A sound is created as a result of several breathing, phonetic and articulation positions and movements which take place in the articulation system consisting of both mobile and immobile elements. The tongue is one of the mobile elements of the articulation system. Full range of tongue mobility is required to form sounds correctly. If mobility of the tongue is reduced, sounds may slightly, moderately or highly deviate from proper ones. Serious deviations in articulate structure of sounds (such as non-vibrating front part of the tongue in the /r/ phoneme) are easy to notice since they change phoneme structure of the sound. Slight deviations (e.g. non-vibrational or non-mediumistic action of the tongue) may be unnoticed because speech is still comprehensible although it is formed with compensatory positions and movements of breathing, phonetic and articulation apparatus. There are some phonemes that require a wide range of tongue mobility to be formed correctly, while others require less tongue mobility. In the Polish language, phonemes that require the most mobile tongue are: trembling /r/, lateral /l/, humming /sz, z, cz, dz/, and soft /i, j, ś, ź, ć, dź/. In order to diagnose abnormalities, organs of speech need to be observed directly (photographs, films) or indirectly (videoradiography). One of the factors that restrict (to a slight, average or high degree) tongue mobility is the short frenulum. According to the general opinion "the tongue frenulum has no influence on tongue mobility". However, persons with ankyloglossia form at least one of the above-mentioned phonemes incorrectly to a slight, medium or high degree and frenotomy is required to make improvement of speech by a speech therapist effective. In opinion of many physicians and speech therapists " frenotomy is usually pointless because a new scar is formed that makes the frenulum even shorter than before". I have found in my research that tongue mobility improves after each frenotomy and no adhesions are formed after simple horizontal cutting of the frenulum with scissors (local anesthesia) if the wound is not sutured. It is often necessary to carry out several frenotomies to achieve full articulating mobility of the tongue.