cricothyroid

Cricothyroid refers to structures in the larynx associated with the cricothyroid region, most notably the cricothyroid muscle and the cricothyroid membrane. It is a key component of voice production and airway anatomy.

The cricothyroid muscle is one of the intrinsic muscles of the larynx. It originates from the anterior cricoid arch and inserts into the lower border and angle of the thyroid cartilage. The muscle is typically described as having two parts, and it acts to tense the vocal cords. It shortens the distance between the thyroid and cricoid cartilages, tilting the thyroid cartilage forward relative to the cricoid, thereby lengthening and stretching the vocal cords and increasing pitch. The cricothyroid muscle is innervated by the external branch of the superior laryngeal nerve, a branch of the vagus nerve. Blood supply is via branches of the superior thyroid artery.

The cricothyroid membrane, or median cricothyroid ligament, spans the space between the cricoid and thyroid cartilages at the anterior larynx. This fibrous structure is part of the cricothyroid region and forms a relatively thin, clinically important area. In emergency airway management, the cricothyroid membrane is the usual entry point for a cricothyrotomy, allowing rapid access to the trachea when other routes are obstructed.

Clinical relevance includes its role in modulating voice pitch and its importance in airway procedures. Injury to the external branch of the superior laryngeal nerve can affect pitch control, while procedures involving the cricothyroid membrane require careful technique to avoid injury to surrounding laryngeal structures.