Key nob appearance is seen in:
|D||Vocal cord paralysis|
Phonoasthemia is weakness of voice due to fatigue of phonatory muscles. either thyroarytenoids or intrarytenoids or both O/E - on Indirect laryngoscopy - 3 features may be seen
Elliptical space between the cords in case of weakness of thyroarytenoid
Triangular gap near posterior commissure in weakness of interarytenoid
Keyhole appearance of glottis when both thyroarytenoids are involved.