Clinical Histoanatomy around Anterior Commissure for Type II Thyroplasty Success

When Type Ⅱ thyroplasty is performed, surgical management of the dihedral angle of the midline of the thyroid cartilage is very important. Clinical histoanatomy around the anterior commissure was investigated using whole organ serial sections of the human larynx to make Type Ⅱ thyroplasty successful. An inner perichondrium did not exist at the dihedral angle in the upper three-forths of the midline of the thyroid cartilage. On the other hand, the inner perichondrium was present at the lower one-forth of the midline of the posterior surface of the thyroid cartilage. The attachment of the collagenous fiber （anterior commissure tendon, Broyles, 1943） extends from the upper portion of the thyroid notch caudalward for approximately upper three-forths of the midline of posterior surface of the thyroid cartilage. The midline of the posterior surface of the thyroid cartilage is only covered with thin mucosa at the laryngeal ventricle level. It is important not to perforate the mucosa when the laryngofissure is performed. In order to make the anterior commissure the proper width, it is important to split the anterior commissure tendon at the mid-line and to spread the glottis while making sure the tendons remain attached to the bilateral thyroid cartilage.