Trachea Structure and Function

Trachea Structure

• The trachea, commonly known as the windpipe, is a tube that connects the larynx to the bronchi, forming the beginning of the lower respiratory tract.
• It's composed of C-shaped cartilaginous rings, with a membranous posterior part enabling esophageal expansion during swallowing.
• The trachea stretches about 4-6 inches, with the upper half located in the neck and the lower half in the superior mediastinum.
• The lumen of the trachea is smaller in living individuals compared to cadavers.
• Starting at the lower border of the cricoid cartilage (C6), it continues from the larynx and ends at the lower border of T4 (sternal angle) where it divides into two principal bronchi.
• In upright individuals, the trachea bifurcates at the lower border of T6.
• The trachea is generally located in the median plane with a slight deviation to the right at its lower end.
• It develops from the laryngo-tracheal diverticulum.

Trachea Wall Structure

• The trachea's wall is composed of fibro-elastic tissue supported by a C-shaped cartilaginous skeleton.
• The trachea contains 16-20 cartilaginous rings, the last one known as carina.
• The gap in the C-shaped rings is closed by a fibro-elastic membrane and trachealis muscle.
• The trachea’s mucous membrane is lined with ciliated columnar epithelium.
• The submucosa is rich in mucous and serous glands.

Trachea Blood Supply and Drainage

• The cervical part of the trachea receives blood supply from branches originating from the inferior thyroid artery.
• Venous drainage occurs into the left brachiocephalic vein.

Trachea Lymphatic System

• The trachea's lymphatic drainage is through pretracheal and paratracheal lymph nodes.

Trachea Nerve Supply

• Parasympathetic innervation is provided by the recurrent laryngeal nerve, a branch of the vagus nerve. This nerve controls the trachealis muscle and the secretion of the mucous membrane.
• Sympathetic innervation originates from the middle cervical sympathetic ganglion, reaching the trachea via inferior thyroid arteries, and acts as a vasomotor (regulates blood vessel diameter).