16-01-23 - Oesophagus, Stomach & Duodenum Flashcards
Learning outcomes
- Describe the anatomy (position, function, relations, neurovascular supply) of the oesophagus
- Describe the anatomy (position, function, relations, neurovascular supply) of the stomach
- Describe the anatomy (position, function, relations, neurovascular supply) of the duodenum
- Discuss the clinical implications of the anatomy of the lower end of the oesophagus, the stomach and the duodenum
- Identify anatomical structures on medical images
What are the embryonic gut divisions?
What does each section contain?
How is blood supply, lymphatics, and innervation linked between these divisions?
- The abdominal organs are divided into 3 parts based on embryological origin:
1) Foregut
* Oesophagus to mid-duodenum
* Liver + gall bladder
* ½ of pancreas
2) Midgut
* Mid-duodenum to proximal 2/3rds of Transverse colon
* ½ of pancreas
3) Hindgut
* Distal 1/3rd of Transverse colon to Proximal ½ of Anal canal
* Arteries and veins of each area have similar names
* Lymphatics from each share a similar path
* Nerves from each area follow a common path
What is the arterial supply of the stomach?
What are the 3 divisions of the coeliac trunk?
- The arterial supply of the stomach is the coeliac trunk
- 3 divisions of the coeliac trunk:
1) Common hepatic artery
2) Left gastric artery
3) Splenic artery
What is the role of the oesophagus?
Where does the oesophagus start?
Where does it descend between?
Where does it enter the thorax?
Where does it enter the abdominal cavity?
- The role of the oesophagus is the transport of food and fluid to stomach by peristaltic waves
- The oesophagus starts in the midline as the continuation of the pharynx at C6, inferior border of cricoid cartilage
- It descends between the trachea and the vertebral column
- The oesophagus enters the thorax behind trachea, with the arch of the aorta to its left in the superior mediastinum
- It then enters the abdominal cavity at T10, slightly left of the midline
What are the 4 non-pathological constrictions of the oesophagus?
What level is each constriction at?
What is the significance of the
Cricopharyngeal sphincter?
What are 3 reasons why constrictions can cause problems?
- 4 non-pathological constrictions of the oesophagus:
1) Upper oesophageal [cricopharyngeal] sphincter – Level of T6
2) Arch of aorta – Level of T4
3) Left main bronchus
4) Diaphragm – Level of T10
- The Cricopharyngeal sphincter between the pharynx and the oesophagus prevents air entering the stomach via oesophagus
- 3 reasons why constrictions can cause problems. Constrictions are more likely to:
1) Are more likely to cause blockage
2) Hinder passage of instruments
3) Slow down the passage of caustic substances → more damage
Superior, middle, and inferior 1/3rd of the oesophagus:
* Muscle type
* Swallowing
* Arterial supply
* Venous drainage
* Innervation
* Lymphatic drainage
How large is the abdominal oesophagus?
Where does the abdominal oesophagus extend between?
Where does it enter into the abdominal cavity?
What is the abdominal oesophagus tethered by?
- The abdominal oesophagus is the shortest part
- It extends from the oesophageal hiatus to the cardiac orifice of the stomach
- It passes through the right crus of the diaphragm at T10 to enter the abdominal cavity
- The abdominal oesophagus is tethered to the margins of the oesophageal hiatus by the phreno-oesophageal ligament
What is the arterial supply of the abdominal oesophagus?
What 2 places does the venous drainage of the abdominal oesophagus go to?
What is the nerve supply to the abdominal oesophagus?
Where can pain from the lower oesophagus be referred to?
What is the lymph drainage of the oesophagus?
- Arterial supply of the abdominal oesophagus is from the branches of left gastric artery, a branch of coeliac trunk
- Veins of the abdominal oesophagus drain to the portal vein (left gastric, short gastric veins) and azygos system (oesophageal veins).
- Nerve supply is by the oesophageal plexus
- Parasympathetics from Vagus
- Sympathetics from greater splanchnic nerve
- Pain from the lower oesophagus is referred to the retrosternal area
- The lymph drainage of the oesophagus are the left gastric lymph nodes, which then drain into the celiac lymph nodes
What can be triggered due to cirrhotic liver disease?
