The
oesophagus is a fibromuscular tube, approximately 25cm in length, that
transports food from the pharynx to the stomach.
It originates at the inferior border of the cricoid cartilage (C6) and extends to the
cardiac orifice of the stomach (T11).
Anatomical Course
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.
The abdominal portion of the oesophagus is approximately 1.25cm long – it
terminates by joining the cardiac orifice of the stomach at level of T11.
Anatomical Structure
Adventitia – outer layer of connective tissue. Muscle layer – external layer of
longitudinal muscle and inner layer of circular muscle. The external layer is
composed of different muscle types in each third:
Superior third – voluntary striated muscle
Middle third – voluntary striated and smooth muscle
Inferior third – smooth muscle
Submucosa
Mucosa – non-keratinised stratified squamous epithelium (contiguous with columnar
epithelium of the stomach).
Food is transported through the oesophagus by peristalsis – rhythmic contractions of
the muscles which propagate down the oesophagus.
Oesophageal Sphincters
There are two sphincters present in the oesophagus, known as the upper and lower
oesophageal sphincters.
Upper Oesophageal Sphincter
The upper sphincter is an anatomical, striated muscle sphincter at the junction
between the pharynx and oesophagus. It is produced by
the cricopharyngeus muscle.
Lower Oesophageal Sphincter
The lower oesophageal sphincter is located at the gastro-oesophageal
junction (between the stomach and oesophagus). The gastro-oesophageal junction is
situated to the left of the T11 vertebra,
Vasculature
In respect to its arterial and venous supply, the oesophagus can be divided into its
thoracic and abdominal components.
Thoracic
The thoracic part of the oesophagus receives its arterial supply from the branches of
the thoracic aorta and the inferior thyroid artery (a branch of the thyrocervical
trunk).
Venous drainage into the systemic circulation occurs via branches of the azygous
veins and the inferior thyroid vein.
Abdominal
The abdominal oesophagus is supplied by the left gastric artery (a branch of the
coeliac trunk) and left inferior phrenic artery. This part of the 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, a connection between the
portal and systemic venous systems.
Innervation
The oesophagus is innervated by the oesophageal plexus, which is formed by a
combination of the parasympathetic vagal trunks and sympathetic fibres from
the cervical and thoracic sympathetic trunks.
Lymphatics
The lymphatic drainage of the oesophagus is divided into thirds:
Superior third – deep cervical lymph nodes.
Middle third – superior and posterior mediastinal nodes.
Lower third – left gastric and celiac nodes.
