Organs of the Gastrointestinal Tract Lecture (Test 1) Flashcards
Esophagus
A) The Thoracic Esophagus pierces the Diaphragm at T10
- This is the Esophageal Hiatus and is slightly LEFT to the Midline
B) Then the Abdominal Esophagus turns sharply to the left to enter the Stomach at the CARDIAC ORIFICE at about T11
- The Abdominal Esophagus is about 2.5 cm long
- The Esophageal Sphincter is Physiologic, not well defined Anatomically
Structures pass through the Diaphragm at T8, T10, and T12
IVC = T8
Esophageal Hiatus = T10
Aorta = T12
**Openings in the Diaphragm are called “Hiatus”
“I 8, 10 Eggs, At 12”
“Sliding” Hiatal Hernia
- Esophageal Hiatus of Diaphragm enlarges or Weakens
- ABDOMINAL ESOPHAGUS and parts of the Stomach (Cardia and sometimes Fundus) herniate into the Thorax
Paraesophageal Hiatal Hernia
- A defect in Diaphragm next to the Esophageal Hiatus
- Permits FUNDUS of Stomach to Herniate (not usually the Esophagus)
Stomach
- Location: Left Hypochondria and Epigastric Regions
- Left End fixed at T10-11
- Right end fixed at L1-2
- The area between is VARIABLE
Stomach: Parts, Surfaces, and Curves
Parts:
- Fundus
- Cardiac Part, Cardiac Orifice
- Body
- Pylorus
- Pyloric Antrum (Entrance to Pylorus)
Surfaces:
- Rugae
- Pylorus (Pyloric Sphincter)
- Pyloric Orifice (Entrance to the Duodenum)
Curvatures:
- Lesser
- Greater
Stomach: Relationships
POSTERIOR to the Stomach:
- Diaphragm
- Spleen (Posterior and Lateral)
- Left Suprarenal Gland
- Upper Left Kidney
- Pancreas
- Left Colic Flexure
- Left Transverse Colon
- Transverse Mesocolon
ANTERIOR to the Stomach:
- Anterior Abdominal Wall
- Left Costal Margin
- Left Diaphragm
- Left and Quadrate Lobes of the Liver
Small Intestine
- The Small Intestine is located between the stomach and the large Intestine
3 Parts:
1) Duodenum
2) Jejunum
3) Ileum
Duodenum
GENERAL
General
- C Shaped
- 10 Inches long (12 finger-breadths)
- Located approximately at L1 to L4 Vertebral Bodies
- Starts at the Pylorus of the Stomach and ends at the Duodenal-Jejunal junction
Further divided into 4 parts:
1) Superior
2) Descending
3) Horizontal
4) Ascending
Duodenum Cont
A) Secondarily Peritoneal
- Except for some of the 1st and 4th parts
B) Covered Anteriorly by Peritoneum except where the Mesocolon of the Transverse Colon crosses and 2nd part
C) The 1st part is surrounded by the Hepatoduodenal Ligament
D) The root of the Mesentery begins at the Duodenal Jejunal Flexure
Duodenum
FEATURES of the 1st PART
Features of the 1st Part (Superior):
- Starts at the Pyloric Sphincter
- About 2 inches long
- Held in place by the Hepatoduodenal Ligament
- Portal Vein, Hepatic Artery and Bile Duct are therefore Posterior and Superior to this part
- Duodenal Bulb (Widened area)
- The head of the Pancreas is Inferior to this part
Duodenum
FEATURES of the 2nd PART
Features of the 2nd Part (Descending):
- About 3 inches long
- ALL RETROPERITONEAL (Secondarily)
- The Fundus of the Gall Bladder, Right Lobe of the Liver, Transverse Colon are all ANTERIOR
- The Right Kidney and Ureter are Posterior
- The Head of the Pancreas is MEDIAL
- The Bile and Pancreatic ducts enter into the Second Part of the Duodenum at the Major Duodenal Papilla
Duodenum
FEATURES of the 3rd PART
Features of the 3rd Part (Horizontal):
- The SUPERIOR MESENTERIC Artery and Vein and the root of the Mesentery Cross the Anterior Surface of the 3rd part of the Duodenum
- The Head o the PANCREAS is Superior
- The JEJUNUM is Anterior and Inferior
Duodenum
FEATURES of the 4th part
Features of the 4th Part (Ascending):
- Becomes INTRAPERITONEAL (is not covered by Parietal Peritoneum)
- The Root of the Mesentery and Jejunum are Anterior
- The Left Margin of the Aorta and Medial border of the Psoas Muscle are Posterior
- The 4th part is held in place by the SUSPENSORY LIGAMENT (or muscle) of the Duodenum (of Treitz)
- The SUSPENSORY LIGAMENT anchors the 4th part of the Duodenum to the RIGHT CRUS of the Diaphragm
Jejunum and Ileum
GENERAL
General
- Occupy most of the Peritoneal Cavity of Abdomen and Pelvis
- Coiled and about 20 feet long
- The Jejunum begins at Duodenal-Jejunal Junction and the Ileum ends at the Ileo-cecal Valve
