The cricothyroid space: topography and clinical implications

The inferior border of the thyroid cartilage and the superior rim of the cricoid arch are connected by the cricothyroid membrane and partly covered by the cricothyroid muscles ventrally. This region has been termed the cricothyroid space (CS) and is important with regard to surgical procedures, the spread of laryngeal cancer and traumatic lesions of the larynx. The precise topographic relations of the CS were investigated in plastinated serial sections of 21 normal adult human specimens. The CS consists of a caudal and a cranial portion, which are different with regard to their cartilaginous framework and their relationship to intralaryngeal structures. The caudal portion is bordered by the cricoid cartilage and reveals a complete separation of extra- and intralaryngeal regions by the cricothyroid membrane. It provides an easy access to the subglottic airways. The cranial portion of the CS is mainly bordered by the thyroid cartilage. It is characterized by a gap lateral to the median cricothyroid ligament. This allows a connection of extra- and intralaryngeal adipose tissue. There, extralaryngeal extension of laryngeal cancer preferentially occurs. Traumatic subglottic ruptures of the larynx involve both the caudal and cranial portions of the CS, which often results in extensive scar tissue formation.