Large Intestine Anatomy

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Questions and Answers

What is the clinical significance of vascular segments in the spleen regarding surgical procedures?

  • They dictate the spleen's role in hematopoiesis after birth.
  • They define areas of immune surveillance within the spleen.
  • They determine the extent of splenic mobility during palpation.
  • They enable subtotal splenectomy due to relatively avascular planes. (correct)

What embryological characteristic explains the spleen's function in the body?

  • Its development from the mesoderm of the dorsal mesentery.
  • Its separation from the kidneys by a weak fascial septum.
  • Its hematopoietic function prenatally transitioning to immune functions postnatally. (correct)
  • Its close association with the pancreas and the tail of the pancreas.

Which structural feature of the spleen contributes to its ability to expel blood into circulation?

  • The thin fibrous capsule covered by visceral peritoneum.
  • The gastrosplenic ligament connecting it to the stomach.
  • The diaphragmatic surface fitting the adjacent ribs.
  • The smooth muscle in its capsule and trabeculae. (correct)

How does the thin fibrous capsule of the spleen contribute to its clinical vulnerability?

<p>It allows for marked expansion and contraction of the spleen. (A)</p> Signup and view all the answers

In the context of rib fractures, why is the spleen's proximity to the ribs potentially detrimental, despite the protective function?

<p>Sharp bone fragments may lacerate the spleen. (A)</p> Signup and view all the answers

Which anatomical relationship explains why palpating the notched border of the spleen can be diagnostically useful?

<p>The notched border lies inferomedially when the spleen is enlarged. (D)</p> Signup and view all the answers

A surgeon is planning a splenectomy. Understanding the splenic blood supply, what should the surgeon know about the arterial supply to the spleen before the procedure?

<p>The lack of anastomosis of arterial vessels results in the formation of vascular segments in the spleen. (D)</p> Signup and view all the answers

Which of the following describes the venous drainage of the spleen and its significance?

<p>The splenic vein unites with the superior mesenteric vein to form the hepatic portal vein, carrying blood to the liver. (D)</p> Signup and view all the answers

Which anatomical structure directly relates to the posterior surface and superior border of the pancreas?

<p>The pancreaticosplenic nodes. (B)</p> Signup and view all the answers

Given its lymphatic drainage pathways, where would a clinician expect to find metastases from a splenic tumor?

<p>Celiac and pancreaticosplenic lymph nodes. (A)</p> Signup and view all the answers

Considering the autonomic innervation of the spleen, what physiological effect do the post synaptic sympathetic fibers have on its function?

<p>They innervate smooth muscle in the splenic capsule, trabeculae, and intrasplenic vessel causing vasoconstriction. (D)</p> Signup and view all the answers

A patient presents with referred pain due to gallbladder inflammation. Which nerve, if irritated, could be responsible for this pain referral?

<p>The right phrenic nerve due to somatic afferent fibers. (D)</p> Signup and view all the answers

During a cholecystectomy, a surgeon identifies Calot's triangle. What anatomical structures define the boundaries of this triangle?

<p>Cystic duct, common hepatic duct, and visceral surface of the liver. (B)</p> Signup and view all the answers

After a cholecystectomy, a patient develops bile leakage. Which anatomical variation might explain this complication?

<p>The presence of an accessory hepatic duct joining the biliary system outside the liver. (A)</p> Signup and view all the answers

How does the structure of the cystic duct contribute to the regulation of bile flow?

<p>It has a spiral fold that offers resistance to sudden dumping and keeps the duct open. (D)</p> Signup and view all the answers

A patient is diagnosed with cholecystitis due to a gallstone blocking the cystic duct. What is the most likely physiological consequence of this blockage?

<p>Backflow obstruction results in the enlargement and inflammation of the gallbladder. (D)</p> Signup and view all the answers

A patient undergoes a liver biopsy. Knowing the organ's anatomy, through which intercostal space and line is the needle typically inserted, and why is this location preferred?

<p>The 10th intercostal space in the midaxillary line to reduce the risk of damaging the lung. (A)</p> Signup and view all the answers

A surgeon is planning a hepatic lobectomy. What underlying anatomical principle allows for the surgical resection of liver segments?

<p>The independent blood supply and biliary drainage of each hepatic segment. (C)</p> Signup and view all the answers

What explains why the liver is a common site for metastatic carcinoma?

<p>The hepatic portal vein drains the gastrointestinal tract, thus secondarily spreading tumors drained by the portal system of veins. (C)</p> Signup and view all the answers

How do the anterior and posterior surfaces of the liver differ in terms of peritoneal covering, and what is the clinical significance of this difference?

