Anatomy, Physiology, and Pathology of the Hearing, Vision, and Speech Organs - Shvetsov A.G. 2006

Anatomy, Physiology, and Pathology of Voice and Speech Production
Pathology of Voice Production
Pathology of the Articulatory Apparatus

Among Oral Cavity disorders, Developmental anomalies of the articulatory Organs—the Lips, Hard and Soft palate, Tongue, jaws, and Teeth—have the greatest practical significance regarding their impact on voice and speech production.

The most common developmental Anomalies of the lips and palate are cleft defects of the upper lip and palate, which result from delayed fusion of the embryonic processes that form these PARTS OF THE oral cavity. The mildest form is a unilateral cleft lip ('harelip'), while the most severe is a complete cleft of the lip, alveolar process, and palate ('cleft palate').

Congenital oral defects also include a shortened soft palate, a shortened or completely absent uvula, and a narrow, abnormally high ('gothic') palate.

The most pronounced speech defects are undoubtedly associated with a cleft palate: speech acquires a nasal quality, becomes muffled and indistinct, and there is impairment in the pronunciation of both consonants and vowels (complete nasalization). With other congenital anomalies of the lip and palate, their manifestation in speech is less severe, though still noticeable.

The tongue is the primary articulatory organ, and its developmental defects significantly hinder the acquisition of speech sound production. Anomalies of tongue development primarily include its complete absence, or aglossia; underdevelopment of the tongue (microglossia); or an abnormally large tongue (macroglossia). A relatively common developmental defect is congenital tongue-tie (ankyloglossia), or a shortened lingual frenulum. In this condition, tongue movements can be restricted because an excessively short frenulum tethers it to the floor of the Mouth, impairing its articulatory function.

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Fig. 22. Normal occlusion

Rare anomalies include a bifid tongue (cleft tongue), which is sometimes associated with cleft lip and palate.

Developmental defects of the jaws and dentition most commonly manifest as malocclusions. Occlusion refers to the spatial relationship between the upper and lower dental arches when the jaws are closed (Fig. 22).

In a normal jaw and dental Structure, the upper dental arch is slightly larger than the lower one, so that when the jaws close, the lower front teeth are slightly overlapped by the upper ones, with all the teeth of the upper front row making contact with the teeth of the lower row.

Impaired speech sound pronunciation, especially in children, is caused by various structural defects of the jaws that lead to malocclusions:

§ prognathism—where the upper jaw protrudes significantly forward;

§ progenia—where the lower jaw protrudes forward;

§ anterior open bite—where a gap remains between the upper and lower teeth when closed;

§ lateral open bite—where a gap remains when the posterior teeth are closed.

Improper pronunciation is also caused by abnormal tooth structure, such as large gaps between teeth, missing teeth, altered tooth shape, or deformed edges. Anomalies in the dental arch manifest as crooked teeth, teeth positioned outside the dental arch, supernumerary teeth, etc. All structural and positional defects of the teeth are most commonly accompanied by pronunciation disorders in the form of lisping.

Impairment of normal lip and cheek mobility is typically observed in cases of Facial Nerve damage. One cause of facial nerve damage is Middle ear inflammation, as the facial nerve passes through a bony canal in close proximity to the tympanic cavity. Other causes include traumatic injuries and exposure to cold.

Facial nerve paralysis is typically unilateral, leading to asymmetric facial deformity: on the affected side, the eye cannot close, the eyebrow cannot be raised, the corner of the mouth and the cheek droop, lip retraction and baring of the teeth are impossible, and the entire mouth is pulled to the opposite side. Attempts to puff out the Cheeks or whistle fail because the lips on the affected side do not seal, allowing air to escape freely through the wide gap. Understandably, under these conditions, speech sound production is significantly impaired, particularly the pronunciation of labial consonants and labialized (rounded) vowels. Impairment of tongue movement can result from Hypoglossal nerve paralysis. Its causes may include trauma, tumor compression, infectious diseases (Influenza, tonsillitis), or Central Nervous system disorders. It is more commonly unilateral; when protruded, the tongue deviates toward the healthy side, and all tongue movements on the healthy side are restricted; the paralyzed half of the tongue gradually decreases in size due to Muscle atrophy from disuse. Speech disorders in this case are mild, manifesting as impaired pronunciation of lingual consonants, and are most often corrected through speech therapy techniques.