diaphragm, anterior abdominal wall, and antero-superior surface of the stomach.
Right posterior space (Morison's or hepatorenal pouch):
Anteriorly: inferior surface of the right lobe of the liver.
Posteriorly: anterior surface of the right kidney.
Superiorly: posterior layer of the coronary ligament.
Inferiorly: opens into the general peritoneal cavity.
Importance: it is the commonest site for subphrenic abscess because it is the most dependent area in the peritoneal cavity during lying down; significant for fluid accumulation in ascites.
Left posterior subphrenic space: the upper part of the lesser sac behind the caudate lobe of the liver.
Right extraperitoneal subphrenic space: between the liver and the diaphragm, between the upper and lower layers of the coronary ligament (bare area proper and diaphragm).
Left extraperitoneal subphrenic space: lies around the left suprarenal gland and the upper pole of the left kidney.
Factors Supporting the Liver
Hepatic veins connecting it with the IVC, ensuring direct drainage.
Intra-abdominal pressure and tone of the anterior abdominal wall, providing support from the front.
Peritoneal folds and ligaments attaching the liver to the diaphragm and the anterior abdominal wall, maintaining its position.
Fissures of the Liver
(A) Porta Hepatis (Hilum of Liver)
Definition: A transverse fissure between the posterior and inferior surfaces of the liver, serving as the entry and exit point for vessels and ducts.
Site: Lies between the quadrate lobe anteriorly and the caudate lobe and caudate process posteriorly.
Margins give attachment to the lesser omentum, connecting the liver to the stomach.
Contents (DAP):
Hepatic ducts (most anteriorly and near the right end of the hilum), draining bile from the liver.
Hepatic artery (in the middle and near the left end of the hilum), supplying oxygenated blood to the liver.
Portal vein (most posteriorly), carrying nutrient-rich blood from the gastrointestinal tract to the liver.
Hepatic nerve plexus (runs along the hepatic artery), providing autonomic innervation.
Lymph nodes, lymph vessels, and extraperitoneal fat, contributing to lymphatic drainage and support.
(B) Fissure for Ligamentum Teres
On the inferior surface, from the inferior border of the liver to the porta hepatis.
Lodges the ligamentum teres (obliterated left umbilical vein that connects the umbilicus with the left portal branch).
(C) Fissure for Ligamentum Venosum
On the posterior surface of the liver, from the porta hepatis to the superior surface of the liver.
Gives attachment to the lesser omentum and lodges the ligamentum venosum (obliterated ductus venosus that connects the left portal branch with the IVC in the fetus).
Blood Supply and Lymphatic Drainage
Blood supply:
Mainly the portal vein (70%), carrying deoxygenated, nutrient-rich blood from the gastrointestinal tract and spleen.
Hepatic artery (30%), supplying oxygenated blood from the aorta via the celiac trunk.
Inside the liver, blood from the portal vein and hepatic artery mixes in the sinusoids, allowing hepatocytes to process nutrients and toxins.
Blood is collected from each hepatic lobule in a central vein.
Central veins combine to form 2-3 hepatic veins, which join the inferior vena cava, draining deoxygenated blood from the liver.
Lymphatic drainage:
Lateral diaphragmatic lymph nodes: around the end of the inferior vena cava.
Paracardial lymph nodes: around the lower part of the oesophagus.
Hepatic lymph nodes: in the porta hepatis and free border of the lesser omentum.
Coeliac lymph nodes: around the coeliac trunk.
Lymphatic vessels:
Superficial lymph vessels run in the subserous areolar tissue.
Deep lymph vessels:
Ascending trunks accompany hepatic veins.
Descending trunks exit through the porta hepatis.
Bare Areas of the Liver
The liver is completely covered with peritoneum except for:
Bare area proper related to the diaphragm, on the posterior surface of the right lobe.
Groove for the inferior vena cava on the posterior surface.
Fossa for the gall bladder on the inferior surface.
Porta hepatis.
Fissure for the ligamentum venosum.
Fissure for the ligamentum teres.
Peritoneal Folds and Ligaments
I. Lesser Omentum (Gastro-hepatic ligament): between the stomach and the liver, containing the portal triad (hepatic artery, portal vein, and bile duct).
II. Falciform Ligament: Extends from the anterior abdominal wall and diaphragm to the superior and anterior surfaces of the liver.
Represents the anterior part of the ventral mesogastrium.
Formed of 2 layers (right and left).
Sickle-shaped.
Contents: ligamentum teres and para-umbilical veins.
III. Coronary Ligament: Extends from the back of the right lobe to the diaphragm behind the liver, defining the bare area.
IV. Right Triangular Ligament: Extends from the back of the right lobe of the liver, at the right end of the bare area, to the diaphragm.
V. Left Triangular Ligament: Extends from the upper surface of the left lobe of the liver to the under surface of the diaphragm.
