Articulation L2 - The Oral Cavity Moodle-2.pptx

Oral Cavity The Mouth Biological Functions • Established communication between the digestive and respiratory tracts and the exterior • Initiation of the digestive process Nonbiological Function • Structures of mouth may modify the resonant characteristics of the vocal tract and may also generate spe...

Oral Cavity The Mouth Biological Functions • Established communication between the digestive and respiratory tracts and the exterior • Initiation of the digestive process Nonbiological Function • Structures of mouth may modify the resonant characteristics of the vocal tract and may also generate speech sounds • Lips are mediators of facial expression • Movement of lips and face provide visible secondary cues that facilitate communication • Mouth is the most movable and adjustable cavity in the vocal tract • Structures of mouth associated with articulation include the lips, tongue, teeth, hard palate, soft palate, cheeks, and lower jaw • Faucial pillars, tonsils, velopharyngeal mechanism, muscles of facial expression The Lips (Rima Oris) - Anatomy • Form orifice of mouth and part of external boundary of oral cavity • Covered externally by skin and internally by mucous membrane; between skin & mucous membrane are muscles, glands, fat • Cupid’s bow: well-defined line where skin of lips terminate • Philtrum: vertical groove connecting the tubercle to the septum of the nose • Columella: a vertical ridge the bounds each side of the philtrum • Superior labial frenulum: fold of tissue found on inner surface of upper lip that connects the lip to the alveolar region • Inferior labial frenulum: joins the lower lip with the mandible: weaker than the superior labial frenulum The Cheeks (a.k.a. buccae) • Are continuous with the lips • Composed externally of skin and internally of mucous membrane; between are facial muscles, muscles of mastication, glandular tissue, and a rather prominent subcutaneous pad of fat, at least at first. Glands • Mucin is the primary substance of mucus; maintains the status of the mucous membrane through its emollient (softening) action; allows free movement of the membranes without damaging friction • Saliva – prevents irritation of mucous membranes within the mouth. A rather constant flow of saliva is essential to normal speech production The Teeth • Have both biological and nonbiological functions • Biologically, the teeth are seen to be the precursors of the digestive tract • Nonbiologically, the teeth contribute to the appearance of the face and to normal speech production • Teeth are not vital to sustaining life • Humans have two sets of teeth 1. Deciduous teeth: they form in utero and erupt in infancy and early childhood; they are smaller and whiter than permanent teeth and may become extremely worn in the older child 2. Permanent teeth: erupt at an early age and remain for life (unless affected by disease) Types of Teeth • Four general types of teeth: incisors, cuspids/canines, premolars, molars Incisors - two front teeth (top & bottom) are your central incisors - one lateral incisor is found on either side of the central incisors - suited for biting and shearing Canines (Cuspids, Eye Teeth) - immediately lateral to the lateral incisors (one only) - large teeth with a single pointed crown or cusp - suited for ripping and tearing Types of Teeth Premolars (Bicuspids) - located posterior to the canines - 8 premolars in the permanent dental arch; none in the deciduous arch - suited for crushing & grinding Molars - the largest teeth - 12 in the permanent arch and 8 in the deciduous arch - suited for crushing & grinding Deciduous (Primary) Dental Arch • Deciduous teeth are smaller and fewer in number than permanent teeth • Complete deciduous dental arch contains 20 teeth; 10 in the mandibular arch and 10 in the maxillary arch • Upper and lower jaw each houses 2 central incisors, 2 lateral incisors, 2 canines, and 4 molars • Eruptions begins during the second half of the first year of life and continues until the end of the second year Permanent Dental Arch • There are two groups of permanent teeth: successional permanent teeth: those that replace the deciduous teeth and superadded permanent teeth: those that have no deciduous predecessors • Each jaw has a total of 16 permanent teeth: 4 incisors, 2 canines, 4 bicuspids or premolars, and 6 molars Not Covering These Sections From Your Book • Components of a Tooth • The Development of Teeth Spatial Relationships of the Teeth • The maxillary arch has a slightly larger diameter and is longer than the mandibular arch • Normal relationship results in a maxillary overbite; the upper arch overlaps and confines the lower arch; upper incisors and canines, and to a lesser extent the premolars bite outside of the lower teeth. • Overjet is the amount by which the upper incisors lie anterior to the lower incisors. • Diastema or spaces between the teeth may develop during the process of eruption of the permanent teeth; this is normal and is usually self correcting. Occlusion • The alignment of the teeth in the upper and