Translation and rotation of the cricothyroid joint revealed by phonation-synchronized high-resolution MRI

The action of the cricothyroid joint for regulating voice fundamental frequency is thought to have two components; rotation and translation. Its empirical verification, however, has faced methodological problems. This study examines the joint action by means of a phonation-synchronized high-resolution Magnetic Resonance Imaging (MRI) technique, which employs two technical improvements; a custom laryngeal coil to enhance image resolution and an external triggering method to synchronize the subject’s phonation and MRI scan. The obtained images were clear enough to demonstrate two actions of the joint; the cricoid cartilage rotates 5 degrees and the thyroid cartilage translated 1.25 mm in the range of half an octave.