Surgical and Physiological Divisions of the Liver
The liver is divided into 2 surgical lobes: true right and left lobes, by the interlobar fissure which extends from the gall bladder fossa to the inferior vena cava groove.
The true left lobe is further divided by the plane of the falciform and round ligament of the liver into:
Medial segment: subdivided transversely into superior and inferior segments.
Lateral segment: also subdivided transversely into superior and inferior segments.
The true right lobe is further divided by the coronary ligament into:
Anterior segment: subdivided into superior and inferior segments.
Posterior segment: subdivided into superior and inferior segments.
Therefore, there are 8 surgical segments, 4 in each lobe.
The plane of the middle hepatic vein corresponds to a plane running from the IVC to the gall bladder fossa, dividing the liver into functional right and left halves.
The liver is divided into 8 functionally independent segments (Couinaud's segments), each with its own vascular inflow, outflow, and biliary drainage, allowing for precise surgical resections.
NB: The right hepatic artery may arise from the superior mesenteric artery, while the left hepatic artery may arise from the left gastric artery, which is important to know during surgery.
Applied Anatomy
Liver hemorrhage can be controlled by the Pringle maneuver, clamping the hepatoduodenal ligament to interrupt blood flow through the hepatic artery and portal vein.
In adults, a normal liver is soft and cannot be felt below the costal margin unless there is a pathology, such as hepatomegaly.
Vascular segments are essential for partial hepatectomy and liver transplantation, enabling surgeons to remove or transplant specific liver segments without compromising the function of the remaining liver tissue.
Question 1
Case: A 40‐year‐old male trauma patient undergoes an emergency laparotomy. During surgery, the surgeon identifies a firm, fibrous cord running along the inferior border of the liver. This structure is used as an anatomical landmark and is known to be the remnant of the left umbilical vein. Which structure is it?
A. Falciform ligament B. Ligamentum venosum C. Ligamentum teres D. Coronary ligament E. Round ligament of the liver
Answer: C. Ligamentum teres
Explanation: The ligamentum teres (also called the round ligament of the liver) is the obliterated left umbilical vein and is seen as a fibrous cord along the inferior surface of the liver.
Question 2
Case: During preoperative planning for a liver resection, the surgeon reviews imaging and notes a deep, transverse fissure on the posterior surface of the liver that houses an obliterated fetal vessel (the ductus venosus). What is this fissure called?
A. Fissure for ligamentum teres B. Fissure for ligamentum venosum C. Porta hepatis D. Falciform fissure E. Hepatic sulcus
Answer: B. Fissure for ligamentum venosum
Explanation: The fissure for ligamentum venosum is located on the posterior surface of the liver and accommodates the ligamentum venosum, the fibrous remnant of the ductus venosus.
Question 3
Case: A 30‐year‐old woman presents with right upper quadrant pain and a positive Murphy’s sign, suggesting acute cholecystitis. On imaging, the gallbladder is visualized as protruding from the liver’s inferior surface. Which structure is found immediately posterior to the fundus of the gallbladder?
A. Transverse colon B. Duodenum C. Right kidney D. Hepatic flexure of the colon E. Pancreatic head
Answer: A. Transverse colon
Explanation: The gallbladder’s fundus typically protrudes below the liver’s inferior border and is in contact with the transverse colon posteriorly.
Question 4
Case: A 55‐year‐old man undergoing an endoscopic retrograde cholangiopancreatography (ERCP) is found to have a stone obstructing the junction where the cystic duct joins the hepatic duct. This junction results in the formation of which structure?
A. Common bile duct B. Porta hepatis C. Gallbladder neck D. Cystic duct E. Hepatic duct confluence
Answer: A. Common bile duct
Explanation: The union of the common hepatic duct (formed by the right and left hepatic ducts) with the cystic duct from the gallbladder forms the common bile duct.
Question 5
Case: During a liver anatomy demonstration, a professor points to a deep groove on the inferior surface of the liver that lodges a fibrous cord. This groove is directly associated with which structure?
A. Fissure for ligamentum venosum B. Fissure for ligamentum teres C. Porta hepatis D. Gallbladder fossa E. Transverse fissure
Answer: B. Fissure for ligamentum teres
Explanation: The fissure for ligamentum teres runs on the inferior aspect of the liver and contains the ligamentum teres (the remnant of the left umbilical vein).
Question 6
Case: A 60‐year‐old patient undergoing imaging for liver metastases has a CT scan showing a portion of the liver that is not covered by peritoneum and lies directly against the diaphragm. What is this area called?
A. Anterior surface adjacent to the falciform ligament B. Bare area of the liver C. Gallbladder fossa D. Lateral segment under the coronary ligament E. Superior surface beneath the diaphragm
Answer: B. Bare area of the liver
Explanation: The bare area of the liver is a portion on the posterior surface (especially near the inferior vena cava) that is not covered by peritoneum, allowing direct contact with the diaphragm.
