Anatomy of Oesophagus
The oesophagus is a fibromuscular tube approximately 25 cm long in adults, extending from the lower end of the pharynx (C6) to the stomach’s cardiac end (T11). It runs vertically downwards with slight leftward inclinations at the thoracic inlet and near the diaphragm (T7-T10). It passes behind the trachea, traverses the superior and posterior mediastina of the thorax, and enters the stomach.
Subdivisions of the Oesophagus
The oesophagus is anatomically divided into three distinct segments: cervical, thoracic, and abdominal. Each segment has specific boundaries and landmarks critical for clinical assessment and surgical interventions.
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Cervical Segment. The cervical segment begins at the lower border of the cricoid cartilage (C6) and extends up to the thoracic inlet or suprasternal notch (T2-T3). This segment is relatively shorter and closely related to the trachea anteriorly and the vertebral column posteriorly. Its proximity to critical structures, such as the recurrent laryngeal nerve and major blood vessels, makes it important in trauma and surgical contexts.
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Thoracic Segment. The thoracic segment spans from the suprasternal notch (T2-T3) down to the diaphragm (T10). It is the longest segment of the oesophagus, travelling through the mediastinum, posterior to the heart and anterior to the vertebral column. The thoracic oesophagus passes through the chest cavity and encounters important structures like the aorta, bronchi, and pleura. It is prone to disorders such as oesophageal perforation or rupture, especially near the diaphragm. This segment also includes the lower oesophageal sphincter, which is crucial in preventing gastroesophageal reflux.
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Abdominal Segment. The abdominal segment is the shortest segment of the oesophagus, running from the diaphragm (T10) to the fundus of the stomach (T11). It crosses the oesophageal hiatus of the diaphragm and enters the abdomen. This segment is vital for the transition of food from the oesophagus into the stomach. Conditions like hiatus hernia or gastroesophageal reflux disease (GERD) are often associated with dysfunction in this area. It is also the location where surgeries such as fundoplication are performed to address reflux issues.
Constrictions of the oesophagus.
The oesophagus has three normal constrictions which are important for oesophagoscopy. These constrictions have important clinical consequences. For example, a swallowed object is most likely to lodge at a constricted area. An ingested corrosive substance would move more slowly through a narrowed region, causing more damage at this site than elsewhere along the oesophagus. Also, constrictions present problems during the passage of medical instruments. The three normal constrictions are:
- At pharyngo-oesophageal junction (C6) – 15 cm from the upper incisors.
- At the crossing of the arch of aorta and left main bronchus (T4) – 25 cm from upper incisors.
- Where it pierces the diaphragm (T10) – 40 cm from the upper incisors.
Walls of the oesophagus
The wall of the oesophagus consists of four layers. From within outwards, they are:
- Mucosa, is lined by stratified squamous epithelium (greyish-pink and smooth), which changes to columnar epithelium (reddish-pink) in the lower oesophagus when it enters the stomach.
- Submucosa, which loosely connects mucosa to the muscular layer.
- The muscular layer has inner circular and outer longitudinal fibres. Circular fibres at the lower end are thickened to form a cardiac sphincter. The upper third of the oesophagus is striated, the lower third is smooth, and the middle third has both striated and smooth muscle fibres.
- The fibrous layer (adventitial layer) forms a loose covering of the oesophagus. It consists of the adventitia and dense connective tissue with elastin fibres and also contains small vessels, nerve fibres, and lymphatic channels.
Blood Supply:
- Arterial supply: The cervical segment is supplied by inferior thyroid artery, the thoracic segment by thoracic aorta and the abdominal segment by the left gastric artery and left inferior phrenic arteries.
- Venous drainage: The cervical segment drains into inferior thyroid vein, the thoracic segment drains into azygos vein and the abdominal segment drains into the left gastric vein.
Nerve Supply:
- Parasympathetic fibres: Vagus nerves.
- Sympathetic fibres: Sympathetic trunk.
Lymphatic Drainage:
- Cervical region: Lower deep cervical and paratracheal and upper mediastinal nodes.
- Thoracic region: Posterior mediastinal nodes and the tracheobronchial nodes.
- Abdominal region: Left gastric nodes and coeliac nodes.
Relations of the oesophagus
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Anatomy of Oesophagus Best Lecture Notes Dr Rahul Bagla ENT Textbook
Reference Textbooks.
- Scott-Brown, Textbook of Otorhinolaryngology-Head and Neck Surgery.
- Cummings, Otolaryngology-Head and Neck Surgery.
- Stell and Maran’s, Textbook of Head and Neck Surgery and Oncology.
- Ballenger’s, Otorhinolaryngology Head And Neck Surgery
- Susan Standring, Gray’s Anatomy.
- Frank H. Netter, Atlas of Human Anatomy.
- B.D. Chaurasiya, Human Anatomy.
- P L Dhingra, Textbook of Diseases of Ear, Nose and Throat.
- Hazarika P, Textbook of Ear Nose Throat And Head Neck Surgery Clinical Practical.
- Mohan Bansal, Textbook of Diseases of Ear, Nose and Throat Head and Neck Surgery.
- Hans Behrbohm, Textbook of Ear, Nose, and Throat Diseases With Head and Neck Surgery.
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- Arnold, U. Ganzer, Textbook of Otorhinolaryngology, Head and Neck Surgery.
- Ganong’s Review of Medical Physiology.
- Guyton & Hall Textbook of Medical Physiology.
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