- This part of the Small Intestine is VERY MOBILE and is held to Posterior Wall by the MESENTERY
- Jejunum and Ileum are “Framed” by the Large Intestine
- They are often called the “Free” Small Intestine
Jejunum
- 8 to 10 feet long
- 2/5 of the Free Small Intestine
- Simple Vascular Arcades, Long Vasa Recta, more Vascular
- Greater Diameter, Thicker, More PLICAE CIRCULARS (Circular Folds)
Ileum
- 10 to 12 feet long
- 3/5 of the free small Intestine
- Has compound Vascular Arcades, Shorter Vasa Recta, is Less Vascular
- Is Smaller Diameter, Thinner Wall
- Fewer PLICAE CIRCULARIS (Circular Folds)
Ileum
MECKEL’S (ILEAL) DIVERTICULUM
Michael’s (Ileal) Diverticulum can be a feature of the Ileum
- The most common Congenital Anomaly of the Small Intestine
- Arises from the ANTIMESENTERIC BORDER of the Ileum
- Occurs in about 2% of the population
- About 2 feet from the ILEOCECAL JUNCTION
- Average about 2 inches long
- Remnant of the VITELLINE DUCT
- Clinically difficult to distinguish from appendicitis
- May contain other types of tissue
Jejunum and Ileum
THE MESENTERY
Mesentery:
- 15 cm long at the root
- Attaches the Jejunum and Ileum to the Posterior Body Wall
Mesentery Crosses:
- LV1-2
- 3rd part of Duodenum
- Aorta
- IVC
- Right Ureter
- Right Gonadal Vessels
- Right Psoas Major
- Ends ar Right S.I. Joint
Jejunum and Ileum
THE MESENTERY LAYERS
The Mesentery:
- Is made up of 2 layers of PERITONEUM with Nerves, Lymph Nodes and Vessels, Fat, Arteries and Veins running between them
- Is 6 to 7 inches long at it’s root and 20 feet long at it’s Intestinal border
Large Intestine
REGIONS
Regions:
- Cecum and Vermiform Appendix
- Ascending Colon
- Right Colic Flexure
- Transverse Colon
- Left Colic Flexure
- Descedngin Colon
- Sigmoid COlon
- Rectum and Anal Canal are in the Pelvis
Large Intestine
GENERAL CHARACTERISTICS
General Characteristics
- The Large Intestine is HIGHLY MOBILE and location of its parts is VARIABLE
- FUNCTIONS: Fecal formation, Transport and Evacuation, Water Absorption and Mucus Secretion
- TAENIA COLI are 3 bands of Longitudinal Muscle on the OUTSIDE of the COLON
a) They converge at the root of the Appendix
b) They produce HAUSTRAE (Sacculations) that slow the movement of feces
- APPENDICES EPIPLOICAE (epiploic Appendages)
a) TAGS of FAT
b) Characteristic of the Large Intestine
Cecum
- No Epiploic Appendages
- Blind “pouch” Inferior to Ileocecal Orifice
- ILIOCOLIC VALVE is 2 folds that are not a True Sphincter
- ILEAL PAPILLA is a cone-like projection of the Ileum into the Cecum
- The Opening for the APPENDIX is Inferior to the ILEAL PAPILLA
Vermiform Appendix
- Usually attached to the POSTEROMEDIAL part of the Cecum
- Located at the Junction of 3 TAENIA COLI
- 9 to 10 cm long and supported by MESOAPPENDIX (not a true Mesentery)
- POSITION VARIABLE
Parts of Colon
1) ASCENDING COLON
- Right Colic Flexure (Hepatic Flexure)
- SECONDARILY RETORPERITONEAL (Usually)
- Except the Lowest part
2) TRANSVERSE COLON
- Left Colic Flexure (Splenic Flexure)
- INTRAPERITONEAL (Transverse Mesocolon)
3) DESCENDING COLON
- SECONDARILY RETROPERITONEAL
4) SIGMOID COLON
- INTERPERITONEAL (Sigmoid Mesocolon)
Rectum
- The Rectum is between SIGMOID COLON and ANAL CANAL
- ANORECTAL LINE
a) A line joining the tops of Anal Columns - Transverse Rectal Folds
a) Superior
b) Intermediate
c) Inferior - RECTAL AMPULLA
a) Dilated terminal part of Rectum
b) The Rectum is Superior to Anorectal Junction (Line)- A line joining the tops of the Anal Columns*
PUBORECTALIS MUSCLE:
- Relaxation = Defecation
Anal Canal
1) ANORECTAL LINE
- A line joining the tops (Superior ends) of the Rectal Columns
a) Anal Valves (At the base of the Anal Columns)
b) Anal Sinuses (Spaces between and at the Inferior part of the Anal Columns)
2) PECTINATE LINE
- A line joining the Inferior ends of the Anal Valves (DENTATE LINE)
Spleen
SIZE, SHAPE, LOCATION
- Left Hypochondriac Region
- Parallels Left Ribs 9, 10, and 11
- Midaxillary Line, between Stomach and Diaphragm
- About the size of a Hand
- Normally not Palpable below the Costal Margin
Spleen
RELATIONSHIPS
Peritoneal Relationships:
- Covered by Peritoneum