- Cirrhotic liver disease can lead to the liver tissue being inflexible and tough, which compresses the hepatic portal vein, leading to portal hypertension
- Instead of blood from going the hepatic portal vein to the IVC to the heart, it travels to the thoracic cavity and is drained by other veins (e.g azygos)
- These veins can’t handle much blood and will swell, leading to blood backing into oesophageal veins and forming oesophageal varices (expanded blood vessels in the oesophagus)
Where is there a high-pressure zone (HPZ) around the oesophagus?
What are 2 major anti-reflux mechanisms of the oesophagus?
What are 2 minor anti-reflux mechanisms of the oesophagus?
What is the oesophageal sphincter made up of?
What is achalasia?
What can cause achalasia?
- There is a high-pressure zone (HPZ) around the lower 2-4 cm of oesophagus
- 2 major anti-reflux mechanisms of the oesophagus:
1) Circular smooth muscle fibers in the lower oesophagus
2) The right crus of the diaphragm
- 2 minor anti-reflux mechanisms of the oesophagus:
1) Clasp fibres
2) Oblique entry of the oesophagus into the stomach
- Anatomical and physiological features are collectively referred to as the lower oesophageal sphincter
- Achalasia is a rare disorder of the food pipe (oesophagus), which can make it difficult to swallow food and drink
- Achalasia can be caused by ganglion cells in the myenteric plexus of the distal oesophagus and gastro-oesophageal junction being reduced or absent
What structures extend up the abdominal oesophagus?
How is the gastro-oesophageal function identified?
What is Barrett’s oesophagus?
What is a Mallory-Weiss tear?
How is it often caused?
- Gastric fundal mucosal folds extend a variable distance up the abdominal oesophagus.
- The gastro-oesophageal junction is usually identified by a circumferential ‘zigzag’ line (‘Z line’) between the pale pink oesophageal squamous epithelium above and the red columnar epithelium below
- Barrett’s Oesophagus is the pathological replacement of oesophageal squamous epithelium by gastric columnar epithelium
- A Mallory-Weiss tear is a tear of the tissue of your lower oesophagus.
- It is most often caused by violent coughing or vomiting
What is the stomach?
Where is it located?
What is the Labbe triangle?
What 3 structures make up Labbe triangle?
- The stomach is a muscular sac
- The stomach is located in epigastric, left hypogastric (hypochondrial) and, partially, umbilical regions
- Labbe triangle is the location where the stomach is normally in contact with the abdominal wall
- 3 structures make up Labbe triangle:
1) Left costal arch
2) Lower border of the liver
3) Horizontal line connecting the tips of right and left 9th costal cartilages
What are 7 functions of the stomach?
- 7 functions of the stomach:
1) Temporary storage of ingested food
2) Mechanical breakdown of solid food
3) Chemical digestion of proteins
4) Mixes the food with gastric secretions to form chyme
5) Regulation of the rate of passage of the chyme to the duodenum
1) Secretion of:
* Mucus
* Acid to aid digestion and absorption of iron
* Intrinsic factor for vitamin B12 absorption
* Gut hormones
2) Microbial defence
What is the gastric mucosa of the stomach lined with?
What is the purpose of this?
What are 3 different cell types in the stomach?
What do they each produce?
- The gastric mucosa of the stomach is lined by a simple columnar epithelium (surface lining cells) which secrete a thick coating of alkaline mucous
- This protects the gastric mucosa from the effects of acid and enzymes (autodigestion)
- 3 different cell types in the stomach:
1) Parietal (oxyntic) cells
* Make hydrochloric acid, and intrinsic factor
* Intrinsic factor is needed for absorption of vitamin B12 in the terminal ileum
2) Chief (Peptic, zymogenic) cells
* Produce precursors of pepsin (as well as lipase)
* Pepsin down proteins into smaller peptides
3) DNES (formerly APUD) cells
* Produce hormones such as gastrin (by G cells in the pyloric antrum) and somatostatin (by delta cells in pyloric antrum)
What 5 structures is the stomach related to anteriorly?
What 8 structures is the stomach related to posteriorly?
- 5 structures the stomach is related to anteriorly:
1) Anterior abdominal wall
2) Left costal margin
3) Diaphragm
4) Left pleura & lung (via diaphragm)
5) Left lobe of the liver - 8 structures the stomach is related to posteriorly:
1) Lesser sac
2) Spleen
3) Upper pole of left kidney
4) Left suprarenal gland
5) Pancreas
6) Splenic artery
7) Transverse colon
8) Transverse mesocolon