Anatomy Lecture 4 -- Solid Organs Flashcards
3 solid organs of the abdomen
- Spleen
- Pancreas
- Liver/ Gall bladder
Define the 1x3x5x7x8x9x11 rule
Anatomical proportions of the spleen
- SIZE = 1” x 3” x 5”
- WEIGHT = ~7 oz
- Position = between 9th and 11th ribs
Define the precise location of the spleen
- Between the 9th and 11th ribs
- Left hand side
- Between the stomach and splenic flexure of the colon (anteriorly) and the diaphragm (posteriorly)
- In left hypochondriac region
From what do peritoneal reflections of the spleen develop?
Primitive dorsal mesentery
Describe the relationships of the spleen during the primitive embryonic stage
Located in the dorsal mesentery, which is perfectly in the dorsal midline between the aorta and the developing stomach
Ligaments connected to the spleen
- Splenorenal ligament
- Gastrosplenic ligament
- Phrenicocolic ligament (diaphragm to splenic flexure; spleen rests on it but is not connected by it)
Surfaces of the spleen
- Diaphragmatic surface
- Visceral surface:
- Gastric
- Renal
- Colic
What organs are related to the spleen by the gastric impression
Posterior left side of the stomach and tail of the pancreas
Organs related to the spleen by the renal impression
Upper, left anterior surface of the left kidney
Organs related to the spleen by the colic impression
Splenic flexure of the colon
Blood supply of the spleen
Splenic artery
Splenic vein
Describe the location of the splenic artery
- From the celiac trunk
- Larger, tortuous – posterior to the lesser sac and along the superior border of the pancreas
- Travels through the lienorenal ligament to the spleen
Function of the splenic artery
Provide blood supply to the stomach (short gastric and left gastroepiploic arteries via the gastrosplenic ligament) and the spleen
Describe the location of the splenic vein
- Travels on the posterior surface of the pancreas, below the artery
- Joins with the superior mesenteric vein to form the portal vein
- Usually receives the inferior mesenteric vein behind the body of the pancreas
Common cause of splenomegaly
- Usualyl associated with increased workload (i.e. hemolytic anemias) –> response to hyperfunction
- Therefore associated with any disease process that involves abnormal RBCs being destroyed in the spleen
2 common causes of splenomegaly unrelated to function
- Congestion due to portal hypertension
- Infiltration by leukemias and lymphomas
Treatment of splenomegaly
Removal (without any apparent ill effects)
4 functions of the spleen
- Storage of RBCs
- Destruction of worn-out RBCs
- Removal of foreign material from the blood
- Production of mononuclear leukocytes
COnsequence of losing one’s spleen
Not essential to life; liver and bone marrow can take over many of its functions = no apparent ill effects
5 parts of the pancreas
- Head
- Neck
- Body
- Tail
Describe the anatomical position of the pancreas head
- Lies within the medial curve of the D2
- Uncinate process elongation of inferior border to the left, crossed anteriorly by the superior mesenteric vessels
- Posterior = IVC and bile duct
Describe the anatomical position of the pancreas neck
- Left of the head
- Superior = pylorus and origin of the celiac trunk
- Posterior = origin of the portal vein
Describe the anatomical position of the pancreas body
- Anterior = lesser sac, then stomach
- Posterior = aorta, splenic vein and left kidney
- Inferior = duodenal-jejunal junction
- Superior = splenic artery
Describe the anatomical position of the pancreas tail
- Left extremity
- Extends to the hilum of the spleen in the lienorenal ligament
Define the ducts associated with the pancreas
- Common bile duct (from liver and gall bladder)
- Main pancreatic duct (of Wirsung)
- Both join into the hepatopancreatic ampulla (ampulla of Vater)
Sphincter associated with the pancreas
Sphincter of Oddi (or sphincter of ampulla)
Define the sphincter of Oddi
A muscular valve that controls the flow of digestive juices (bile and pancreatic juice) through the ampulla of Vater into the second part of the duodenum
Normal variation of the pancreatic ducts
Most people have one, but an additional accessory duct can occur = Duct of Santorini
Where does the duct of Santorini empty to?
