ASUNCION, Racela Jian 1SLPACABANTING, Mary AntoinetteCABILI, Juan MarloCORPUS, Patricia AlyrraCRUZ, Allainne NicoleFLORES, Alyson DeniseGOROSPE, MynielNANIONG, Dianne MarieSALCEDO, Jannelle ErickaIntroductionThe Resonatory System is the portion of the vocal tract, wherein the acoustical product of the vocal fold vibration resonates.
It includes the nasal cavity, soft palate, and portions of the anatomically-defined respiratory and digestive systems. (Seikel, King, & Drumright, 2010). The anatomy and physiology of the resonating cavities that will be discussed in this paper are the pharyngeal cavity, nasal cavity, and, oral cavity. II. AnatomyThe pharyngeal cavity is a funnel-shaped tube around 13 centimeters (5 inches) long that stars at the internal nares and extends to the level of the cricoid cartilage, the most inferior cartilage of the larynx.
Aside from that, it lies just posterior to the nasal and oral cavities, superior to the larynx, and just anterior to the cervical vertebrae. Its wall is composed of skeletal muscles and is lined with a mucous membrane.The pharynx is divided into three anatomical regions: the nasopharynx, oropharynx, and the laryngopharynx. The muscles of the entire pharynx are arranged in two layers, an outer circular layer and an inner longitudinal layer.The Nasopharynx is the superior portion of the pharynx which lies posteriorly to the nasal cavity and extends to the soft palate. The soft palate forms the posterior portion of the roof of the mouth, is an arch-shaped muscular partition between the nasopharynx and oropharynx that is lined by mucous membrane. The soft palate has five openings in its wall: two internal nares, two openings that lead into the eustachian tubes, and the opening into the oropharynx.
The posterior wall also contains the pharyngeal tonsil or adenoid.The Oropharynx is the intermediate portion of the pharynx which lies posterior to the oral cavity and extends from the soft palate inferiorly to the level of the hyoid bone. It has only one opening into it, the fauces – the opening from the mouth. The inferior portion of the pharynx, the Laryngopharynx or hypopharynx, begins at the level of the hyoid bone.
At its inferior end, it opens into the oesophagus (food tube) posteriorly and the larynx (voice box) anteriorly. Like the oropharynx, the laryngopharynx is lined by nonkeratinized stratified squamous epithelium.The nasal cavity stretches out from the external entryway, nostrils, pharynx, and continues on to the rest of the respiratory system which may be seen at Figure 1 below. The anterior one third of the nasal cavity is lined by stratified- squamous epithelial cells. The posterior two-third is lined by pseudostratified columnar ciliated epithelium. It contains the goblet cells and is above the basement membrane.The nasal submucosa is below the basement membrane. It is made up of glands, which produces mucus, nerves and blood vessels.
Fig 1. Oral, Nasal, and Pharyngeal CavitiesThe entire mucosa is highly concentrated with blood vessels. It also contains large venous-like spaces that have a vein-like appearance that swells and congests due to allergies or infections.
The nasal septum is a cartilage that divides and forms the nostrils. The nostrils are divided into three parts: roof, walls, and floor. The nasal cavity is divided into the nasal vestibule, respiratory section, and olfactory section. The nasal vestibule is an enlarged region located at the nasal entryway. The respiratory section of the nasal cavity serves as the pathway that enables air to travel into the respiratory system.
Every nostril contains four conchae or protrusions that are also called as turbinate bones or lobes that are concealed by the nasal mucosa. Situated under the are meatuses that connect to the paranasal sinuses. The olfactory section of the nasal cavity is where the olfactory receptors are situated. The structure, Bowman’s Glands, secretes mucus and yellow pigment. The secretions break down odous so that the olfactory system will be able to identify the smell. The surrounding structures of the nasal cavity are the Nasolacrimal ducts, Para-nasal sinuses, and, the oral cavity.
The Nasolacrimal ducts are the ducts that connects the lacrimal ducts, commonly known as tear-ducts, in the eye to the nasal cavity. The nasal cavity is surrounded by rings of para-nasal sinuses. These sinuses develops as outgrowths in the nasal cavity.
The mucosa of these sinuses connects to the Nasal Mucosa. The Nasal Mucosa lines the whole nasal cavity. It is also known as Respiratory Mucosa. It starts from the nostrils up to the pharynx. The external skin of the nose attaches to the nasal mucosa in the nasal vestibule. The oral cavity extends from the oral opening, in front to the faucial pillars. The oral opening is the exit for all orally emitted phonemes (all except nasals).
