Articles

Articles are a collaborative effort to provide a single canonical page on all topics relevant to the practice of radiology. As such, articles are written and edited by countless contributing members over a period of time. A global group of dedicated editors oversee accuracy, consulting with expert advisers, and constantly reviewing additions.

53 results found
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Abdominal surface anatomy

The abdomen, when looking from in front, is divided into nine regions by imaginary planes (two vertical and two horizontal) forming abdominal surface anatomy. The nine regions are of clinical importance when examining and describing pathologies related to the abdomen. The horizontal planes are o...
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Accessory gallbladder

Accessory gallbladders are a rare anatomical variant occurring in 0.03% of cases (approximately 1 in 3000 people). They can arise from either the left or right hepatic ducts or both. Accessory gallbladders arise from a bifid diverticulum of the hepatic duct in the 5th or 6th week of development ...
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Accessory right inferior hepatic vein

An accessory right inferior hepatic vein is the most common variation of the hepatic veins.  It is present in up to 48% of the population and drains the posterior part of the right lobe (mainly segments 6 and 7) directly into the inferior vena cava. Variations in hepatic vascular anatomy are pa...
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Agenesis of the left hepatic lobe

Agenesis of the left hepatic lobe is a rare variation in liver anatomy. It is clinically asymptomatic and discovered during imaging or surgery. Radiographic features absence of the left hepatic lobe (left of the falciform ligament, Couinaud segments II and III) absence of left hepatic artery,...
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Agenesis of the right hepatic lobe

Agenesis of the right hepatic lobe is a rare variation in liver anatomy. Radiographic features absence of the right hepatic lobe absence of right hepatic artery, right portal vein, and right hepatic biliary system compensatory hypertrophy of the left hepatic lobe and caudate lobe possible r...
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Ampulla of Vater

The ampulla of Vater is a conical structure at the confluence of the common bile duct (CBD) and the main pancreatic duct that protrudes at the major duodenal papilla into the medial aspect of the descending duodenum. The entire structure is encased by smooth muscle fibers that compose the sphinc...
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Anatomy curriculum

The anatomy curriculum is one of our curriculum articles and aims to be a collection of articles that represent the core anatomy knowledge for radiologists and imaging specialists. General anatomy Neuroanatomy Head and neck anatomy Thoracic anatomy Abdominal and pelvic anatomy Spinal anat...
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Ansa pancreatica

The ansa pancreatica is a rare type of anatomical variation of the pancreatic duct. It is a communication between the main pancreatic duct (of Wirsung) and the accessory pancreatic duct (of Santorini). Recently, the ansa pancreatica has been considered as a predisposing factor in patients with i...
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Beaver tail liver

Beaver tail liver, also known as a sliver of liver, is a variant of hepatic morphology where an elongated left liver lobe extends laterally to contact and often surround the spleen. It is more common in females. The parenchyma is normal and thereby has the same risks of hepatic pathology as the ...
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Biliary tree anatomy

Various channels that collect bile from the hepatic parenchyma and transport it to the duodenum constitute the biliary tree. Gross anatomy By convention the biliary tree is divided into intra- and extra-hepatic bile ducts 1. There is significant variation in the biliary tree with the classical...
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Calot triangle

Calot triangle is a small (potential) triangular space at the porta hepatis of surgical importance as it is dissected during cholecystectomy. Its contents, the cystic artery and cystic duct must be identified before ligation and division to avoid damaging them during the operation. Gross anatom...
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Coeliac artery

Coeliac artery (also known as the coeliac axis or trunk) is a major visceral artery in the abdominal cavity.  Gross anatomy Origin Arises anteriorly from abdominal aorta at the T12 level, behind the median arcuate ligament, just as the aorta enters the abdomen.  Course It is typically a sho...
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Common bile duct

