APC3 Flashcards
Where is the liver positioned?
Occupies most of right hypochondrium, extends through epigastrium –> left hypochondrium
Most under ribs and costal cartilages
Contact with inferior surface of diaphragm
How does the liver develop? How is its position maintained
Between the two layers of ventral mesogastrium of the embryo
Although liver connected to adjacent structures by peritoneum - not its main support
Maintained by attachment of HEPATIC VEINS which drain blood to IVC posteriorly
In many instances inferior vena cava embedded in liver tissue, other times hepatic veins will run short extra-hepatic course
Surface anatomy of liver?
Markings relatively constant in healthy individuals, but can change considerably in disease states
1) Right upper limit: upper margin right 5th rib, mid-clav line
2) Midpoint superior surface: junction of xiphoid & body of sternum
3) Lower margin of left 5th rib, mid-clav line
4) Right lower: close to lowest point of right costal margin
5) : between upper and lower right limits (1+4)
What is the H shape of the liver?
5 important structures of visceral surface of liver
1) Gall bladder anteriorly, IVC posteriorly
2) Hilum of liver (vessels enter, ducts leave) - porta hepatic
3) Falciform ligament anteriorly, attachment of lesser omentum posteriorly
(double layers of peritoneum, remnants of ventral mesograstrium [caudal foregut –> AAW] and associated embryological remnants)
What is the liver invested by?
Peritoneum derived from ventral mesogastrium
Reflected onto adjacent structures at certain points
Describe the lines of peritoneal reflection on the liver
Starting at inferior surface - ANTERIOR LIMB of LEFT CORONARY LIGAMENT -> peritoneum would be reflected off the liver and onto undersurface of diaphragm in continuity with parietal peritoneum
Line moves towards ANTERIOR surface where becomes one layer of the FALCIFORM LIGAMENT which projects onto AAW as far as umbilicus
Right layer of falciform ligament continues with UPPER/ANTERIOR layer of CORONARY LIGAMENT - continues as UPPER LIMB of RIGHT TRIANGULAR ligament
Lower limb of RIGHT TRIANGULAR ligament continues obliquely as the LOWER/POSTERIOR layer of the CORONARY ligament (space enclosed by two ligaments = BARE AREA - no peritoneum)
Right triangular and coronary ligaments reflected onto DIAPHRAGM and PAW
Peritoneal line of reflexion anterior to IVC –> posterior layer of ROOT of LESSER OMENTUM -> continuous with porta hepatis (partly enclosed by peritoneum which is continuous with POSTERIOR layer of ROOT of lesser omentum)
Posterior layer continuous with POSTERIOR LIMB of LEFT TRIANGULAR LIGAMENT
Reminder: learn liver histology
!
What is the ductus venosus?
Connects porta hepatis to IVC (oxygenated blood from umbilical vein –> hepatic portal vein)
Ductus venous allows oxygenated blood to bypass hepatic circulation and go to systemic circulation rapidly by going straight to IVC
Soon after birth umbilical vein and ductus venosus undergo fibrosis and close
What is ligamentum teres?
Lies within free edge of falciform ligament, connecting porta hepatis superiorly with umbilicus inferiorly
What is the ligamentum venosum?
Lies between hepatic portal vein at porta hepatis and inferior vena cava - enclosed within the root of the lesser omentum
How can the liver be anatomically divided?
Right and left lobes marked by sagittal plane through falciform ligament and fissures for ligamentum teres and ligamentum venosum
Right lobe - two smaller parts: caudate and quadrate lobes
Caudate: between IVC and fissure for ligamentum venous
Quadrate: between gall bladder bed and ligamentem teres
What are the subphrenic spaces?
ANTERIOR subphrenic recess
Formed by peritoneal attachment of liver to diaphragm
Right and left spaces either side of falciform ligament (where peritoneum reflected off posterior liver onto diaphragm)
What is the hepatorenal pouch?
The right posterior subphrenic space
Superior to retroperitoneal kidney - posterior to right anatomical lobe of liver where peritoneum is being reflected onto diaphragm
Important clinically as a site of fluid collection (so is the rectovesical/rectouterine pouch)
Which areas of abdominopelvic cavity will leakage gravitate (GI tract rupture) in supine and seated position? Where would pain be felt if leakage was irritant?