Straight to the duodenum at the minor duodenal papilla
Draw out the blood supply of the pancreas
Parts of the diaphragmatic surface of the liver (10)
Parts of the visceral surface of the liver (12)
Lobes of the liver
- Right lobe
- Left lobe
- Quadrate lobe
- Caudate lobe
Number of functional segments of the liver
8
What delineates each functional segment of the liver
- Hepatic veins at the periphery of each segment
- Center has branches of the portal veins, hepatic arteries and bile ducts
2 ways to divide the lobes of the liver
Anatomical lobes
Functional lobes
How to delineate anatomical lobes
Divide along the left-hand limb of the “H” and by the attachment of the falciform ligament on the diaphragmatic surface
How to delineate functional lobes of the liver
Separated by a plane through the right hand limb of the “H” from the gall bladder to the sulcus of the inferior vena cava – defined by ductal and vascular anatomy
Function of the gall bladder
Store bile
3 parts of the gall bladder
- Fundus
- Body
- Neck
Valve of the gall bladder
Spiral folds
Function of gall bladder spiral folds
Kelp keep the cystic duct open so bile can easily be diverted into the gall bladder when the distal end of the bile duct is closed by the sphincter of the bile duct of the hepatopancreatic duct
Structures in the hepatoduodenal ligament
- Proper hepatic artery
- Portal vein
- Bile duct
Blood supply of the gall bladder (6 structures)
Blood supply of the liver
IVC, 3 hepatic veins, hepatic artery, portal vein
4 major veins of the portal system
- Portal vein
- Splenic vein
- Inferior mesenteric vein
- Superior mesenteric vein
4 major vein types of the caval system
- 11 intercostal veins
- 1 subcostal vein (T12)
- 4 lumber veins
- Hepatic veins
Define portocaval anastomoses
Areas where the veins of the portal and caval systems meet
4 types of portocaval anastomoses
- Esophageal
- Paraumbilical
- Rectal
- Retroperitoneal
Define paraumbilical veins
Small veins in the course of ligamentum teres and the medium umbilical ligament
Define portocaval hypertension
High blood pressure in the portal vein system caused by liver disease
Cause of consequences of portal hypertension
Blood being forced down alternate channels (esophageal and anorectal varices, or paraumbilical veins) by the increased resistance to flow through the systemic system rather than the portal system
Parasympathetic innervation of the GIT
- Vagus nerve
- Pelvic splanchnic nerves
What does the vagus nerve innervate?
- Esophagus to the end of the proximal 2/3 of the transverse colon
- (This is the point of the midgut/hindgut junction – occurs just before the splenic flexure of the transverse colon)
What do the pelvic splanchinic nerves innervate?
Distal 1/3 of the transverse colon to the rectum
Sympathetic innervation of the GIT
- Thoracic splanchnic nerves
- Lumbar splanchnic nerves
List the thoarcic splanchnic nerves
- Greater splanchnic nerve (T5 - 9)
- Lesser splanchnic nerve (T9-10)
- Lowest (least) splanchnic nerve (T12)
Origin of lumbar splanchnic nerves
L1 - 2
Location of sympathetic synapses for GIT
In the aortic, superior mesenteric or inferior mesenteric plexuses. Then, post-ganglionic fibers use the vessels to get to the organs
Location of synapses for the parasympathetic innervation of the GIT
Pre-ganglionic fibers use the vessles to get to the organs AND THEN synapse in the wall of the organs
NOTE: No parasympathetic innervation for the spleen
How does the right vagus nerve enter the abdomen?
Through the esophageal hiatus of the diaphragm as the posterior vagal trunk
How does the left vagus nerve enter the abdomen?
Through the esophageal hiatus of the diaphragm as the anterior vagal trunk