lower arches, the relationship of the upper and lower arches to each other, and the positioning of individual teeth • 3 classes of occlusion describe the relationship of the upper & lower jaw Class I (normal) occlusion: cusps of the first mandibular molar resting ahead and inside of the corresponding cusps of the maxillary teeth; provides a normal facial profile Class I malocclusion: first molar relationship is intact, but an anomaly exists in the anterior region of the arch Occlusion Class II malocclusion: cusps of the first mandibular molars are behind and inside the opposing molars of the maxillary arch; most common malocclusion; found in about 45% of the population; results in an increased overjet, the appearance of a receding chin, and a decrease in the lower facial height Class III malocclusion: cusps of first mandibular molar interdigitate a tooth (or more) ahead of the opposing maxillary incisors; gives the appearance of a prognathic jaw & an increase in facial height Open and Closed Bites • Open bite: anterior teeth are unable to approximate and a persistent space exists between them – caused by infraversion of the anterior teeth (the anterior teeth fail to erupt sufficiently) or by supraversion of the posterior teeth (the posterior teeth have erupted past the normal line of occlusion) Open and Closed Bites • Closed bite: the posterior teeth fail to meet – infraversion of the posterior teeth or a supraversion of the anterior teeth • An open bite may contribute to deficits in speech production Take Care of Your Teeth! The Palate Contribution to Speech: • serves as a point of articulation • modifies the degree of coupling between the nasopharynx and the remainder of the vocal tract • Bony hard palate and muscular soft palate – velum Hard Palate • Anterior ¾ formed by medial projections of the palatine processes of the maxillae; • Posterior ¼ formed by the palatine bones, continue back at midline to form the posterior nasal spine • Covered by a mucous membrane; posterior slope of the alveolar arch forms wrinkles called rugae which probably facilitate linguapalatal articulation rugae The Palatal Arch - The hard palate is thick at its anterior and lateral margins and becomes progressively thinner toward the midline; this results in the palate being arched; the extent of the vault (arch) varies considerably from person to person - The height of the palatal vault has a direct bearing on the acoustic properties of the oral cavity and may well contribute to individual voice characteristics Soft Palate (Velum) - Attached to the posterior free border of the palatine bones by means of a palatal aponeurosis (skeleton of velum) - Directed posteriorly - When relaxed hangs curtain-like into the oropharynx – including the extension, the uvula, is visible. - Five muscles are responsible for the mobility of the soft palate which can be elevated, lowered, or tensed - Modifies the general configuration and consequently the resonant characteristics of the vocal tract - Raised for most speech and for swallowing; lowered for nasal sounds & normal breathing Muscles  You should learn about the following muscles in detail (origin, course, insertion, and function).  For the remaining muscles of articulation (i.e., any muscle not on this list), you should know just the function of the muscle group. • orbicularis oris, buccinator, superior longitudinal, inferior longitudinal, transverse, vertical, genioglossus, styloglossus, palatoglossus, hyoglossus, masseter, temporalis, tensor veli palatini, levator veli palatini, glossopalatinus, palatopharyngeus Tensor Veli Palatini Origin: sphenoid bone and the Eustachian tube* Course: down and medial Insertion: posterior portion of palatine bone and soft palate Innervation: cranial nerve V (trigeminal) Function: tense and lower the soft palate; dilates and opens the Eustachian tube Levator Veli Palatini • Forms the bulk of the soft palate Origin: petrous portion of temporal bone and the Eustachian tube Course: downward, medial, & forward Insertion: soft palate Innervation: cranial nerve X (vagus) Function: elevates the soft palate; closes off the velopharyngeal port Musculus Uvulae Origin: nasal spines of the palatine bone and palatine aponeurosis Course: posteriorly Insertion: uvula of velum Innervation: cranial nerves X (vagus), XI (spinal accessory) Function: shortens and elevates the soft palate; strengthens seal of velopharyngeal port Palatoglossus Muscle (Glossopalatinus Muscle) Origin: anterior surface of velum Course: downward and lateral Insertion: sides of the tongue Innervation: cranial nerves X (vagus), XI (spinal accessory) Function: lowers soft palate Palatopharyngeus Muscle (Pharyngopalatine Muscle) Origin: velum, pterygoid hamulus, Eustachian tube Course: down Insertion: superior cornua of thyroid; lateral wall of pharynx Innervation: cranial nerves X (vagus), XI (spinal accessory) Function: lowers velum; pulls velum back Superior Pharyngeal Constrictor • Assists in creating greater seal of velopharyngeal port by pulling lateral walls inward • Will discuss with pharyngeal muscles