Gut Book 3: Supracolic Compartment: Esophagus, Stomach, Spleen, Liver, Pancreas Flashcards
Supracolic compartment definition
peritonealized area between the thoracoabdominal diaphragm and the transverse colon and its associated mesocolon
Supracolic compartment contents
Contains the distal esophagus, stomach, spleen, liver, gall bladder, and part one of the duodenum
Discuss the transverse mesocolon’s categorization
Since the transverse mesocolon straddles the pancreas, it is retroperitoneal and not in either the supra or infracolic compartment.
Subdivision of the supracolic compartment
by the lesser omentum, thereby forming the omental bursa.
Esophagus origin
begins at the cricoid cartilage opposite CV6
Esophagus muscular composition
outer longitudinal, inner circular smooth muscle
Clinical Correlation: Zenker’s diverticulum
The upper 1/3 (approx) of the esophagus is composed of striated muscle continuous with the inferior constrictor and innervated by the recurrent laryngeal nn. Weakness sometimes occurs in the area of the posterior pharyngo-esophageal junction. Because fibers of the inferior portion of the inferior constrictor (cricopharyngeus/ upper esophageal sphincter) diverge, a small area is left where the mucosa and adventitia can be directly opposed without intervening muscle fiber. An out-pocketing of these two opposed layers can occur, referred to as a Zenker’s diverticulum, which gathers food, fills the retrovisceral/ retroesophageal space and impedes swallowing.
Esophagus: course
neck: slightly to the left of the midline upper thorax (TV4): midline middle thorax (TV8): crosses to the left (anterior to aorta) lower thorax (TV10): left of the midline to penetrate the diaphragm
Esophagus: sites of potential constriction
1- at the junction of the pharynx and esophagus, cricopharyngeus m. (upper esophageal sphincter)
2- aortic arch
3- left primary bronchus
4- esophageal hiatus
Where does the esophagus pierce the diaphragm?
level of the 10th thoracic vertebra.
Esophagus attached to the margins of the esophageal hiatus via…
the phrenico-esophageal ligament (dorsal mesentery). It attaches to the esophagus both superior and inferior to the hiatus, allowing independent movement of the esophagus and diaphragm during breathing.
2 common types of hiatal (esophageal) herniation
sliding and paraesophageal
sliding hiatal herniation
due to elongation of the mesenteric attachments of the esophagus to the diaphragm a portion of the lesser curvature and fundus “slide” through the esophageal hiatus into the thoracic cavity; the gastro-esophageal junction (cardia) will be located superior to the diaphragm; associated with “heartburn.”
paraesophageal hiatal herniation
protrusion of the fundus of the stomach through a defect in the diaphragm next to the esophagus; the gastro-esophageal junction (cardia) remains INFERIOR to the diaphragm– this is more dangerous than the sliding one as the fundus may strangulate.
Abdominal course of esophagus
approximately 2.5 cm in length
only peritonealized portion (mesoesophagus)
joins cardiac portion of stomach at approximately the level of the 11th thoracic vertebra
Gastro-esophageal junction (borders)
Right border– continuous with the lesser curvature of the stomach
left border- separated from the fundus of the stomach by the cardiac notch
Esophageal mucosa
demonstrates an epithelial transitional zone (stratified squamous to simple columnar, aka, “Z” line)
Lower esophageal sphincter
Although not anatomic, a functional physiologic sphincter exists at the esophageal cardiac junction (L.E.S.- lower esophageal sphincter) which appears to be important in regulating the entrance of food into the stomach and in preventing esophageal reflux.
Arterial supply to the esophagus
- cervical portion: inferior thyroid a.
- thoracic portion: branches from the bronchial aa. & from the aorta directly
- abdominal portion: esophageal branch of the left gastric a.
Venous drainage of the esophagus
- esophageal submucosal veins are drained by venae comitantes of the arterial supply.
- These veins drain to systemic (brachiocephalic and azygos vv.), and viscera venous systems (portal vein)
Esophageal varices
Reversal of venous drainage due to circulatory blockage within the liver causes distension of the esophageal submucosal veins, resulting in the formation of esophageal varices which over time can rupture causing death.
GERD (Gastroesophageal reflux disease)
produces “heartburn” (pyrosis)- referred pain is to the substernal region, made worse by sliding hiatal hernia.
