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Topic

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Trachea

The trachea is a fibrocartilaginous and membranous tube forming the main airway, extending from the cricoid cartilage (C6 vertebral level) to its bifurcation at the carina (T4–T5 level), where it divides into the right and left main bronchi. It is approximately 10–12 cm in length and 2–2.5 cm in diameter in adults. The tracheal wall consists of C-shaped hyaline cartilage rings anteriorly and laterally, with the posterior wall formed by the trachealis muscle. The lumen is lined by respiratory epithelium (ciliated pseudostratified columnar epithelium with goblet cells), specialized for mucociliary clearance.

The trachea lies in the midline of the neck and upper thorax, anterior to the esophagus and posterior to the thyroid and great vessels. It serves as the primary conduit for air passage to the lungs, maintaining patency through rigid cartilage rings.

Synonyms

  • Windpipe

  • Tracheal airway

  • Main airway conduit

Function

  • Provides a rigid, patent airway for respiration

  • Conducts inspired and expired air between the larynx and bronchi

  • Filters, warms, and humidifies inhaled air via the mucociliary escalator

  • Participates in cough reflex and airway defense mechanisms

Nerve Supply

  • Parasympathetic innervation: from the vagus nerve (CN X) via tracheal branches

  • Sympathetic innervation: from the cervical and upper thoracic sympathetic trunks

  • Provides motor innervation to the trachealis muscle and sensory innervation to mucosa

MRI Appearance

T1-weighted images:

  • Lumen normally contains air (signal void, black)

  • Tracheal wall appears low to intermediate signal intensity

  • Surrounding fat is hyperintense, helping outline tracheal contours

T2-weighted images:

  • Lumen remains a signal void

  • Tracheal wall is intermediate signal, while inflammation or edema appears hyperintense

  • Fluid or mucus within the lumen appears bright hyperintense

STIR (Short Tau Inversion Recovery):

  • Fat suppression improves visualization of wall edema, thickening, or mediastinal extension

  • Normal wall is low signal

  • Pathology (tracheitis, tumor infiltration, acute injury) appears hyperintense

T1 Post-Contrast (Gadolinium-enhanced):

  • Normal tracheal wall enhances mildly and homogeneously

  • Pathological changes (tumor, infection, granulation tissue) demonstrate heterogeneous or nodular enhancement

CT Appearance

Non-contrast CT:

  • Trachea appears as an air-filled (black, hypodense) tubular structure extending from C6 to T4–T5

  • Tracheal wall appears as a thin soft tissue density ring

  • Cartilaginous rings appear as slightly hyperdense semicircular structures

Contrast-enhanced CT (CECT):

  • Highlights the tracheal wall and adjacent mediastinal structures

  • Detects tracheal stenosis, wall thickening, tumors, foreign bodies, or tracheomalacia

  • Provides excellent spatial resolution of airway caliber and cartilage integrity

MRI images

Trachea MRI coronal image -img-00000-00000

CT image

Trachea chest coronal ct image -img-00000-00000

X Ray image

Trachea X ray anatomy image -img-00000-00000