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In anatomy the trachea, or windpipe, is a tube that connects the pharynx and larynx to the lungs, allowing the passage of air.[1] It is lined with pseudostratified ciliated columnar epithelium cells with goblet cells that produce mucus. This mucus lines the cells of the trachea to trap inhaled foreign particles that the cilia then waft upward toward the larynx and then the pharynx where it can be either swallowed into the stomach or expelled as phlegm.

Despite the name, not all vertebrates have a trachea; only non-fish ones. The name is used in contrast with invertebrate trachea, a structure in arthropod anatomy.[2]

In humans[]

In humans, the trachea passes ventrally to the esophagus, dorsally to the ascending aortic arch, but the left main bronchus that the trachea gives off passes ventrally to the descending aortic arch. The trachea has an inner diameter of about 25 millimetres (1.0 in) and a length of about 10 to 16 centimetres (4 to 6 in). It commences at the lower border of the larynx, level with the sixth cervical vertebra, and bifurcates into the primary bronchi at the vertebral level of thoracic vertebra T5, or up to two vertebrae lower or higher, depending on breathing.

There are about fifteen to twenty incomplete C-shaped cartilaginous rings that reinforce the anterior and lateral sides of the trachea to protect and maintain the airway, leaving a membranous wall (pars membranacea) dorsally without cartilage. The trachealis muscle connects the ends of the incomplete rings and contracts during coughing, reducing the size of the lumen of the trachea to increase the air flow rate. The esophagus lies posteriorly to the trachea. The cartilaginous rings are incomplete to allow the trachea to collapse slightly so that food can pass down the esophagus. A flap-like epiglottis closes the opening to the larynx during swallowing to prevent swallowed matter from entering the trachea. Lined with respiratory epithelium.

References[]

  1. Romer, Alfred Sherwood; Parsons, Thomas S. (1977). The Vertebrate Body. Philadelphia, PA: Holt-Saunders International. pp. 336–337. ISBN 0-03-910284-X.
  2. Romer, Alfred Sherwood; Parsons, Thomas S. (1977). The Vertebrate Body. Philadelphia, PA: Holt-Saunders International. pp. 336–337. ISBN 0-03-910284-X.

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