Question 7
Case: During a liver transplant, the surgeon dissects a peritoneal fold that extends from the anterior abdominal wall and diaphragm to the liver’s superior and anterior surfaces. Which structure is being mobilized?
A. Coronary ligament B. Falciform ligament C. Triangular ligament D. Ligamentum venosum E. Ligamentum teres
Answer: B. Falciform ligament
Explanation: The falciform ligament connects the anterior surface of the liver to the anterior abdominal wall and diaphragm and is a key landmark in liver surgery.
Question 8
Case: A patient with hepatocellular carcinoma requires a segmental liver resection. The liver is known to be divided into several functionally independent segments. How many such segments are there?
A. 2 segments B. 4 segments C. 6 segments D. 8 segments E. 10 segments
Answer: D. 8 segments
Explanation: The liver is divided into 8 surgical segments, each being functionally independent with its own vascular inflow, outflow, and biliary drainage.
Question 9
Case: In a patient undergoing evaluation for cholangiocarcinoma, an ultrasound shows the porta hepatis. Which of the following is NOT typically a structure found within the porta hepatis?
A. Hepatic ducts B. Hepatic artery C. Portal vein D. Hepatic veins E. Lymphatic vessels
Answer: D. Hepatic veins
Explanation: At the porta hepatis, you typically find the hepatic ducts, hepatic artery, portal vein, and lymphatic channels. The hepatic veins, however, drain the liver into the inferior vena cava and do not pass through the porta hepatis.
Question 10
Case: An oncology patient with liver metastases is evaluated for lymphatic spread. Deep lymphatic vessels from the liver exit through the porta hepatis. Into which group of lymph nodes do these vessels predominantly drain?
A. Lateral diaphragmatic lymph nodes B. Paracardial lymph nodes C. Hepatic lymph nodes D. Celiac lymph nodes E. Inguinal lymph nodes
Answer: C. Hepatic lymph nodes
Explanation: Deep lymphatics from the liver, exiting via the porta hepatis, primarily drain into the hepatic lymph nodes, which then connect with other regional nodes.
Question 11
Case: A 32‐year‐old female with suspected acute cholecystitis is taken for laparoscopic cholecystectomy. For hemostasis during the procedure, the surgeon must control the arterial supply to the gallbladder. Which artery is primarily responsible?
A. Hepatic artery proper B. Cystic artery C. Right gastric artery D. Gastroduodenal artery E. Superior mesenteric artery
Answer: B. Cystic artery
Explanation: The gallbladder is primarily supplied by the cystic artery, often a branch of the right hepatic artery. Identification and ligation of the cystic artery are key steps during cholecystectomy.
Question 12
Case: A patient sustains blunt abdominal trauma. In the course of the surgical exploration, the surgeon notes a peritoneal reflection that attaches the liver’s right lobe to the diaphragm over the bare area. What is the name of this ligament?
A. Falciform ligament B. Coronary ligament C. Triangular ligament D. Round ligament E. Hepatoduodenal ligament
Answer: B. Coronary ligament
Explanation: The coronary ligament is a reflection of peritoneum that attaches the superior (bare) surface of the liver to the diaphragm, playing an important role in liver stabilization.
Question 13
Case: A 50‐year‐old man presents with right upper quadrant pain that radiates to the right shoulder. This referred pain is due to diaphragmatic irritation. Which nerve is most commonly responsible for this referred pain?
A. Vagus nerve B. Greater splanchnic nerve C. Phrenic nerve D. Intercostal nerve E. Femoral nerve
Answer: C. Phrenic nerve
Explanation: The phrenic nerve (C3–C5) supplies the diaphragm and can refer pain to the shoulder region; it is often implicated in cases of cholecystitis or subdiaphragmatic irritation.
Question 14
Case: During a cholecystectomy, the surgeon notes that the gallbladder is closely apposed to the liver. Its attachment is via a layer that includes the visceral peritoneum covering the liver’s inferior surface along with loose connective tissue. Which of the following best describes this attachment?
A. Visceral peritoneum B. Parietal peritoneum C. Lesser omentum D. Greater omentum E. Hepatic capsule
Answer: A. Visceral peritoneum
Explanation: The gallbladder is attached to the liver through its visceral peritoneum and the underlying loose connective tissue, which also contains small vascular structures.
Question 15
Case: A medical student reviewing embryology notes learns that the liver bud arises from an endodermal outgrowth of the foregut. Which portion of the liver bud is responsible for forming the gallbladder and the cystic duct?
A. Pars hepatica B. Pars cystica C. Ductus venosus D. Septum transversum E. Hepatic cord
Answer: B. Pars cystica
Explanation: The liver bud divides into the pars hepatica and pars cystica. The pars cystica gives rise to the gallbladder and the cystic duct, whereas the pars hepatica forms the liver proper.