Stomach- function and shape
First organ of digestion; mixes food with digestive juices
Typically J-shaped, however, shape varies with stature and content
Stomach: fastening
Fastened securely to the diaphragm superiorly (TV11) via the gastrophrenic ligament; inferiorly to the posterior body wall via its continuity with the retroperitoneal portion of the duodenum (LV1-LV2)
Mobility of stomach
Since the remainder of the stomach is only loosely secured by the omenta (greater and lesser), it is highly mobile, so much so, that when sufficiently filled may extend into the major pelvis.
Stomach: external structure: curvatures
Greater: convex lateral border
lesser: concave medial border
Stomach: external structure: notches
- Cardiac: notch between junction of esophagus and fundus
2. angular incisure: sharp angulation of lesser curvature at the junction of body and pyloric portion
Stomach: external structure: regions
Cardia- indefinite area around esophageal entrance
Fundus- portion more superior than cardia
Body- area between fundus and pyloric antrum
Pyloric portion:
pyloric antrum- expanded portion proximal to pyloric canal
pyloric canal
pylorus: thickened muscular portion forming sphincter between stomach and duodenum, located to the right of the midline at LV1-LV2
Congenital Hypertrophic Pyloric Stenosis
1-4/1000 live births; 4:1 male/ female- grossly increased muscle layer (mainly circular) at the pylorus which does not open enough to pass stomach contents. It is palpable in the right upper quadrant just to the right of the midline and is usually identified in the first 3-6 weeks of life after episodes of progressive vomiting; can be surgically dilated.
Stomach: muscular wall
- outer longitudinal
- inner circular: greatly thickened segment of which forms the PYLORIC SPHINCTER
- innermost oblique: modified circular fibers often forming an incomplete layer
Stomach: internal: mucosa
- When the muscular layers are contracted the mucosa displays longitudinally oriented folds called RUGAE (Magenstrassen- stomach streets)
- Located predominantly along the lesser curvature; forms GASTRIC CANAL (temporarily visible during swallowing)
Stomach relations/ contact areas: anterior
a. anterior abdominal wall
b. diaphragm
c. left lobe of the liver
Stomach relations/ contact areas: superior
diaphragm
Stomach relations/ contact areas: posteriorly and inferiorly
referred to as the STOMACH BED- area related to the stomach that directly cradles it, including retroperitoneal structures behind the posterior wall of the omental bursa.
a. left hemidiaphragm
b. spleen
c. body and tail of pancreas
d. Superior pole of left kidney
e. left suprarenal gland
f. splenic artery
g. transverse colon & transverse mesocolon
h. left colic flexure
gastric/ peptic ulcer
Erosion of the posterior wall of the stomach due to gastric/ peptic ulcer can erode into ANY of the above structures. Erosion of the splenic a. as it courses through the substance of the pancreas can result in severe hemorrhage, pancreatitis, and peritonitis.
Spleen: function
largest single mass of lymphatic tissue in the body.
a. reservoir of red and white cells
b. removes old RBCs and waste products
c. Elaborates lymphocytes (immune surveillance & response)
Spleen as emergency resource (clinical note)
The spleen can expel its reservoir of blood in time of need, i.e. decreased volume or increased demand, through contraction of smooth muscle located in the capsule.
Spleen: location
the left upper quadrant within the dorsal mesentery suspended between the greater curvature of the stomach (gastrosplenic ligament) and the diaphragm (phrenicolienal ligament) at ribs 9, 10, 11. Also, the spleen rests on the phrenicocolic ligament (sustentaculum lienis: shelf for the spleen).
spleen palpation and splenomegaly (clinical note)
The spleen normally does not extend inferior to the costal margin and therefor is not palpable through the abdominal wall– needs to be at least 3X normal size to palpate.
Spleen: size and shape
Normal weight range 100-250 gm
Wedge shaped or tetrahedral, shape depending on:
- distribution of vessels within
- fullness of surrounding organs, i.e. stomach, transverse colon
Spleen surfaces
a. lateral surface: smooth and convex
b. medial surface: triangular and somewhat concave; location of hilum
d. Apex: directed superiorly and medialward
d. Base: inferior
Spleen: relations/ contact areas
- Medial: displays gastric, renal and colic impressions; tail of pancreas contacts hilum
- lateral: contacts diaphragm inferior & medial to the costodiaphragmatic recess
- Inferior: base rests on phrenicocolic ligament (sustentaculum lienis- L. to prop, to hold upright)
Accessory spleen
usually small: .5-2.5 cm
most often located in gastrosplenic ligament near hilum; can be found in tail of pancreas, mesentery proper, in proximity to the ovary or testes
Splenic rupture/ splenectomy
most frequently injured organ in the abdomen
susceptible to direct compression, laceration from broken ribs, blunt trauma elevating intra-abdominal pressure resulting in capsular rupture
Capsule can be sutured; if injured too severely, SPLENECTOMY is performed to prevent fatal bleeding. Adults tolerate splenectomy well since the liver and bone marrow can assume the spleen’s functions
A splenectomy can also be performed as a result of splenomegaly due to hypertension and various leukemias and anemias where the spleen becomes engorged & clogged due to increased white cell production or increased red cell destruction, respectively.
