5. Abdomen 5- Oesophagus, stomach, duodenum.pptx Flashcards
Change of muscle in the oesophagus?
Upper 1/3: striated muscle as swallowing is voluntary and rapid
Lower 1/3: smooth muscle, involuntary
Middle 1/3: mixed
Cricopharyngeal sphincter:
What is it?
Function?
Indentation caused by the normal function of the cricopharyngeal sphincter between the pharynx and the oesophagus
Function:It is to prevent air being sucked into the stomach during inhalation
Superior/cervical third of oesophagus: Begins at? Arterial supply? Venous drainage? Nerve supply? Lymphatics?
Begins at C6
Arterial supply from inferior thyroid arteries
Venous drainage to brachiocephalic veins
Nerve supply from branches of the vagus nerves (recurrent laryngeal nerves)
Lymphatics drain to deep cervical nodes
Middle/thoracic third of oesophagus: Arterial supply? Venous drainage? Nerve supply? Lymphatics?
Arterial supply direct from thoracic aorta and bronchial arteries
Venous drainage to azygos system (systemic)
Nerve supply from the oesophageal plexus (vagus and sympathetic)
Lymphatics drain to tracheobronchial nodes
Inferior/ abdominal third of oesophagus: Arterial supply? Venous drainage? Nerve supply? Lymphatics?
Arterial supply from left gastric artery
Venous drainage to left gastric veins and therefore to portal vein
Nerve supply from branches of the oesophageal plexus (vagus and sympathetic)
Lymphatics drain to left gastric and coeliac nodes
What are the 4 oesophageal constrictions?
- Upper oesophageal sphincter 17cm
- Arch of aorta
- Left main bronchus at 28cm
- Diaphragm (lower oesophageal sphincter) at 43cm
Structures anterior to the oesophagus (5)
Trachea Right pulmonary artery Left main bronchus Left atrium Diaphragm
Structures posterior to the oesophagus (3)
Vertebral bodies (C6 – T12) Thoracic duct (partly) Thoracic aorta (inferiorly)
Name a structure on the RHS and LHS of the oesophagus?
Thoracic aorta lies to the left
Azygos vein lies to the right
What is the epithelium and muscle type of the oesophagus?
It is lined by stratified squamous epithelium (transport) with submucosal mucous glands (lubrication) and has smooth muscle walls
Abdominal oesophagus: Where does it enter the abdomen? Arterial supply? Venous drainage? Lymph drainage? Nervous supply?
Where does it enter the abdomen?
It passes through the right crus of diaphragm at T10 (or 7th costal cartilage), but just to the left of the midline
Arterial supply?
Arterial supply is from the left gastric artery (and inferior phrenic)
Venous drainage?
Is to the portal vein
Lymph drainage?
Is to nodes along the left gastric artery and then coeliac nodes
Nervous supply?
By the oesophageal plexus, which is both vagal (p’symp and afferent) and sympathetic
What is the cardiac orifice?
The superior opening into the stomach from oesophagus
What forms the porto-systemic or portocaval anastomosis
Submucosal veins in the oesophagus form an anastomosis between its middle and lower thirds. The middle third drains to the azygos vein that drains to the SVC (systemic). The lower third drains to the left gastric vein that drains to the portal vein. Therefore this anastomosis is between the portal and systemic circulations i.e. a porto-systemic or portocaval anastomosis
Consequence of cirrhotic liver disease
Cirrhotic liver disease raises the portal venous pressure (portal hypertension) and blood escapes via the submucosal veins in the oesophagus and in to the systemic azygos vein. Consequently the veins become dilated and tortuous: oesophageal varices
–> Which may cause fatal haemorrhage
How is reflux prevented at the lower end of the oesophagus? 3
No anatomical sphincter, physiological sphincter
Reflux is prevented by a “physiological” cardiac sphincter: 1. Contraction of the right crus of the diaphragm
- The tonic contraction of the circular layer of smooth muscle in the lower oesophagus
- The “valvular” effect of the oblique entry of the oesophagus into the stomach, augmented by the oblique muscle layer
Sphincter closure under vagal control
What does z-line is oesophagus show?
The transition from stratified squamous (oesophageal) to columnar (gastric) epithelium is visible as the Z-line