Trachea
Trachea · C6 to T4/5 16-20 rings Generation 0
Fibrocartilaginous tube running from the cricoid cartilage (C6) to the carina at the sternal angle (T4/5), about 10 to 12 cm long and 2 cm wide. It is held open by 16 to 20 C-shaped hyaline cartilages whose posterior gap is closed by the trachealis muscle, which lies directly against the oesophagus.
Detail
- Extent
- C6 (lower border of cricoid) to the carina at the sternal angle, T4/5; descends a vertebral level or more on deep inspiration
- Wall
- 16 to 20 C-shaped hyaline cartilage rings, trachealis smooth muscle closing the posterior gap, submucosal seromucous glands
- Epithelium
- Pseudostratified ciliated columnar with goblet cells (respiratory epithelium); cilia beat towards the larynx, the mucociliary escalator
- Relations
- Thyroid isthmus over rings 2 to 4, inferior thyroid veins, then brachiocephalic trunk and left brachiocephalic vein in front; oesophagus behind; recurrent laryngeal nerves in the tracheo-oesophageal grooves; aortic arch on the left
- Supply
- Inferior thyroid arteries (cervical part) and bronchial arteries (thoracic part); recurrent laryngeal (vagus) and sympathetic fibres; lymph to pretracheal, paratracheal and deep cervical nodes
When it goes wrong
Tension pneumothorax or massive pleural effusion
Trachea deviated away from the affected side; lobar collapse or fibrosis pulls it towards the lesion
Tracheostomy
Placed through rings 2 to 4 below the thyroid isthmus; the first ring is spared to avoid subglottic stenosis; inferior thyroid veins, and in children the high brachiocephalic trunk, are at risk of haemorrhage
Chronic bronchitis in a smoker
Hyperplasia of the submucosal mucous glands of trachea and bronchi; Reid index (gland to wall thickness) above 0.4; productive cough on most days for 3 months in 2 consecutive years
Primary ciliary dyskinesia (Kartagener syndrome)
Immotile cilia stop the mucociliary escalator: recurrent sinusitis and chest infection, bronchiectasis, situs inversus and male infertility
Practise this structure
3 questions in the bank tagged Thorax.
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