The cricothyroid membrane (conus elasticus anterior portion, or median cricothyroid ligament) is the midline fibroelastic membrane spanning from the superior border of the cricoid cartilage to the inferior border of the thyroid cartilage in the anterior laryngeal midline. It is palpable in the midline as the firm yielding structure between the thyroid cartilage notch (above) and the cricoid cartilage (below), covered only by thin skin, subcutaneous tissue, and the cricothyroid muscles laterally.
Forms the anterior wall of the subglottic airway; provides the emergency airway access route between the thyroid and cricoid cartilages; serves as the structural membrane for the anterior subglottic larynx connecting the cricoid to the thyroid cartilages in the midline.
The cricothyroid membrane is the target for emergency cricothyrotomy in cannot-intubate cannot-oxygenate (CICO) airway emergencies. The 4C approach (Cricothyroid Catheter and Cannula or Cutter — open surgical cricothyrotomy) uses the membrane as the incision site: palpating the thyroid notch, sliding the fingers inferiorly to the CTM, horizontal stab incision through membrane, then dilation. In elective situations, cricothyrotomy is used for transtracheal jet ventilation and percutaneous tracheostomy placement. Permanent high tracheostomy through the CTM produces subglottic stenosis and is avoided.
In CICO airway emergency where intubation and mask ventilation have failed, surgical cricothyrotomy through the palpable cricothyroid membrane with scalpel-finger-tube technique (No. 10 blade horizontal stab, digital dilation, cuffed 6.0 ET tube insertion) provides immediate oxygenation within 30-60 seconds; this technique has replaced needle cricothyrotomy in adult airway emergency protocols.