Splenic needle biopsy/ splenoportography - clinical correlation
recalling the position of the spleen related to the diaphragm, any intervention utilizing a sharp instrument has the potential to enter the thoracic cavity at the costodiaphragmatic recess resulting in pleuritis (inflammation of the pleura)
Duodenum function
absorption of nutrients; site of openings of hepatopancreatic ducts for the addition of digestive enzymes and bile
duodenum definition
C-shaped loop of small intestine in continuity with the stomach proximally and jejunum distally
duodenum general remarks
named for its length- approximately 12 finger breadths (25 cm)
firmly affixed to the posterior abdominal wall (retroperitoneal location)
divided into 4 parts
Duodenum: First Part (Superior)
Direct continuity with pylorus
located approximately at the anterior and right lateral side of LV1
Completely peritonealized (surrounded by the hepatoduodenal ligament)
Relations-
anterior: gallbladder and quadrate lobe of the liver
Posterior: common bile duct, gastroduodenal artery and portal vein
Superior: neck of the gallbladder and cystic duct
Inferior: head of the pancreas
Duodenal bulb or cap
Due to the lack of internal mucosal folds, the first part of the duodenum is thin-walled. Because of this it is easily visualized through the use of radiopaque material and therefore radiologists refer to this area as the duodenal bulb or cap.
Note from lecture: because of the thin walls, this is a common site for ulcers to erode through.
Duodenum: Second part (Descending)
descends anterior to the right lateral border of LV1,2,3
Retroperitoneal
Receives the common bile duct and main pancreatic duct
Relations:
anterior- right lobe of the liver, gall bladder, transverse colon and its mesocolon, coils of small intestine
Posterior- hilum of the right kidney, right renal vessels, right ureter, right psoas major, IVC
Medial- head of the pancreas, gastroduodenal a., common bile duct and main pancreatic duct
Duodenum: third part (horizontal)
runs horizontally from right to left across LV3
retroperitoneal
Relations:
Anterior- superior mesenteric vessels and coils of the small intestine and the root of the mesentery
Posterior- psoas major, IVC, Aorta, right gonadal vessels and right ureter
Superior- head of the pancreas
Duodenum: fourth part (Ascending)
retroperitoneal (except for extreme terminal end)
ascends along the left side of the aorta to LV2
Turns abruptly, becomes peritonealized and joins the jejunum
Relations:
anterior- left side of the root of the mesentery and coils of small intestine
posterior- aorta, left gonadal vessels and left psoas
medial- head of the pancreas (uncinate process)
Suspensory muscle of the duodenum (Ligament of Treitz)
The duodenal-jejunal flexure is attached via a fibromuscular band, the suspensory muscle of the duodenum, to the posterior body wall in the area of the right crus of the diaphragm near the esophageal hiatus
Duodenum: internal anatomy
a. microscopic surface modifications, villi, provide increased surface are for absorption macroscopic circular folds of mucosa and submucosa (plica circularis) extend from the 2nd-4th part of the duodenum Greater and (possibly) lesser duodenal papilla
Greater duodenal papilla
Two papillae, nipple-like projections, may be raised on the mucosa of the posteromedial wall of the second part of the duodenum. The common bile duct and the major pancreatic duct join to form a dilated tube (hepato-pancreatic ampulla) prior to opening through the greater duodenal papilla. A lesser papilla may be seen proximal to the greater papilla if an accessory pancreatic duct is present.
Important anterior duodenal relations
gall bladder (1st and 2nd portion) transverse mesocolon (2nd portion) superior mesenteric vessels (3rd portion)
Important posterior duodenal relations
gastroduodenal artery (1st portion, second portion medially)
common bile duct (1st portion, 2nd portion medially)
hilum of right kidney (2nd portion)
right ureter (2nd & 3rd portions)
IVC (2nd and 3rd portion)
Aorta (4th portion)
Duodenal (peptic) ulcer
most occur in part I where stomach acid concentration is highest
erode posterior wall
can erode the gastroduodenal a. resulting in significant blood loss, peritonitis, formation of adhesions beetween organs located in the area, and pancreatitis.
