Liver Flashcards
Where is the liver located?
Right hypochondriac (right lobe), epigastric, and left hypochondriac (left lobe)
What are the functions of the liver?
- Carbohydrate, lipid, and amino acid metabolism
- Inactivation of drugs
- Synthesis and secretion of bile
- Detoxification
- Lymph production
- Blood reservoir
- Storage of vitamins and minerals
- Removal of waste
What divides the left and right lobes of the liver?
- IVC
- Middle hepatic vein, cranially
- Falciform ligament, at the diaphragmatic surface
- Main lobar fissure, caudally
- Gallbladder (within main lobar fissure)
Where does the main lobar fissure extend from?
From right portal vein to the gallbladder
What is the falciform ligament?
The extra-hepatic part of the ligamentum teres; divides the left and right lobes of the liver
What does the falciform ligament connect?
Connects the liver to the anterior abdominal wall and to the diaphragm with the ligamentum teres at its free edge
Do we normally see the falciform ligament on ultrasound?
No, unless the patient has ascites
What is the ligamentum teres?
“Round ligament”. Remnant of fetal umbilical vein (closes after birth); divides the medial from lateral segment of the left lobe
What is the ligamentum teres an extension of?
The left portal vein
The fetal umbilical vein normally closes after birth, but in which case would it recanalize?
Cirrhosis or portal hypertension
How does the ligamentum teres appear on ultrasound?
An echogenic, triangular spot transversely
What is the ligamentum venosum?
Remnant of fetal ductal venosum; separates left lobe anteriorly from caudate lobe posteriorly
How do the ligamentum teres and venosum communicate?
At level of portal vein
How many lobes are there in the liver?
3; right, left, caudate
What is the main lobar fissure?
“Interlobar fissure”; divides left and right lobes caudally
Where does the main lobar fissure extend from?
From right portal vein to the gallbladder
What does the left portal vein divide?
Anterior left lobe from posterior caudate lobe
What is the caudate lobe?
Smallest lobe with its own bile ducts and blood supply, emptying from its posterior aspect directly into IVC
What binds the caudate lobe?
Ligamentum venosum anteriorly and posteriorly by IVC
Which veins are joined by the ligamentum venosum?
Left hepatic and left portal veins
Whats the normal size of the liver?
16cm, maybe 17cm if the patient is very tall
What is it called when the liver is enlarged?
Hepatomegaly
What is the capsule which covers the liver?
Glisson’s capsule
Do we see the main lobar fissure on ultrasound?
Yes, as a thin echogenic line extending from the right portal vein to the gallbladder fossa sagittally
What is the porta hepatis?
AKA Portal triad; Fissure through which the portal vein + hepatic artery enter the liver and the common bile duct exits the liver
Where does the porta hepatis lie in the liver?
On the inferior surface of the right lobe
How does porta hepatis look on ultrasound?
Sag: “Shotgun” sign
TRV: “Mickey mouse”
What supplies blood to the liver?
Hepatic artery (20%) and portal vein (80%)
What drains blood from the liver?
The 3 hepatic veins (right, middle, left) which will drain into the IVC
How do the hepatic veins lie?
Sagittally
Where does the caudate lobe receive its blood supply from?
From both right and left portal radicals in addition to hepatic arterial branches
Describe the branches of the celiac axis.
Celiac trunk gives rise to COMMON HEPATIC ARTERY and SPLENIC ARTERY
CHA gives rise to GASTRODUODENAL ARTERY, SUPRADUODENAL ARTERY, and RIGHT GASTRIC ARTERY
How does the common hepatic artery supply blood to the liver?
It branches off into right and left branches which supply the right and left lobes, respectively
What do the portal veins supply to the liver?
Nutrient-rich blood from the intestines
Describe where the main portal vein originates and its branching.
- The splenic vein and superior mesenteric vein unite to form the MPV before entering the liver (this is known as the portal-splenic confluence)
- At the porta hepatis, MPV divides into right and left portal veins
Describe the branching of the left and right portal veins in the liver.
- The left portal vein travels sagittally into the left lobe to branch into MEDIAL and LATERAL branches
- The right portal vein travels transversely into the right lobe to branch into ANTERIOR and POSTERIOR branches
How do bile ducts and portal veins travel in relation to one another?
Parallel (seen as shotgun sign/double barrel sign in sagittal view)
What is the best view to visualize the hepatic veins?
TRV at the cephalic portion (dome) of the liver
Which of the hepatic veins join together prior to draining into the IVC?
Middle and left
Where are each of the hepatic veins located and which portions of the liver do they divide?
- Right hepatic vein: within right intersegmental fissure, divides right lobe into ANTERIOR and POSTERIOR segments
- Middle hepatic vein: within main lobar fissure, divides liver into right and left lobes
- Left hepatic vein: within left intersegmental fissure, divides left lobe into MEDIAL and LATERAL segments
What are some of the ways we are able to differentiate between the hepatic and portal veins?
- Collagen content: portal veins have more collagen in their walls (brighter) vs hepatic veins that have less collagen in their walls (not as bright)
- Branching pattern: portal veins travel transversely, hepatic veins travel sagittally
- Caliber changes: the diameter of portal vein doesn’t change, but hepatic veins will increase in diameter as they come closer to the IVC
- Segmental location: portal veins located within segments (intrasegmental), while hepatic veins located between segments (intersegmental)
- Doppler characteristics: portal vein with continuous signal, hepatic veins with pulsatile signal
What do the superior and inferior mesenteric veins drain?
SMV: small intestine
IMV: large intestine
What does the splenic vein drain?
Spleen