<p>The posterior surface lacks peritoneal covering (bare area), potentially allowing direct spread of infection. (B)</p> Signup and view all the answers

What is the clinical consequence of portal hypertension, and what anatomical feature contributes to its development?

<p>Esophageal varices due to diminished circulation through venous structures; absence of valves in hepatic portal vein. (C)</p> Signup and view all the answers

Why is the hepatic portal system clinically significant?

<p>It carries nutrient-rich blood from the digestive system directly to the liver for processing. (A)</p> Signup and view all the answers

A patient presents with jaundice and abdominal pain. An obstruction of the hepatopancreatic ampulla is suspected. Which anatomical structure is directly affected by this condition?

<p>The flow of bile and pancreatic secretions into the duodenum. (A)</p> Signup and view all the answers

A patient is suspected of having a blockage in either their bile duct or pancreatic duct. Which procedure would be most useful in determining the location of the blockage?

<p>Cholangiopancreatography. (A)</p> Signup and view all the answers

Select the statement that is most accurate regarding the spleen anatomy and function:

<p>The sympathetic fibers are conveyed to the large intestine via abdominopelvic splanchnic nerves via the prevertebral ganglia and periarterial plexuses. (A)</p> Signup and view all the answers

What is the significance of the ligamentum teres hepatis?

<p>It is the inferior border of the falciform ligament. (A)</p> Signup and view all the answers

What is NOT a surface that forms the visceral surface of the liver?

<p>Bile Duct. (D)</p> Signup and view all the answers

In the context of liver anatomy, what is unique about the Quadrate and Caudate lobes?

<p>They are accessory lobes, and separated from the interior by the porta hepatis. (A)</p> Signup and view all the answers

What is the significance of the porta hepatis?

<p>It is a transverse fissure where vessels, nerves and hepatic ducts enter and leave. (B)</p> Signup and view all the answers

Choose the statement that best describes the relationship between the Inferior Vena Cava (IVC) to Hepatic Veins and Liver:

<p>Hepatic veins open directly into the IVC where it is just inferior to the diaphragm. (D)</p> Signup and view all the answers

What is cholecystokinin (CCK) and what role does it serve in the body?

<p>It is a hormone produced by the duodenal walls that stimulate gallbladder contractions. (B)</p> Signup and view all the answers

What is the key lymphatic vessel for the cystic duct and liver?

<p>Celiac Lymph Nodes. (A)</p> Signup and view all the answers

Which arteries supply the bile duct?

<p>Cystic, Right Hepatic and a portion of the Pancreaticoduodenal Arteries. (A)</p> Signup and view all the answers

Which statement best describes a gallstone?

<p>It is a concretion in the gallbladder, cystic duct of bile duct composed chiefly of cholesterol crystals. (A)</p> Signup and view all the answers

If a gallstone blocks the cystic duct causing inflammation in the gallbladder causing it to enlarge, can this lead to:

<p>A breakdown in the wall between the gall bladder and duodenum. (B)</p> Signup and view all the answers

During a cholecystectomy, which key liver anatomical location is most crucial to identify arteries and hepatic:

<p>Cystohepatic triangle. (B)</p> Signup and view all the answers

During the surgical exploration of the spleen, a surgeon encounters significant bleeding originating from a deep laceration. Assuming standard splenic arterial segmentation, which of the locations would least likely offer an avascular plane for clamping to control hemorrhage?

<p>The splenic hilum where main arterial branches enter. (D)</p> Signup and view all the answers

Considering the spleen's location in the left upper quadrant and its relationship to the adjacent ribs, what is the most likely consequence of a severe, penetrating trauma to the lower thoracic region?

<p>Rupture of spleen. (B)</p> Signup and view all the answers

How would significant enlargement of the spleen (splenomegaly) alter the anatomical relationship between the spleen and the left kidney?

<p>The left kidney is displaced inferiorly and medially. (D)</p> Signup and view all the answers

Following a traumatic injury, a patient exhibits signs of splenic rupture. Given the spleen's structure, where would intraperitoneal hemorrhage most likely accumulate first when the patient is in a supine position?

<p>The left subphrenic space. (B)</p> Signup and view all the answers

During a splenectomy, the surgeon must carefully identify the ligaments connected to the spleen to avoid injury to adjacent structures. Which ligament directly connects the spleen to the greater curvature of the stomach?

<p>Gastrosplenic ligament. (C)</p> Signup and view all the answers

A clinician suspects a splenic infarction due to the splenic artery's unique branching. Which statement best describes the pattern that contributes to increased vulnerability to infarction?

