Organs of the Gastrointestinal Tract Lecture (Test 1) Flashcards
(41 cards)
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