Thoracic Oesophagus — Extent, Position and Course
Overview
The oesophagus is a muscular tube approximately 25 cm long in adults, extending from the cricoid cartilage (C6 vertebra) to the stomach. It is divided into three parts: cervical, thoracic, and abdominal.
The thoracic part is the longest segment, extending from the thoracic inlet (T1) to the oesophageal hiatus in the diaphragm (T10).
Extent of the Thoracic Oesophagus
| Boundary | Level |
|---|---|
| Upper end (begins) | Thoracic inlet — at the level of T1 vertebra |
| Lower end (ends) | Oesophageal hiatus in the diaphragm — at T10 vertebra, 2–3 cm to the left of the median plane |
Position and Course
The thoracic oesophagus passes through two mediastinal compartments:
In the Superior Mediastinum (T1–T4)
- Lies between the trachea anteriorly and the vertebral column posteriorly
- Slightly to the left of the median plane
- The left recurrent laryngeal nerve runs in the groove between the trachea and the oesophagus on the left side
At the Junction of Superior and Posterior Mediastinum (T4–T5)
- Enters the posterior mediastinum by passing behind the left principal bronchus and right pulmonary artery (at the level of the tracheal bifurcation — T4/5)
- Posterior to the left atrium (separated from it by the oblique sinus of the pericardium)
In the Posterior Mediastinum (T5–T10)
- Descends in the posterior mediastinum posterior to the left atrium
- Initially lies slightly to the right, then inclines progressively to the left as it approaches the diaphragm
- At the level of T7 onwards, the oesophagus lies anterior to the descending thoracic aorta (the aorta moves posteriorly and rightward while the oesophagus moves leftward and anteriorly — they cross at approximately T7)
- Passes through the right crus of the diaphragm at the oesophageal hiatus (T10), 2–3 cm to the left of the median plane
Summary of Course
| Level | Position | Key Relationships |
|---|---|---|
| T1–T4 (Superior mediastinum) | Left of midline, between trachea and vertebral column | Left recurrent laryngeal nerve in left tracheo-oesophageal groove |
| T4–T5 | Enters posterior mediastinum | Crosses behind left bronchus and right pulmonary artery |
| T5–T7 | Posterior to left atrium | Left atrium separated by oblique sinus |
| T7–T10 | Inclines left, anterior to descending aorta | Oesophagus and aorta cross: oesophagus moves left, aorta moves right |
| T10 | Passes through oesophageal hiatus | Right crus of diaphragm, left of midline |
Oesophageal Hiatus
- Located in the right crus of the diaphragm at the level of T10
- The fibres of the right crus split and encircle the oesophagus — acting as a physiological sphincter (lower oesophageal sphincter)
- 2–3 cm to the left of the median plane
- Structures passing through: oesophagus, right and left vagal trunks, oesophageal branches of the left gastric artery