Oesophagus

Question 1

At what vertebral level is the oesophageal hiatus?

Answer 1

T10

Question 2

What layers of muscle make up the oesophagus?

Answer 2

Internal circular layer

External longitudinal layer

Question 3

What three muscle types make up the external longitudinal layer?

Answer 3

Superior third = voluntary striated
Middle third = voluntary mixed (smooth and striated)
Inferior third = smooth muscle

Question 4

What is the upper oesophageal sphincter?

Answer 4

Anatomical, striated muscle sphincter located between the pharynx and the oesophagus.
Normally closed to prevent air entering the oesophagus.

Question 5

What is the lower oesophageal sphincter?

Answer 5

Physiological sphincter located in the gastro-oesophageal junction (T11)

Question 6

What are the four features of the LOS that allow it to do its job?

Answer 6

1. Acute angle at which oesophagus enters stomach
2. Positive intra-abdominal pressure causes compression of oesophagus
3. Mucosa folds help to occlude lumen
4. Right crus of diaphragm has clamping effect

Question 7

What is the blood supply to the oesophagus?

Answer 7

Thoracic part - thoracic aorta and inferior thyroid artery

Abdominal part - left gastric artery (branch of coeliac trunk) and left inferior phrenic artery

Question 8

What is the venous drainage of the thoracic part of the oesophagus?

Answer 8

Branches of the azygous vein and inferior thyroid vein

Question 9

What is the venous drainage of the abdominal part of the oesophagus?

Answer 9

Mixed drainage via two routes:

1) to portal circulation via left gastric vein
2) to systemic circulation via azygous vein

Question 10

What is the nerve innervation to the oesophagus?

Answer 10

Oesophageal plexus (combination of parasympathetic input from vagal trunks and sympathetic fibres from the cervical and thoracic sympathetic trunks)

Question 11

What is the lymph drainage of the oesophagus?

Answer 11

Superior third = deep cervical lymph nodes
Middle third = superior and posterior mediastinal nodes
Inferior third = left gastric and coeliac nodes

Question 12

How does Barrett’s oesophagus occur?

Answer 12

Chronic acid exposure as a result of a malfunctioning LOS

Acid irritation causes metaplasia of lower oesophageal squamous epithelium to gastric columnar epithelium

Question 13

What is the cause of Oesophageal varices?

Answer 13

Abnormally dilated submucosal veins within anastomosis of systemic and portal circulation usually caused by portal hypertension (as a result of chronic liver disease)

Question 14

What type of epithelium lines the oesophagus?

Answer 14

Stratified squamous mucosa epithelium [interdigitates with the glandular epithelium of the stomach at the gastroesophageal junction]

Mucous glands present in the submucosa layer to provide lubrication