Two dense capillary networks have been described lying in the anterior and posterior parts of the human cricoid cartilage. Between these two lies an area supplied by a very sparse capillary network. The anterior sector is derived from branches of the cricothyroid and inferior laryngeal arteries, the posterior from branches of the superior and inferior laryngeal arteries. The tracheal cartilages are supplied from above downwards by circular branches derived from two parallel longitudinal arteries. Therefore the centre of each cartilage is very sparsely supplied by small arteries.