The common bile duct (CBD), which is sometimes simply known as the bile duct, is formed by the union of the cystic duct and common hepatic duct.  Gross anatomy The CBD is approximately 8 cm long and usually <6 mm wide in diameter but this can be dependent on a number of factors including age a...
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Common hepatic artery

The common hepatic artery (CHA) is a terminal branch of the coeliac artery. Gross anatomy Origin and course The CHA is a terminal branch of the coeliac artery, it passes to the right in the lesser sac, and enters the lesser omentum to pass slightly upwards towards the porta hepatis. It gives ...
Article

Couinaud classification of hepatic segments

The Couinaud classification (pronounced kwee-NO) is currently the most widely used system to describe functional liver anatomy. It is the preferred anatomy classification system as it divides the liver into eight independent functional units (termed segments) rather than relying on the tradition...
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Couinaud classification of hepatic segments (mnemonic)

Pauli et al published a "handy" way to remember the Couinaud classification of hepatic segments 1. Make a fist with your right hand. The fingers should be wrapped around the flexed thumb and the fist should face you. The segments are represented by the following: segment I (caudate): the thumb...
Article

Cystic artery

The cystic artery represents the main blood supply to the gallbladder. It most commonly arises from the right hepatic artery within Calots triangle 1. Gross anatomy The cystic artery passes posterior to the cystic duct to reach the neck of the gallbladder. At this point, it gives off two-to-fo...
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Ectopic intracaval liver

Ectopic intracaval liver is a rare congenital abnormality of the liver in which a part of the liver invaginates the inferior vena cava (IVC). Lobar or segmental agenesis, Riedel lobe, and ectopic hepatic lobes have been described as congenital abnormalities 1. The term ectopic intracaval may be ...
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Ectopic pancreatic tissue

Ectopic pancreatic tissue (or heterotopic pancreatic tissue) refers to the situation where rests of pancreatic tissue lie outside and separate to the pancreatic gland. Most patients are completely asymptomatic. Epidemiology It is reportedly relatively common, affecting ~5% (range 1-10%) 1 of p...
Article

Falciform ligament

The falciform ligament is a broad and thin peritoneal ligament. It is sickle-shaped (Latin: "falciform") and a remnant of the ventral mesentery of the fetus. It is situated in an anteroposterior plane but lies obliquely so that one surface faces forward and is in contact with the peritoneum beh...
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Gallbladder

The gallbladder is a pear-shaped musculomembranous sac, lodged in a fossa on the undersurface of the right lobe of the liver, and extending from near the right extremity of the porta hepatis to the anterior border of the liver.  Gross anatomy It typically measures from 7 to 10 cm in length and...
Article

Gallbladder agenesis

Agenesis of the gallbladder is a rare congenital anomaly. Epidemiology The incidence is <0.1% (range 0.04-0.1%). There is strong female predominance present among the symptomatic cases. Clinical presentation Most patients with agenesis of the gallbladder are asymptomatic. Although some patie...
Article

Gallbladder duplication

Gallbladder duplication is a rare anatomic anomaly characterised by the presence of an accessory gallbladder. There is no increased risk for malignancy or calculi compared to a single gallbladder. Epidemiology Prevalence is estimated at 1 in 3000.  Classification Boyden's classification divi...
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Gallbladder triplication

Gallbladder triplication is an extremely rare anomaly. There are three types of gallbladder triplication are described according to the number of cystic duct and their insertion: Three gallbladders and three cystic ducts which unite to form a common cystic duct before joining the common bile du...
Article

Hepatic artery proper

The hepatic artery proper or the proper hepatic artery arises from the common hepatic artery as it divides into its two terminal branches, the hepatic artery proper and the gastroduodenal artery.  Gross anatomy Course The hepatic artery proper runs anterior to the portal vein and to the left ...
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Hepatic veins

The hepatic veins are three large intraparenchymal veins which drain the liver substance into the inferior vena cava (IVC), named the right hepatic vein, middle hepatic vein and left hepatic vein. The veins are important landmarks, running in between and hence defining the segments of the liver....
Article

