Oesophagus Flashcards
Describe the oesophagus
The oesophagus is a fibromuscular tube, approximately 25cm in length, that transports food from the pharynx to the stomach.
Describe the course of the oesophagus
The oesophagus begins in the neck, at the level of C6. Here, it is continuous superiorly with the laryngeal part of the pharynx (the laryngopharynx).
It descends downward into the superior mediastinum of the thorax, positioned between the trachea and the vertebral bodies of T1 to T4. It then enters the abdomen via the oesophageal hiatus (an opening in the right crus of the diaphragm) at T10.
It terminates by joining the cardiac orifice of the stomach at level of T11.
How long is the oesophagus
25cm
Describe the structure of the oesophagus
It is made up of 4 layers and they include:
Adventitia- Outer layer of connective tissue.
Muscular layer-external layer of longitudinal muscle and inner layer of circular muscle.
Submucosa-
Mucosa- non-keratinised stratified squamous epithelium.
Food is transported through the oesophagus by
Peristalsis.
How many sphincters does the oesophagus have
2- Upper and lower oesophageal sphincters.
Upper oesophageal sphincter is located where
Junction between pharynx and oesophagus.
Produced by cricopharyngeus.
Lower oesophageal sphincter is located where
Gastro-esophageal junction-between stomach and esophagus.
It is a physiological sphincter.
Function of cricopharyngeus
It constricts to prevent the entrance of air into the oesophagus.
Discuss anatomical relations
Anatoical relations can be discussed bases on the segments of the oesophagus.They include the cervical and thoracic segment and the abdominal segment.
Cervical and thoracic segment relations.
Anterior-Trachea.
Left recurrent laryngeal
nerve
Pericardium
Posterior-Thoracic vertebral
bodies
Thoracic duct
Azygous veins
Descending aorta
Left- Subclavian artery
Aortic arch
Thoracic duct
Pleura
Right-Pleura
Terminal part of azygous
vein
Abdominal segment relations
Anterior- Left vagus nerve
Posterior surface of the
heart
Posterior- Right vagus nerve.
Left crus of
diaphragm.
Arterial supply
Cervical and thoracic part-Branches of thoracic aorta.
Inferior thyroid artery.
Abdominal part-Left gastric artery.
Left phrenic artery.
The abdominal part of oesophagus has a mixed venous drainage via two 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.
Innervation
The oesophagus is innervated by the oesophageal plexus.
It is formed by a combination of the parasympathetic vagal trunks and sympathetic fibres from the cervical and thoracic sympathetic trunks.
Venous drainage
Upper part of the oesophagus drains
into the brachiocephalic veins.
Middle part drains into the azygos veins
Lower part drains into the left gastric vein and azygos vein.
Lypmhatics
Superior third – deep cervical lymph nodes.
Middle third – superior and posterior mediastinal nodes.
Lower third – left gastric and celiac nodes.
Clinical correlates
Barretts oesophagus
Oesophageal varices.
Achalasia cardia
Dysphagia
Barretts oesophagus
It refers to the metaplasia of lower oesophageal squamous epithelium to gastric columnar epithelium.
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.
Dysphagia(Difficulty in Swallowing).
It is caused by hardening of the muscular layers of the oesophagus. It interferes with peristalsis and cause difficulty in swallowing.
Constrictions of the oesophagus
The oesophagus shows four constrictions.
1.At the start of the esophagus, where the laryngopharynx joins the esophagus, behind the cricoid cartilage.
2.Where it is crossed on the front by the aortic arch in the superior mediastinum.
3.Where the esophagus is compressed by the left main bronchus in the posterior mediastinum.
4.The esophageal hiatus, where it passes through the diaphragm in the posterior mediastinum.
Oesophageal varices
In portal hypertension, the communications
between the portal and systemic veins draining
the lower end of the oesophagus dilate( left gastric vein and azygos vein).
These dilatations are called oesophageal varices. Rupture
of these varices can cause serious haematemesis
or vomiting of blood. The oesophageal varices can
be visualised radiographically by barium swallow.
Achalasia cardia
The condition
of neuromuscular incoordination characterised by inability of the oesophagus to dilate is known
as ‘achalasia cardia’. It may be due to congenital
absence of nerve cells in wall of oesophagus.
Due to failure of oesophagus to dilate, food accumulates.
