Cricoid cartilage

The cricoid cartilage is a ring of cartilage that encircles the trachea just below the Adam's apple (part of the thyroid cartilage).

It is named due to it's resemblance to a signet ring, using the greek word Kpikos. Although smaller than the thyroid cartilage, the cricoid cartilage is much stronger and thicker and made of hyaline cartilage. The cartilage is made up of two parts, a narrow ring that sits at the front and a quadrate portion that is found behind the ring.

Portions of the Cricoid Cartilage
There are two main portions that make up the cricoid cartilage. The first is called the posterior portion which is approximately 3 centimetres in size. It is broad and has a vertical ridge on the posterior surface to allow attachment of the longitudinal fibres of the oesophagus. A depression lies either side of the vertical ridge for the Crico-arytenoideus posticus muscle.

The anterior portion differs for it is narrow and measures 0.7 centimetres in size. It provides attachment for front and sides of the crico-thyroid muscles and also offers attachment to the inferior constrictor.

Function
The main role of the Cricoid cartilage is to act as an attachment for muscles and other cartilage fibres that are involved in opening and closing the airway. These are also involved in speech production.