Hepatobiliary system

The hepatobiliary system consists of the: liver biliary tree (both intra- and extra-hepatic) gallbladder The pancreas is included by some. 
Article

Hepatoduodenal ligament

Hepatoduodenal ligament is the peritoneal ligament of lesser omentum, which attaches the duodenum to the liver. Hepatoduodenal ligament contains: portal vein hepatic artery  common hepatic duct  part of cystic duct Hepatoduodenal ligament is a rout of spread of diseases of pancratic head t...
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Inferior pancreaticoduodenal artery

The inferior pancreaticoduodenal artery is the first branch of the superior mesenteric artery (SMA), though it often arises from the first jejunal branch. It anastomoses with branches of the superior pancreaticoduodenal artery (from the gastroduodenal artery) and it supplies the head of the pan...
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Left hepatic artery

The left hepatic artery (LHA) is formed when the proper hepatic artery (PHA) bifurcates. The hepatic arteries provide 25% of the blood supply and 50% of the oxygen supply to the liver. Gross anatomy The PHA bifurcates into the left and right hepatic arteries on reaching the porta hepatis. Thes...
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Left triangular ligament of the liver

The left triangular ligament is a peritoneal suspensory ligament of the liver. It is formed by the fusion of the superior and inferior reflections of the coronary ligament. It is shorter than the right triangular ligament and does not separate the left subphrenic space from the subhepatic space.
Article

Liver

The liver is the largest abdominal organ that plays a major role in metabolism and has a number of functions, including glycogen storage, decomposition of red blood cells, plasma protein synthesis, hormone production, and detoxification. It is one of very few organs that has the ability to regen...
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Meandering main pancreatic duct

Meandering main pancreatic duct (MMPD) comprises of a reverse Z-type and loop-type of pancreatic ducts. These ductal variants are found in ERCP and MRCP studies. The exact incidence is not known. Increased incidence of meandering pancreatic duct has been reported in patients with idiopathic re...
Article

Pancreas

The pancreas is a retroperitoneal organ that has both endocrine and exocrine functions: it is involved in the production of hormones (insulin, glucagon and somatostatin), and also involved in digestion by its production and secretion of pancreatic juice. Gross anatomy The pancreas can be divid...
Article

Pancreas divisum

Pancreas divisum represents a variation in pancreatic ductal anatomy that can be associated with abdominal pain and idiopathic pancreatitis. It is characterised, in the majority of cases, by the dorsal pancreatic duct (main pancreatic and Santorini ducts) directly entering the minor papilla with...
Article

Pancreatic duct diameter

The diameter of the (main) pancreatic duct is a commonly assessed parameter in imaging. Gross anatomy The duct diameter is greatest at the head and neck region and is slightly narrower towards the body and tail. Its normal reported value ranges between 1-3.5 mm 5, 8: head: 3.5 mm body: 2.5 m...
Article

Pancreatic ducts

The pancreatic ductal embryology is moderately complicated, leading to a number of anatomical variants of the pancreatic ducts, many of which are clinically significant. The normal arrangement is for the entire pancreas to be drained via a single duct, to the ampulla of Vater through the sphinc...
Article

Phrygian cap

Phrygian caps are the most common congenital anatomic variant of the gallbladder. It denotes folding of the fundus back upon the gallbladder body and is asymptomatic with no pathological significance. Radiographic findings A Phrygian cap may be identified in ultrasound, multiphase CT/MRI or in...
Article

Porta hepatis

The porta hepatis is a deep fissure in the inferior surface of the liver through which all the neurovascular structures (except hepatic veins) and hepatic ducts enter or leave the liver 1. It contains: right and left hepatic ducts right and left branches of hepatic artery portal vein From an...
Article

