Lesson12, The Liver, MMed Anatomy, Imaging

Lesson12, The Liver, MMed Anatomy, Imaging

Clinical

v  Liver biopsy Hepatic tissue may be obtained for diagnostic purposes by liver biopsy. The needle puncture is commonly made through the right 10^th intercostal space in the midaxillary line. Before the physician takes the biopsy, the person is asked to hold his breath in full expiration  to reduce the costodiaphragmatic recess and to lessen the possibility of damaging the lung and contaminating the pleural cavity.

v  Liver Coronary Ligaments to Diaphragm. The three parts of the coronary ligaments are attached to the diaphragm, except the inferior Vena Cava, suprarenal gland and kidney intervene.

v  Function of the Liver:

Ø  with the exception of lipids, every substance absorbed by the alimentary tract is received first by the liver, via hepatic portal vein.

Ø  liver stores glycogen and secretes bile

v  Cirrhosis of the liver: there is progressive destruction of hepatocytes in cirrhosis of the liver and replacement by fibrous tissue. This tissue surrounds the intrahepatic blood vessels and bile ducts, making the liver firm and impeding circulation of blood through it.

v  Hepatic Segmentation. Since the right and left hepatic arteries and ducts and branches do not communicate, it is possible to perform hepatic lobectomies (removal of the right or left lobe of the liver) and segmentectomies. There are 7 segments. Grant p151.

v  Portal triad:

v  Portosystemic Shunt: A Common method for reducing portal hypertension is to divert blood from the portal venous system to the systemic venous system by creating a communication between the portal vein and the IVC. This portacaval anastomoses of portosystemic  shunt may be created where these vessels lie close to each other

Ø  posterior to the liver.

Ø  Note the proximity of the splenic vein and the left renal vein, enabling a splenorenal shunt to be established surgically to relieve portal hypertension. The splenorenal ligament containing splenic artery and vein.

v  Vessels in potal triad Grants p153

v  ERCP. Endoscopic Retrograde Cholangiography and Pancreatography demonstrates the bile and pancreatic ducts.

Ø   Left and right hepatic ducts collect bile from the liver. Common hepatic duct hepatic duct unites with the cystic duct superior to the duodenum to form the Bile Duct. The Bile Duct descends posterior to the superior duodenum (1^st part of the duodenum). The bile duct joins the main pancreatic duct to form the hepatopancreatic ampulla which opens in the duodenal papilla. This passage is the narrowest part of the biliary passages and is the common site for impaction of gallstones.  Gallstones may produce biliary colic (pain in the epigastric region).

Ø  Endoscopic retrograde cholangiography is done by first passing a fiberoptic endoscope through the mouth, esophagus, and stomach. Then the duodenum is entered  and a canicula is inserted into the major  duodenal papilla and is advanced under fluoroscopic control into the duct of choice (bile duct or pancreatic duct) for injection of contrast medium.

v  Developmental variability of the pancreatic ducts p157

v  Variations in Hepatic and Cystic Arteries p158

v  Variations of cystic and hepatic ducts and gallbladder.

Portal hypertension, Cirrhosis: Portocarval system

1.       Esophageal veins Azygos veins (systemic) and the left gastric vein (portal)

a.       Esophgeal varices can be seen through endoscopy

2.       Inferior and Middle Rectal Veins drain into the IVC (Systemic) and Superior Rectal Vein continuing as the inferior mesenteric vein (Portal)

a.       Hemorrhoids result of the vessels are dilated

3.       Small epigastric veins (systemic) and Periumbilical Veins (Portal)

a.       Radiate varicose from “caput madusae”

4.       Systemic Retroperitoneal veins (Systemic) with twigs of Colic Veins (portal)

Left renal vein

v  Drains the left testis, left suprarenal gland and left kidney. Renal arteries are posterior to the renal veins.

Ureter

v  Ureter crosses the external iliac artery just beyond the common iliac bifurcation.

v  Testicular arteries cross anterior to the ureter and join the ductus deferens to deep inguinal ring.

Pyelogram: Identify the following structures

v  12^th Rib                         Major Calyx                        Minor Calyx                        Renal Pelvis

v  Ureter                          Gas in Intestine                                Sacrum                                 Ureter

v  Catheter in bladder

v  Note the renal papilla bulging into the minor calices, which empty into the major calyx that open into the renal pelvis drained by the ureter.

Renal Transplantation: is an established for chronic renal failure. Remove the kidney without damaging the suprarenal gland. The site of transplanting the kidney is in the iliac fossa of the greater fossa. The renal artery and vein are joined to the external iliac artery and vein and the ureter is sutured into the bladder.

Kidney Structure:

v  Superior and inferior pole. Vessels enter the renal sinus and the superior and inferior renal pole.

v  Adult polycystic disease is an important cause of chronic renal failure.

Anomalies of Kidney and ureter

v  Bifid pelvis

v  Duplicated or bifid ureters

Ø  Complete or incomplete. Unilateral or Bilateral

v  Retrocaval ureter. The ureter courses posterior then anterior to the inferior vena cava

v  Horseshoe kidney. The right and left kidneys are fused in the midline

v  Ectopic pelvic kidney. Pelvic Kidneys have no fatty capsule and can be unilateral or bilateral. Obstructed or injured during labour.