<p>The splenic artery divides into multiple branches with minimal anastomosis. (B)</p> Signup and view all the answers

A patient presents with pancreatitis. Considering the anatomical relationship between the pancreas and spleen, which complication is most likely to occur due to inflammation-induced compression?

<p>Splenic vein thrombosis. (C)</p> Signup and view all the answers

Following a motor vehicle accident, imaging reveals damage to the tail of the pancreas where it comes into close proximity with the splenic hilum. Which vascular structure is most at risk?

<p>Splenic artery. (D)</p> Signup and view all the answers

A patient undergoing evaluation for pancreatic cancer is found to have a tumor in the neck of the pancreas. Considering the anatomical relationships, which vascular structure is most immediately at risk?

<p>Splenic vein. (B)</p> Signup and view all the answers

During a surgical procedure involving the pancreas, a surgeon must consider the arrangement of the pancreatic ducts. In a scenario where the main pancreatic duct is obstructed, what compensatory mechanism might maintain exocrine function?

<p>Draining through the accessory pancreatic duct. (A)</p> Signup and view all the answers

A surgeon is planning a Whipple procedure (pancreaticoduodenectomy). Which anatomical relationship requires careful attention to prevent complications related to vascular supply?

<p>The relationship of the superior mesenteric vessels to the uncinate process. (A)</p> Signup and view all the answers

A patient undergoes a liver biopsy. Post-procedure, the patient develops significant hemoperitoneum. Which anatomical characteristic of the liver contributes most significantly to this complication?

<p>The dual blood supply via the hepatic artery and portal vein. (A)</p> Signup and view all the answers

A patient diagnosed with liver cirrhosis develops ascites. What is the underlying anatomical basis for this condition?

<p>Scarring of the liver reduces blood flow through the organ increasing hydrostatic pressure in the hepatic portal vein. (B)</p> Signup and view all the answers

A surgeon performing a cholecystectomy identifies Calot's triangle. What complication is most likely if the surgeon fails to appreciate variations within this anatomical space?

<p>Ligation of the common bile duct. (D)</p> Signup and view all the answers

During an ERCP (endoscopic retrograde cholangiopancreatography) procedure, the endoscope is advanced through the duodenum to visualize the biliary and pancreatic ducts. What anatomical landmark signals the location of the hepatopancreatic ampulla where cannulation is required?

<p>The major duodenal papilla. (D)</p> Signup and view all the answers

Flashcards

Large Intestine (Orad)

Large intestine part proximal to the left colic flexure.

Sympathetic Fibers

Fibers that are conveyed to the large intestine.

Spleen Location

Organ located in the left upper quadrant (LUQ).

Function of Spleen

Blood-forming organ prenatally; removes old RBCs postnatally.

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Fibroelastic Capsule

Capsule covering the spleen

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Splenic Hilum

The area where vessels enter and leave the spleen

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Diaphragmatic Surface

Surface that is convexly curved to fit against the diaphragm.

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Gastrosplenic Ligament

Ligament that connects the spleen to the stomach.

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Splenic Artery

Largest branch of the celiac trunk supplying spleen.

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Splenic Vein

Vein formed by tributaries from the splenic hilum.

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Pancreaticosplenic Nodes

Lymph nodes that drain lymph from the splenic vessels.

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Nerves of the Spleen

Nerves mainly along splenic artery branches, vasomotor function.

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Pancreatic Juice

Secretion produced by the pancreas.

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Endocrine Secretions

Hormones produced by the pancreas.

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Head of Pancreas

Expanded part of the gland embraced by the duodenum.

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Uncinate Process

Projection from inferior part of pancreatic head, posterior to SMA.

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Neck of Pancreas

The pancreatic part that has a short length and which overlies mesenteric vessels.

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Sphincter of Bile Duct

Sphincter that plays a role in controlling digestive secretion flow.

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Pancreatic Arteries

Form several arcades with branches of gastroduodenal arteries.

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Liver

The largest gland in the body that stores glycogen

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Bile

Fluid secreted by the liver, aiding in fat emulsification.

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Diaphragmatic Surface

Surface that is smooth and dome shaped.

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Hepatorenal Recess

It's a posterosuperior extension of the subhepatic space.

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Peritoneal Reflections

The attachments are cut and placed on the specimen's right.

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Bare Area of Liver

Area without peritoneal covering on the diaphragmatic surface.

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Falciform Ligament

The anterior layer is continuous, and the posterior layer is continuous with right layer of lesser omentum.