Portal vein

The portal vein (PV) (sometimes referred to as the main or hepatic portal vein) is the main vessel in the portal venous system and drains blood from the gastrointestinal tract and spleen to the liver. Gross anatomy The portal vein, usually measures approximately 8 cm in length in adults. It or...
Article

Posterior right subhepatic space

The posterior right subhepatic space (also known as the hepatorenal fossa or Morison's pouch) separates the liver from the right kidney. It is a potential space that is not filled with any fluid in normal conditions. Gross anatomy Posterior right subhepatic space is a subcompartment of the sup...
Article

Reticuloendothelial system

The reticuloendothelial system (RES) comprises of a number of tissues: spleen bone marrow liver Kupffer cells
Article

Riedel lobe

Riedel lobe is a common anatomical variant of the liver to be aware of because it can simulate a mass. Its misidentification as a pathologic abdominal mass has led to surgery. Pathology can also occur within it (e.g. malignancy or even torsion) and cause atypical hepatic symptoms low in the pel...
Article

Right hepatic artery

The right hepatic artery (RHA) is formed when the proper hepatic artery (PHA) bifurcates. The hepatic arteries provide 25% of the blood supply and 50% of the oxygen supply to the liver. Gross anatomy The PHA bifurcates into the right and left hepatic arteries on reaching the porta hepatis. The...
Article

Right subphrenic space

The right subphrenic space (a.k.a. right anterior space, right subdiaphragmatic space) is a potential space that lies between the right lobe of the liver and the inferior surface of the diaphragm. Gross anatomy This is a subcompartment of the supracolic compartment. It reaches as far as the up...
Article

Right triangular ligament of the liver

The right triangular ligament is a peritoneal suspensory ligament of the liver. It is formed by the fusion of the superior and inferior reflections of the right coronary ligament. It is longer than the left triangular ligament and compartmentalises the right subphrenic and subhepatic spaces.
Article

Rokitansky-Aschoff sinuses

Rokitansky-Aschoff sinuses are diverticula of the gallbladder wall which may be microscopic or macroscopic. Histologically, they are outpouchings of gallbladder mucosa that sit within the gallbladder muscle layer. Related pathology They are not of themselves considered abnormal, but may be ass...
Article

Solid and hollow abdominal viscera

The solid abdominal viscera is a collective term for those internal organs of the upper abdomen that are primarily solid in nature, namely the liver, pancreas, spleen, adrenals, and kidneys. It is used in contradistinction to the hollow abdominal viscera, which includes, the stomach, small bowel...
Article

Subvesical bile ducts

Subvesical/subvesicular bile ducts are variants of the biliary tree, and knowledge of these are important because they account for a significant portion of post-cholecystectomy bile leaks.  Terminology Cholecystohepatic ducts (usually segment V to the gallbladder) are commonly known as bile du...
Article

Supradiaphragmatic liver

Supradiaphragmatic liver has been reported as a very rare variant in liver morphology.  In this variant, liver tissue extends into the right hemithorax through an opening in the right hemidiaphragm. The tissue is connected to the right hepatic lobe by a pedicle. In one report, the caudate lobe ...
Article

Variant hepatic arterial anatomy

Variation in hepatic arterial anatomy is seen in 40-45% of people. Classic branching of the common hepatic artery from the coeliac artery, and the proper hepatic artery into right and left hepatic arteries to supply the entire liver, is seen in 55-60% of the population.  In general, the common ...
Article

Veins of Sappey

Veins of Sappey are small veins around the falciform ligament that drain the venous blood from the anterior part of the abdominal wall directly into the liver. This flow dilutes the portal perfusion at these sites, causing hepatic pseudolesions. Gross anatomy The superior vein of Sappey drains...
Article

Wandering spleen

Wandering spleen is a rare condition in which the spleen migrates from its usual anatomical position, commonly to the lower abdomen or pelvis. Epidemiology Wandering spleen is rare, with a reported incidence of <0.5%. Diagnosis is most commonly made between ages 20 and 40 and is more common i...

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