Supine: Hepatorenal pouch (right posterior subphrenic space) and rectovesical/rectouterine pouch
Seated: ?
Pain: ?
What organs is the liver related to?
In life, posture and movements of respiration may affect relationships of liver
Visceral surface of right lobe of the liver is related to the right suprarenal gland, right kidney and transverse colon
Visceral surface of left lobe in contact with stomach and oesophagus
What is the common hepatic artery?
Branch of celiac, follows retroperitoneal course to the right, towards superior (first) part of duodenum
At this point, splits to become hepatic artery proper and gastroduodenal artery
What is the hepatic artery proper?
(from common hepatic)
Enters mesentery of initial part of duodenum, then curves upwards between the 2 layers of the free edge of the lesser omentum with the BILE DUCT and HEPATIC PORTAL VEIN to liver
Gives off right gastric artery
On reach porta hepatis - divides into right and left branches supplying physiogical/functional lobes
Hepatic artery delivers about 20% of blood reaching the liver
What is the gastroduodenal artery?
(from hepatic artery)
Passes inferiorly behind superior/first part of duodenum along with the bile duct and the hepatic portal vein
Arising from gastroduodenal artery –> RIGHT GASTROEPIPLOIC and SUPERIOR PANCREATICODUODENAL
What are hepatic veins and how are they formed? (venous drainage of liver)
Blood in SINUSOIDS drains to CENTRAL VEINS of liver lobules –> unit to larger veins –> eventually MAIN HEPATIC veins which drain all blood from liver into IVC
Usually 3 - often completely embedded in liver tissue along with IVC
Devoid of valves
Pattern of venous drainage not closely related to physiological lobes of the liver - (those lobes are defined by branches of the hepatic artery / hepatic portal vein )
What is the hepatic portal vein?
Drains venous blood from GI tract, between lower part of oesophagus and upper part of anal canal - and associated organs
Contains products of digestion and ~80% of blood brought to liver –> neither HPV or its tributaries contain vein
Formed behind NECK of pancreas by union of SUPERIOR MESENTERIC vein and SPLENIC vein (splenic receives inferior mesenteric initially - IM drains all hindgut structures to splenic vein and SM drains midgut/caecum)
Travels behind 1st part duodenum and here enters free margin of lesser omentum to eventually reach porta hepatis where divides into right and left branches (supplies right and left physiological lobes)
Venous drainage of oesophagus when considering portal hypertension?
In normal conditions: anastomoses closed, but where obstruction of hepatic portal vein e.g. tumours or cirrhosis - communications may be opened up –> varicosities oesophageal varices
What are porto-systemic anastomoses?
Sites within GI tract where venous blood from viscera drains to systemic circulation (back to heart) as well as to the portal system:
Lower end of oesophagus: tributaries of left gastric vein (portal) connect with oesophageal tributaries of the azygos or accessory hemiazygos veins (systemic)
In normal conditions: anastomoses closed, but where obstruction of hepatic portal vein e.g. tumours or cirrhosis - communications may be opened up –> varicosities (oesophageal varices)
Also found at wall of anal canal, umbilicus, & sites where viscera are in contact with the abdominal wall, such as retroperitoneal areas of colon and the bare area of the liver
What is the hepatic artery related to?
Peritoneum of PAW, duodenum and lesser omentum
What is the nerve supply of the liver?
Most pass via porta hepatis, though some fibres pass into the substance of the liver via its peritoneal attachments
SYMPATHETIC nerve fibres supplying from CELIAC GANGLIA enter porta hepatis along the walls of the hepatic ARTERY - principally concerned with vasomotor activity of the branches of the hepatic artery within the liver parenchyma - afferent PAIN impulses may also travel with sympathetic nerves
PARASYMPATHETIC derived from ANTERIOR and POSTERIOR VAGAL TRUNKS - ANTERIOR trunk carries fibres from both vagus nerves and passes to PORTA HEPATIS between two layers of lesser omentum
(function not clear)
