The Oesophagus - Anatomy Flashcards
Where does the oesophagus begin?
In the neck at the level of C6
What is the oesophagus continuous with superiorly?
The laryngopharynx
Does the oesophagus sit in front of or behind the trachea?
Behind the trachea
Where does the oesophagus enter the abdomen?
Via the oesophageal hiatus at T10
Where does the oesophagus terminate?
By joining the cardiac orifice of the stomach at T11
What are the 4 layers of the oesophagus?
- Adventitia
- Muscle layer
- Submucosa
- Mucosa
What is the adventitia?
Outer layer of connective tissue (the very distal and intraperitoneal portion of the oesophagus has an outer covering of serosa, instead of adventitia)
Describe the muscle layer?
External layer of longitudinal muscle and inner layer of circular muscle
Describe the mucosa?
Non-keratinised stratified squamous epithelium (continuous with columnar epithelium of the stomach).
How is food transported through the oesophagus?
By peristalsis
What is dysphagia?
Difficulty swallowing
What are the 2 sphincters present in the oesophagus?
Upper and lower oesophageal sphincters
Describe the upper oesophageal sphincter?
An anatomical, striated muscle sphincter at the junction between the pharynx and oesophagus. It is produced by the cricopharyngeus muscle.
Function of the upper oesophageal sphincter?
Normally, it is constricted to prevent the entrance of air into the oesophagus
Describe the lower oesophageal sphincter?
A physiological sphincter located in the gastro-oesophageal junction (junction between the stomach and oesophagus). The gastro-oesophageal junction is situated to the left of the T11 vertebra
What is the lower oesophageal sphincter marked by?
arked by the change from oesophageal to gastric mucosa.
Why is the lower oesophageal sphincter physiological?
It does not have any specific sphincteric muscle
What is the function of the lower oesophageal sphincter?
During oesophageal peristalsis, the sphincter is relaxed to allow food to enter the stomach. Otherwise at rest, the function is to prevent the reflux of acidic gastric contents into the oesophagus.
What are the physiological constrictions of the oesophagus? What is likely to happen here?
Where food/foreign objects are most likely to become stuck
A - Arch of aorta
B - Bronchus (left main stem)
C - Cricoid cartilage
D - Diaphragmatic hiatus
Where does the thoracic part of the oesophagus receive its arterial supply from?
The branches of the thoracic aorta and the inferior thyroid artery (a branch of the thyrocervical trunk)
What does venous drainage of the thoracic part of the oesophagus occur via?
Branches of the azygous veins and the inferior thyroid vein
What is the abdominal oesophagus supplied by?
The left gastric artery (a branch of the coeliac trunk) and left inferior phrenic artery
What is the abdominal oesophagus drained by?
2 routes:
- To the portal circulation via left gastric vein
- To the systemic circulation via the azygous vein
These two routes form a porto-systemic anastomosis, a connection between the portal and systemic venous systems.
What is the oesophagus innervated by?
The oesophageal plexus
What is the oesophageal plexus formed by?
A combination of the parasympathetic vagal trunks and sympathetic fibres from the cervical and thoracic sympathetic trunks.
What is Barrett’s oesophagus?
Metaplasia (reversible change from one differentiated cell type to another) of lower oesophageal squamous epithelium to gastric columnar epithelium
What is Barrett’s oesophagus usually caused by?
It is usually caused by chronic acid exposure as a result of a malfunctioning lower oesophageal sphincter. The acid irritates the oesophageal epithelium, leading to a metaplastic change.
What is the most common symptom of Barrett’s oesophagus?
A long-term burning sensation of indigestion.
What are the clinical features of oesophageal carcinomas?
- Dysphagia
2. Weight loss
What are the 2 major types of oesophageal carcinomas?
- Squamous cell carcinoma
2. Adenocarcinoma
Where can squamous cell carcinoma occur?
The most common subtype of oesophagus cancer. It can occur at any level of the oesophagus.
Where can adenocarcinoma occur?
Only occurs in the inferior third of the oesophagus and is associated with Barrett’s oesophagus. It usually originates in the metaplastic epithelium of Barrett’s oesophagus.
What are oesophageal varices?
Abnormally dilated submucosal veins that lie within the anastomosis (between portal and systemic circulation)
What are oesophageal varices predisposed to?
Predisposed to bleeding, with most patients presenting with haematemesis (vomiting of blood). Alcoholics are at a high risk of developing oesophageal varices.