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Porta Hepatis

Transverse fissure where vessels, nerves, and ducts enter/leave.

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The Umbilical Fissure

This fissure is formed anteriorly and posteriorly.

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Lesser Omentum

Encloses the portal triad, passes to stomach's lesser curvature.

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Visceral Surface

Relationship of liver to stomach, duodenum, omentum, gallbladder.

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Hepatic Plexus

The two branches passes between the layers

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Biliary Ducts

What conveys bile to the duodenum.

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Liver Lobules

What normal hepatic tissue demonstrates when sectioned.

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Bile Canaliculi

Where the hepatocytes secrete bile.

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Hepatic Ducts

The right and left liver are drained by these

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Bile Duct

What forms in the free edge of the lesser omentum.

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Common hepatic duct

Forms the free edge of the lesser omentum.

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Cystic Artery

Arterial supply to the proximal part of the duct.

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Cystic veins

Where the veins usually enter

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Gallbladder

Lies in the fossa for the gallbladder

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Fundus

Wide, blunt end of the gallbladder.

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Cystic Duct

Connects the neck of the gallbladder.

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Cystic Artery

Origin and the course varies

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Hepatic Portal Vein (HPV)

Main channel of the portal venous system.

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Portal-Systemic Anastomoses

Communications between portal & systemic venous systems.

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Caput Medusae

Distended cutaneous veins radiating from the umbilicus

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Portosystemic Shunts

Procedure to divert blood from portal to systemic system.

