Flashcards in L6. Anatomy of the abdominal viscera: accessory organs Deck (30):
What two features must be present in order to call a surface a visceral surface in the abdominal cavity?
It must bear the imprint of adjacent structures and it must have the hilum
What is the liver? What are the surfaces of the liver and what demarcates them?
Why is this border clinically relevant?
Liver is a solid viscous with 2 surfaces (diaphragmatic and visceral) - demarcated by a sharp inferior border
Important clinically because enlarged liver is palpable here under the right costal margin.
Where is the liver located?
Right upper quadrant, related to right dome of diaphragm (the diaphragmatic surface is thus smooth
What structure projects past the inferior edge of the liver?
The tip of the gall bladder
Describe the lobar structure of the liver
Divided into 2 unequal lobes (right and left) by the falciform ligament.
What is the falciform ligament?
It is a peritoneal reflexion (smooth and shiny, serous membrane) and is a double layer that connects the diaphragmatic surface to the anterior abdominal wall.
There is a free interior edge to the ligament at the level of the umbilicus and it contains the ligamentum teres of the liver (fibrous cord that represents the obliterated umbilical vein which once carried blood from the placenta to foetus).
The surface of the liver is covered by peritoneum. Describe the superior part of the liver (from the ligamentum teres and falciform ligament)
The peritoneum reflects off the superior aspect of the liver and onto the under surface of the diaphragm - coronary ligament (reflexion of peritoneum).
Following the ligaments laterally, they become the right and left triangular ligaments.
The whole top of the liver is covered by peritoneum except one small bare area.
Describe the visceral surface of the liver
Visceral surface relates to the abdominal contents: bares impressions of the structures it relates to and also has the hilum (root) of the liver called the PORTA HEPATIS. Gastric impression on the left lobe seen.
It has a H shaped fissure
What lies in the important parts of the H shaped fissure on the visceral surface of the liver?
Cross piece being the porta hepatis (neurovascular and ducts entering and exiting).
Embedded in the grooves the right hand side is the gall bladder at the front and the IVC embedded into the groove behind.
On the left hand side on the H there are 2 fibrous structures grooving the liver: the ligamentum teres and falciform ligament and the ligamentum venosum (superiorly)
What is the ligamentum venosum?
Lies between the left lobe and the caudate lobe
An embryological remnant communicating with the left portal vein - it was once bringing oxygenated blood from umbilicus to the liver.
A shunt directly from left portal vein into the left hepatic vein and IVC - ductus venosum and is now the ligumentum venosum.
What are the four lobes of the liver seen from the visceral surface?
Caudate Lobe (between the IVC and the ligamentum venosum)
Quadrate Lobe (between the gall bladder and the falciform ligament)
What are the vessels running through the porta hepatis? What is their arrangement?
Portal vein behind, hepatic artery (to the left) and hepatic duct (to the right) in front.
Nerves and lymphatics scattered.
What is the caudate process?
Part of the caudate lobe sitting under the IVC that connects the caudate lobe to the right lobe
Describe the relationship between the lesser omentum of the stomach and the liver
There is peritoneal attachment between the lesser omentum and the liver (to the visceral aspect - porta hepatis).
What is important about the free edge of the lesser omentum? How is it formed?
The lesser omentum stops on the right side because the duodenum becomes retroperitoneal (dives back) and there is a resultant free edge of the lesser omentum.
The portal triad from the posterior wall to the porta hepatis by running in this free edge of the lesser omentum.
Describe the vascular input of the liver
The hepatic artery divides into right and left terminal branches for the two halves of the liver and enters the hilum.
The liver also gets blood from the portal vein, ascending and divides into right and left venous structure to enter the hilum.
Describe the venous drainage of the liver
Drained by hepatic veins (usually 3 in number) drains directly into the IVC (embedded into the visceral surface). Never see the veins outside the liver (can see the openings)
There is no venous drainage out of the porta hepatis
What is carried out of the duct coming out of the porta hepatis? Where does it go?
Bile is produced and secreted by liver cells and empties into ducts which get larger eventually forming the right and left hepatic ducts which join and form the common hepatic duct leaving the porta hepatis.
The gall bladder stores and concentrates the bile
Describe the path of the common hepatic duct down towards the duodenum
The duct descends in the free edge of the lesser omentum.
It transverses behind the first part of the duodenum and into the groove of formed by the pancreatic head
It passes behind the second part of the duodenum until they find the middle part of the vertical duodenum and opens into the wall
Describe the anatomy of the gall bladder
Pear shaped sac and divided into a FUNDUS (beyond inferior edge), BODY and NECK, which becomes continuous with the duct of the gall bladder: CYSTIC DUCT
Describe how the cystic duct of the gall bladder and the hepatic duct of the liver meet and then the pancreatic duct
The cystic duct lies over the front of the first part of the duodenum. And it eventually transverses to join the hepatic duct at which point it becomes the COMMON BILE DUCT.
The common bile duct eventually meets the major pancreatic duct and they form the main duct that empties into the Major papilla in the wall of the second part of the duodenum.
What surrounds the terminal portions of the hepatic and pancreatic ducts? What is important about this?
Smooth muscle surrounds the common opening where the 2 ducts have joined as well as the distal portion of the duct.
It forms a sphincter is that is normally closed (when digestion is not taking place) so that enzymes and bile don’t enter the system.
Thus bile backs up in the bile duct (accumulates) and then stored and concentrated in the gall bladder until is required.
Describe the location, shape and function of the pancreas
Pancreas is located centrally with its head surrounded by the duodenum and its tail projecting into the hilum of the spleen.
It is classically described as having a comma shape
Function: Important endocrine (eg. insulin) and exocrine functions (enzymes for digestion).
Describe the anatomy of the pancreas
Moving from Right to Left:
HEAD: in C shaped curve of the duodenum, and contains the uncinate process
NECK: runs over the top of the superior mesenteric vessels
BODY: is above the duodenojejunal flexure (DJF)
TAIL: runs across to the left hand side and is directly at the hilum of the spleen
What is the uncinate process of the head of the pancreas?
It is a wedge shaped projection off the head and lies posterior to the superior mesenteric vessels (which cross over the duodenum and this process).
It is also related to the third part of the duodenum
Describe the pancreatic duct(s)
It transverses from the tail of the pancreas collecting pancreatic enzymes, gets larger as it transverses and joins the common bile duct and enters the main duodenum papilla.
The second, smaller pancreatic duct drains the distal portion of the head and uncinate process, crossing the major duct and enters the duodenum. This duct has no relationship or interaction with the bile duct
What is the spleen?
Oval shaped mass of lymphoid tissue, about the size of a clenched fist (variable) - they get smaller in the elderly population.
The whole thing is incredibly vascular: damage = bleeding
Where is the notched border of the spleen and what does it represent?
Notched border of the spleen - the border that divides the smooth diaphragmatic surface from the visceral surface (which has hilum and imprints)
It represents evolutionary processes (non-complex species have multiple spleens, stipulated humans once had this arrangement)
Is there a duct running through the hilum of the spleen?
There is no duct to the spleen, the hilum contains only neurovascular and lymphatic structures