Pancreas- function
Accessory gland of digestion:
- exocrine portion- elaborates digestive enzymes secreted directly into the gut
- endocrine portion- elaborates hormones important in sugar metabolism (insulin, glucagon) which are secreted into the blood
Pancreas, size and weight
approx. 85 grams, 20 cm.
Pancreas location
Except for tail, completely retroperitoneal (posterior to omental bursa)
Lies transversely across the posterior abdominal wall, from duodenum to spleen, posterior to the stomach (forms a significant portion of the stomach bed)
Pancreas regions
Head, Neck, Body and Tail
Pancreas: Head
area that lies within the concavity formed by the duodenum
Uncinate process
Relations: anterior- pylorus, transverse mesocolon, and coils of the small intestine
posterior- LV1-LV2, IVC and renal veins, aorta and right renal artery, and the bile duct which may be partially embedded within it
uncinate process
inferior hook-shapped process which lies in contact posteriorly with the aorta and is crossed anteriorly by the superior mesenteric vessels
Pancreas: Neck
continuous with the superior portion of the head
may appear somewhat constricted
Relations:
anterior- transverse mesocolon
posterior- grooved by the superior mesenteric vessels
portal vein, relation to pancreas
Posterior to the neck of the pancreas, the superior mesenteric vein receives the splenic vein thereby forming the portal vein
Pancreas: body
continuous with the neck
ascends slightly to the left
triangular in cross-section (apex directed anteriorly)
Relations:
anterior- stomach (through the omental bursa) and posterior body wall peritoneum
posterior- aorta, left suprarenal gland, left kidney and its vessels and the splenic vein which may course through the substance of the gland
Pancreas: tail
lies within the lienorenal ligament (only portion of the pancreas to be peritonealized)
contacts the hilum of the spleen
Important pancreatic relations: anterior
stomach & pylorus
SMA& V over uncinate process
Transverse mesocolon
Small intestine
Important pancreatic relations: posterior
Common bile duct IVC Portal vein Aorta Right renal a. & renal vv. Splenic a. & v. LV 1,2
Main Pancreatic Duct
Wirsung
extends from tail to head
joined by minor ducts in a “herring bone” pattern
lies toward the posterior surface of the gland and courses midway between the superior and inferior borders of the gland
In the head, curves inferiorward and courses more posteriorly within the gland
joins the common bile duct at the hepatopancreatic ampulla
opens into the distal one-third of the second portion of the duodenum via the greater duodenal papilla
accessory pancreatic duct
Santorini Often (15%) a highly variable accessory pancreatic duct (Santorini) drains a portion of the head of the pancreas. It usually opens proximal to the greater duodenal papilla on the posterior wall of the second part of the duodenum via the lesser duodenal papilla.
Pancreatitis
inflammation of pancreas due to:
- blocked hepatopancreatic ampulla/ main pancreatic duct causing reflux of bile and/or pancreatic digestive enzyme resulting in autolysis of pancreatic tissue
- causes: trapped gallstone in ampulla or main duct; trauma; alcoholism (binge drinking)
Pancreatic cancer (Head of pancreas)
largest cause of extra hepatic biliary obstruction
cancer compresses common bile duct and/or hepatopancreatic ampulla
results in obstructive jaundice; due to backing up of bile pigments, body’s tissues become stained yellow/ green
Pancreatic rupture
pancreas, located transversely across spine is susceptible to compression injuries (rapid deceleration and compression via steering wheel)
results in bleeding and autolysis of pancreatic and surrounding tissues due to dissemination of pancreatic enzymes throughout the abdomen
Liver- size
largest gland in the body; weighs approx. 2% of adult body weight (1.2-1.6 kg)
Liver: function
as a gland, the liver elaborates and secretes bile, important for digestion of fats
provides a storehouse for nutrients gained by digestion (via portal circulation) as well as an arena for anabolic synthesis
Carries out the process of deamination of amino acids
detoxifies agents harmful to the body (formation of urea utilizing ammonia)
Liver: location
Occupies most of the right upper quadrant directly below the dome of the right hemidiaphragm, protected by ribs 5-9
on the midline lies behind the xiphisternal junction
extends into the left upper quadrant to the fifth intercostal space below the apex of the heart
should not extend more than 1” inferior to the anterior rib margin
Liver: Surface anatomy: diaphragmatic surface
smooth due to conformity of the liver to the inferior surface of the diaphragm; diaphragmatic surfaces correspond to the following designations:
- Superior (right & left)
- Anterior (ventral) (Right & left)
- Right (lateral)
- Posterior (dorsal)
Liver: Surface anatomy: Visceral surface
Note: continuity of the visceral and diaphragmatic surfaces occurs anteriorly at the sharpened inferior border, while posterosuperiorly, this continuity is rounded.