- Develops in the Dorsal Mesentery from MESODERM
a) GASTROSPLENIC Ligament
b) SPLENORENAL Ligament
Relations:
- The Diaphragm is Posterior
- The Stomach, Left Colic Flexure and tail of the Pancreas are ANTERIOR to the Spleen
Spleen
SURFACES
- The Left Kidney and Phrenicolic Ligament are Inferior to the Spleen
- DIAPHRAGMATIC SURFACE
a) Against Diaphragm
b) Smooth - VISCERAL SURFACE
a) Hilum with Gastrosplenic and Splenorenal Ligaments
b) There are Colic, Gastric and Renal Impressions on the Visceral Surface of the Spleen
Pancreas
GENERAL
- The Pancreas i (mostly) RETROPERITONEAL (Sedentarily)
- Located at about L1-L2
Parts:
1) Head
- With Uncinate process in the Duodenal Curve
2) Body:
- Triangular Cross-section
3) Neck:
- Constricted part between head body
4) Tail:
- Some of the Tail is located in the Splenorenal Ligament
- Anterior t the Hilus of the Spleen
Pancreas
RELATIONSHIPS
- Superior Mesenteric Artery and Vein ad Posterior to the Neck
- Splenic Vein and Artery run horizontally Superior to or Posterior to Body
- The tail is against the Spleen
- Inferior Vena Cava and the Aorta are Posterior to the Body
- The Stomach is Anterior to the Spleen
- The Duodenum is Superior, right and Inferior to the Head
- The Transverse Colon lies Anterior and Inferior to the Pancreas
Pancreatic Duct System
- The Pancreas develops from a Ventral Bud in the Ventral Mesentery and a large Dorsal Bud in the Dorsal Mesentery
- Rotation of the Stomach and Duodenum brings these buds together and the duct systems unite
- The main or major Pancreatic Duct joins the Bile Duct and they enter the 2nd part of the Duodenum together through a common HEPATOPANCREATIC AMPULLA —-> This forms the Major Duodenal Papilla
- The AccessoryPancreatic Duct (of Present) enters the Duodenum at the more Superior MINOR DUODENAL PAPILLA
The Liver
- Most of the Liver is located in the RIGHT UPPER QUADRANT
- The Smaller Left Lobe is located in the Left Upper Quadrant
Lobes:
- Left Lobe
- Right Lobe
- Caudate Lobe
- Quadrate Lobe
**FALCIFORM Ligament is a double layer of Peritoneum that connects Liver to the Anterior Wall
Liver Surfaces and Ligaments
1) DIAPHRAGMATIC SURFACE:
- Smooth, fits Concavity of Diaphragm
- Peritoneum attaches the Liver is to the Anterior Body Wall and the Peritoneum splits to enclose a “bare Area” of the liver
- This Bare area is defined by Anterior, Posterior, Left, and Right Coronary Ligaments
- The Bare Area includes the area where the IVC is Posterior to the Liver and the Hepatic Veins drain into it
2) VISCERAL SURFACE:
- Ligamentum Venosum
- Round Ligament
- Hepatic Fossa for Gall Bladder
Visceral Surface Features
1) The Porta Hepatic
- A Transverse Fissure between Caudate and Quadrate Lobes that transmits the Portal Triad:
a) Hepatic Artery (Proper)
b) Portal Vein
c) Bile Duct
2) Ligamentum Teres
- In the edge of the Falciform
- Obliterated Umbilical Vein
3) Ligamentum Venosum
- The “Old” Ductus Venous
- Used to connect the Umbilical Vein with the Inferior Vena Cava
4) Hepatic Fossa for Gall Bladder
Functional Lobes vs Anatomical Lobes of Liver
Anatomical Lobes:
- Left
- Right
- Quadrate
- Caudate
Functional Lobes:
- Right
- Left
Peritoneal Attachment on Liver
- FALCIFORM Ligament with Ligamentum Teres
- LESSER MOMENTUM with HEPATODUODENAL and HEPTAOGASTRIC Ligaments
Gall Bladder and Biliary Tract
GENERAL
General
- Lies in Hepatic Fossa
- Fundus:
a) The Lowest, widest part
b) Contracts Anterior abdominal wall at the Midclavicular line, 9th or 10th Costal Cartilage
c) Usually located on the TRANSPYLORIC Line
Gall Bladder and Biliary Tract
Parts and Extrahepatic Bile Passages
Parts:
- Fundus
- Body
- Neck
Extra hepatic Bile Passages:
- Right Hepatic Duct (R) and Left Hepatic Duct (L) together form the COMMON HEPATIC DUCT
- The CYSTIC DUCT then adds to the COMMON HEPATIC DUCT to form the COMMON BILE DUCT
Bile Duct
- Formed from the Cystic and Common Hepatic Ducts
- Runs in the edge of the Lesser Momentum (Hepatoduodenal Ligament)
- Goes POSTERIOR and INFERIOR to the 1st part of the Duodenum, Posterior to the Head of the Pancreas, enters the 2nd part of the Duodenum with the Pancreatic Duct at the MAJOR DUODENAL PAPILLA
