Trachea is a flexible, cartilage-supported airway that connects the larynx, or voice box, to the main bronchi, the air passages entering the lungs. It lies in the lower neck and upper chest, in front of the oesophagus, and conducts air as part of the respiratory system.
Where is the trachea located?
The trachea begins at the lower border of the cricoid cartilage, the complete cartilage ring at the base of the larynx. It descends through the neck and enters the superior mediastinum, the central compartment of the upper chest between the lungs.
The oesophagus, the muscular tube carrying swallowed material towards the stomach, lies immediately behind it. In the neck, the thyroid isthmus—the bridge joining the thyroid gland’s lobes—crosses the front of the trachea. The thyroid lobes lie on either side, and the strap muscles, a group of flat muscles in the front of the neck, lie further anteriorly.
In the chest, the left brachiocephalic vein passes in front of the trachea. The aortic arch, the curved part of the main artery leaving the heart, lies to its left. These relationships help distinguish the airway from neighbouring vessels when viewing the neck and chest together.
What are the parts of the trachea?
The trachea has a cervical portion in the neck and a thoracic portion in the chest. These are continuous regions of the same tube, not separate chambers. Its lower end divides into the right and left main bronchi, continuing the branching tracheobronchial tree, which includes the trachea itself.
At this division, the carina of trachea forms an internal ridge between the bronchial openings. The right main bronchus is generally wider, shorter and more vertical than the left main bronchus.
The trachea has a rounded front and sides, but a flatter posterior wall. Its position and direction are not rigidly fixed: its flexible connections allow movement with breathing and movements of the neck.
What is the tracheal wall made of?
The trachea cartilage consists of C-shaped supports made of hyaline cartilage, a firm connective tissue with a smooth, glassy matrix. Their open ends face backwards towards the oesophagus. Fibrous connective tissue joins neighbouring cartilage supports and allows the tube to bend.
The posterior gap is bridged by a flexible wall containing the trachealis muscle. This is smooth muscle, meaning muscle controlled without conscious effort. The trachea lumen is the open internal passage through which air flows.
| Wall feature | Structure | Anatomical role |
|---|---|---|
| Cartilage supports | C-shaped hyaline cartilage | Support the front and sides of the airway |
| Posterior wall | Connective tissue and trachealis muscle | Allows flexibility behind the lumen |
| Inner lining | Mucus-producing cells and ciliated cells | Traps material and moves it towards the throat |
| Outer covering | Connective tissue continuous with surrounding tissues | Connects the trachea to neighbouring structures |
The mucosa, or moist inner lining, contains an epithelium: a sheet of closely packed surface cells. Most of this lining is pseudostratified ciliated columnar epithelium, which appears layered although its cells share a common supporting base. Its ciliated columnar cells bear cilia, tiny moving surface projections, while goblet cells produce mucus.
Beneath the mucosa, the submucosa is a supporting tissue layer containing glands, vessels and nerves. Its glands also contribute secretions to the airway surface.
What does the trachea do?
The trachea conducts air between the larynx and the bronchi. Its cartilage resists narrowing during breathing, while its flexible wall accommodates movement. The trachea is not a site of gas exchange; that occurs mainly in the alveoli, the microscopic air sacs of the lungs.
Mucus traps inhaled particles, and coordinated ciliary movement carries this material towards the throat. This transport is called mucociliary clearance. The trachealis muscle can narrow the lumen, contributing to the movement of air during coughing.
The flexible posterior wall also accommodates expansion of the oesophagus as swallowed material passes behind the trachea. This relationship explains why cartilage does not form complete rings around the airway.
What supplies blood to the trachea?
The cervical portion receives blood mainly through the tracheal branches of inferior thyroid artery. The thoracic portion receives branches from the bronchial arteries, which also supply supporting tissues of the bronchi. Small arterial connections link neighbouring areas along the tracheal wall.
Venous blood from the cervical trachea drains into the inferior thyroid veins and then towards the brachiocephalic vein, a large vein returning blood from the neck and upper limb. The thoracic portion also drains through bronchial veins.
What are the nerve supply and lymph drainage?
The trachea receives autonomic nerves, which regulate involuntary activity in its muscle and glands. Parasympathetic fibres reach it through the vagus nerves, including their recurrent laryngeal branches. Sympathetic fibres arrive from the sympathetic trunks, chains of nerve ganglia alongside the vertebral column; ganglia are collections of nerve-cell bodies outside the brain and spinal cord.
Sensory fibres carry information from the tracheal lining and contribute to the cough reflex. The recurrent laryngeal nerves ascend close to the grooves between the trachea and oesophagus.
Lymph, fluid collected from tissues, drains towards regional lymph nodes. These include pretracheal nodes in front of the trachea, paratracheal nodes beside it, and tracheobronchial nodes near its division. Upper pathways also communicate with deep cervical nodes in the neck.
How can you find the trachea in the 3D model?
In the 3D model next to this article, rotate and zoom to orient your view, then select and isolate the trachea. Switch layers to change your view, and hide or fade structures to adjust their visibility. Cut a section along the sagittal, coronal or transverse plane for a different view. You can also pull parts apart, then rotate and zoom again to examine the selected region from another angle.