a. directed inferiorly, and posteriorlyl
b. porta hepatis
c. sagittal fissure containing the ligamentum teres hepatis and the ligamentum venosum
d. two shallow fossae
Porta hepatis
located at the center of the visceral surface this area marks the entrance and exit of such structures as the hepatic arteries, portal vein, the hepatic bile ducts, nerves of the hepatic plexus and lymphatics of the liver. The porta is surrounded by the attachment of the lesser omentum.
Sagittal fissure
located immediately to the left of the porta hepatis is a sagittal fissure which contains inferiorly the ligamentum teres hepatis and superiorly the ligamentum venosum
Ligamentum teres hepatis
round ligament of the liver, derived from the umbilical vein
Liver: visceral surface: fossae
To the right of the porta two shallow fossae exit, also in the sagittal plane, parallel to the leftsagittal fissure. The inferior fossa contain the gall bladder; the superior fossa (caval fossa) contains the inferior vena cava (IVC).
“H” on the liver
The porta, together with the two sagittal landmarks create an “H” on the visceral surface of the liver. The “H” is the basis for division of the liver into four anatomical lobes.
Lobes of the liver
Right, Quadrate, Caudate, Left
Liver: right lobe
largest, approx 6x larger than the left lobe
Separated from the left lobe on the diaphragmatic surface by teh falciform ligament, and on the visceral surface by the left sagittal fissure
liver: right lobe fossae
- gall bladder fossa
- caval fossa
- portal fossa (porta hepatis)
Liver: right lobe impressions
- renal (right)
- colic (hepatic flexture)
- duodenal (1st & 2nd parts)
Liver: quadrate lobe
anatomical subdivision of the dorsal surface ofthe right lobe
situated between the inferior limbs and crossbar of the “H”
Liver: caudate lobe
anatomical subdivision of the dorsal surface of the right lobe
situated between the superior limbs and crossbar of the “H”
a “caudate process” separates the gall bladder fossa from the caval fossa
clinical note re: quadrate adn caudate lobe designations
Although the quadrate and caudate lobes are described as anatomic subdivisions of the right lobe, internal functional segments do not completely correlate with established external markings. By virtue of the distribution of hepatic arteries, portal veins and hepatic ducts (hepatic triad), they FUNCTIONALLY belong to the left lobe. These “vascularly defined” segments have greater import when considering surgical interventions, i.e. lobectomies.
Liver: left lobe (definition& impressions)
area directly to the left of the falciform ligament
Iimpressions: esophageal (may be present), gastric
Two sources of blood to the liver
Blood is brought to the liver: systemically and viscerally
Systemic circulation to the liver
Right and left hepatic arteries branch from the proper hepatic artery within the porta. Each hepatic artery courses parallel to the bile duct network which drains functional right and left lobes
Visceral circulation to the liver
- Blood from the organs of digestion and their accessory glands reaches the liver via the portal vein.
- Branches of hepatic arteries and portal veins BOTH feed into hepatic sinusoids
- Hepatic sinusoids are drained by CNETRAL VEINS which coalesce to form tributaries which will eventually form HEPATIC VEINS.
- Three hepatic veins drain the liver to the IVC within the caval fossa.
Hepatomegaly
increase in the overall size of the liver due to:
a. congestive heart failure resulting in backing-up of blood due to increased resistance to blood flow through the lungs
b. hepatitis (inflammation due to various causes)
c. metastatic carcinoma
Increases in the amount of blood housed in the liver…
at any one time is the result of the lack of valves within the hepatic veins and IVC. Increase in central venous pressure causes the liver to become engorged with blood. Pooling of blood within the liver can be deomonstrated by pushing on the right upper quadrant resulting in distension of neck veins.
Cirrhosis
a. progressive hepatocellular change in the form of increased fibrosis and fat deposition due to the continued exposure to toxic substances, i.e. industrial solvents, alcohol (highest frequency).
b. results in “hobnail” appearance of liver surface and portal hypertension.