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Study Notes

  • The large intestine, suspended by the sigmoid mesocolon, shows significant variability in length and disposition and concludes at the rectosigmoid junction, where the teniae, haustra, and omental appendices end anterior to the third sacral segment.
  • The superior mesenteric vessels supply the large intestine proximal to the left colic flexure, while the inferior mesenteric vessels supply most of the large intestine distal to the flexure.
  • Cranial and sacral parasympathetic innervation of the alimentary tract divides at the left colic flexure.
  • Sympathetic fibers reach the large intestine through abdominopelvic splanchnic nerves and prevertebral ganglia, while the middle of the sigmoid colon marks a sensory innervation divide.
  • The spleen is an ovoid, purplish mass, about the size and shape of a fist, located in the left upper quadrant (LUQ) or hypochondrium of the abdomen, it is considered the most vulnerable abdominal organ.
  • The spleen is the largest lymphatic organ, functioning in lymphocyte proliferation, immune surveillance, and response as part of the body's defense system.
  • Prenatally, the spleen is hematopoietic, but after birth, it identifies, removes, and destroys expended red blood cells and platelets, recycling iron and globin.
  • The spleen acts as a blood reservoir, storing RBCs and platelets and aids "self-transfusion" during hemorrhage, but despite its size and functions, it is a non-vital organ.
  • The spleen's structure includes a soft, vascular mass with a delicate fibroelastic capsule, covered by visceral peritoneum except at the splenic hilum, along with splenic artery and vein entry/exit points, facilitating expansion and contraction.
  • The spleen is mobile and typically rests on the left colic flexure, associated posteriorly with the left 9th–11th ribs, separated by the diaphragm and costodiaphragmatic recess.
  • The spleen’s relations include the stomach anteriorly, the diaphragm posteriorly, the left colic flexure inferiorly, and the left kidney medially.
  • Spleen size varies, but it averages approximately 12 cm long and 7 cm wide and 1 inch thick, 3 inches wide, and 5 inches long and weighs 7 ounces.
  • The diaphragmatic surface is convexly curved, fitting the diaphragm and adjacent ribs; anterior and superior borders are sharp and often notched.
  • The posterior end and inferior border are rounded; the spleen typically doesn't extend below the left costal margin unless enlarged or hardened.
  • The spleen has a thin fibrous capsule and trabeculae carrying blood vessels, containing a large blood quantity expelled into circulation via smooth muscle action.
  • The splenic artery supplies blood, dividing into five or more branches at the hilum, forming vascular segments due to limited anastomosis, aiding subtotal splenectomy.
  • The splenic vein drains blood, formed by tributaries from the hilum, joining the IMV and running behind the pancreas, uniting with the SMV to form the hepatic portal vein.
  • Splenic lymphatic vessels extend to the pancreaticosplenic lymph nodes and then to the celiac nodes.
  • Nerves from the celiac plexus distribute along splenic artery branches, regulating function as vasomotor nerves.
  • The pancreas is an elongated accessory digestive gland that produces exocrine (pancreatic juice) and endocrine (glucagon and insulin) secretions.
  • It sits retroperitoneally, transversely crossing the L1 and L2 vertebrae, posterior to the stomach and between the duodenum and spleen.
  • The pancreas is divided into four parts: head, neck, body, and tail; main and accessory pancreatic ducts enter the duodenum.
  • The head of the pancreas is embraced by the duodenum, with the uncinate process extending posteriorly to the SMA.
  • The pancreatic head rests posteriorly on the IVC, renal artery/vein; the bile duct is embedded in its surface.
  • The neck of the pancreas, short and overlying the mesenteric vessels, has an anterior surface adjacent to the pylorus and the SMV joining the splenic vein posteriorly to form the hepatic portal vein.
  • The body of the pancreas stretches from the neck over the aorta/L2 vertebra, covered with peritoneum, and contacts the aorta, SMA, left suprarenal gland, kidney, and renal vessels posteriorly.
  • The tail of the pancreas lies anterior to the left kidney close to the hilum and is mobile, running through the splenorenal ligament with splenic vessels.
  • The main pancreatic duct runs the length of the gland and links to the bile duct to create the hepatopancreatic ampulla, which opens into the duodenum.
  • Sphincters control digestive secretions and duodenal content, but only the bile duct sphincter significantly regulates bile flow into the duodenum.
  • The accessory pancreatic duct opens into the duodenum, usually communicating with the main duct or solely carrying pancreatic juice.
  • The pancreas' arterial supply includes multiple pancreatic arteries from the splenic, gastroduodenal, and superior mesenteric arteries, while venous drainage flows via pancreatic veins to parts of the splenic and superior mesenteric vein.
  • Lymphatic vessels follow blood vessels to pancreaticosplenic lymph nodes, draining to superior mesenteric or celiac nodes.
  • The nerves of the pancreas are vagus and abdominopelvic splanchnic nerves from the celiac and superior mesenteric plexuses, some fibers control pancreatic secretions.
  • The liver is the body's largest gland, weighing 1,500 g, composing 2.5% of adult body weight (5% in mature fetus), conveying nutrients via the portal venous system, storing glycogen, and secreting bile for fat emulsification.
  • Bile follows the hepatic ducts to the common hepatic duct, uniting with the cystic duct, bile production is continuous, with accumulation and storage in the gallbladder.
  • The liver resides mainly in the right upper abdomen, shielded by the thoracic cage/diaphragm, its surface projection extends deep to ribs 7–11.
  • The liver comprises of convex diaphragmatic surface (anterior, superior, and some posterior) and a relatively flat or even concave visceral surface which are separated anteriorly by its sharp inferior border, following the right costal margin inferior to the diaphragm.
  • The diaphragmatic surface is positioned near the concavity of the diaphragmatic inferior surface to separate it from the pleurae, lungs, peritoneum, and heart.
  • Subphrenic recesses occur between the diaphragm and anterior/superior liver aspects; hepatorenal recess (Morison pouch) is a posterosuperior space extension, draining fluid from the omental bursa and connecting to the subphrenic recess.
  • Recesses are potential spaces containing enough fluid to lubricate the peritoneal membranes, which divides into right and left recesses by the falciform ligament.
  • The visceral surface is covered with visceral peritoneum, with the exclusion of the fossa for the gallbladder and the porta hepatis, it is connected to the stomach by the gastrosplenic ligament and lesser omentum, and to the left kidney by the splenorenal ligament.
  • The hilum constitutes the left boundary of the omental bursa and is often in contact with the pancreas tail.
  • Right colix flexure and right transverse colon lie along its right side.
  • Inferior vena cava, ligamentum venosum, gastric and pyloric areas are marked by fissures.
  • Umbilical fissure is split into fissure for the round ligament and fissure for the ligamentum venosum.
  • The lesser omentum (hepatogastric ligament) connects the liver to the stomach, while the hepatoduodenal ligament connects the liver to the porta hepatis.
  • Externally, it is divided into two anatomical lobes and two accessory lobes marked by peritoneum reflections.
  • The midline is defined by the falciform ligament attachment separating the right lobe from the left.
  • On the visceral surface the right and left fissures separate the quadrate lobe anteriorly and the caudate lobe posteriorly.
  • The liver is functionally divided into the right and left livers which receive its own primary branch with hepatic artery and portal vein and is drained by the hepatic duct.
  • For each 8, the caudate lobe's vascularization is independent that is drained by hepatic veins.
  • Hepatic Veins (right, intermediate, left) are intersegmental in distribution and function.

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