It lies anteriorly to the oropharynx. It is separated with oropharynx by the circumvallate papillae. The opening of the mouth is surrounded by the lips. The lips are anchored to the adjacent gingiva by the labial frenulum. The oral cavity can be divided into two regions: the vestibule and the oral cavity proper.
The vestibule is the space between the lips, cheeks and the teeth. The oral cavity proper is the region medial to the teeth. The oral cavity is lined with moist epithelium. The boundaries of the oral cavity are the following: laterally by the the teeth and alveolar ridge of the maxillae, superiorly by the hard palate, posteriorly by the anterior tonsillar pillars, and inferiorly by the mylohyoid muscle. The tongue occupies majority of the lower mouth.
Aside from that, the oral cavity structures are mostly under voluntary control. The buccal cavity is lateral to the oral cavity and has a role in oral resonance. It is the space between the posterior teeth and the cheeks. Specifically, It is bounded laterally by the cheeks, anteriorly by the lips, posteriorly by the third molar and medially by teeth.
One example of its role in resonance is the production of high-pressure consonant sounds when the mandible is depressed. In addition, this cavity is also the cause of misarticulation; thereby, distorting the sound /s/.Fig 2. The Anatomy of the Oral Cavity Image from Pediatric Dermatology (Fourth Edition) by Cohen, Bernard, 2013As seen in the figure above, the oral cavity has many parts.
With this, the following are the parts of the oral cavity and its description:The hard palate is the hard roof of the mouth. The rugae are the prominent ridges or crease running laterally. It aids mainly in the formation of bolus during mastication and aids in deglutition as well. The median raphe divides the hard palate into two halves. In addition, the median raphe runs across the palate , from the palatine uvula to the incisive papilla. The juncture between the hard and soft palate and the soft portion is called the Soft Palate or velum.
The end point of the Soft Palate is the uvula.In addition, the velum is the movable muscle separating the oral cavity to the nasal cavity. The uvula is the fleshy extension of the velum or soft palate.It projects downward from the middle of the soft palate. The anterior and posterior faucial pillars are prominent bands of tissue on either side of the soft palate. The palatine tonsils is situated between the anterior and posterior faucial pillars. In addition, it also invades the lateral undersurface of the soft palate.The oral mucosa is the moist lining of the oral cavity.
The lips are the fleshy muscular folds that is covered by the skin, externally. Internally, the lips is covered by mucosa. The lips are not highly-keratinized; thus, giving a reddish-pink appearance. The cheeks are musculare structures. It is covered interiorly by moistnon-keratinized stratified squamous epithelium.
The tongue occupies the floor of the oral cavity. There are two types of muscles associated with the tongue. The intrinsic muscles and the extrinsic muscles.
The intrinsic muscles are the muscles within the tongue. The extrinsic muscles are the muscles outside the tongue.The teeth is situated in the alveoli along the alveolar ridge of both mandible and maxilla. The alveolar processes are covered by the gingiva, commonly known as the gums. To have a clearer visualization on what the oral cavity looks like, one may palpate it. This may be done by the following steps. Ask the patient to open his/her mouth, then one may us their non-dominant hand to hold the flashlight as they palpate the oral cavity with their dominant hand.
III. PhysiologyBefore discussing the physiology of the cavities, it is necessary to discuss this theory to have a deeper understanding of resonation. Based on the Source-Filter Theory, speech production is seen to have two stages, namely the generation of sound and filtering of the resonators. Generally, voicing is generated by the vocal folds and goes through the vocal tract where it is shaped into speech sounds.
The changes in shape of the articulators such as the tongue, mandible, and soft palate affect the resonance characteristics of the vocal tract, and determine what vowel sound is being produced. The changes of sound produced by the resonators depend on how the articulators are shaped through its length and volume, therefore as the volume of the resonator decreases, the frequency increases. A diagram of the theory can be seen below. Fig 3. The Source-Filter TheoryIn addition to this, the vocal tract acts as a filter as seen on Figure 3 which allows a certain frequency to pass through while rejecting other frequencies. This can be parallelized to how a coffee filter allows water to pass through it while the coffee grounds are blocked by the filter. This means that the filter attenuates at certain frequencies (Mannell, n.
d.). The resonant frequencies govern the perception of vowels and not the vocal tract itself only. An example would be the words who and he in which both of these words do not cause the vocal folds to vibrate, but instead by the turbulence of the whispered production due to the oral cavity filter getting excited, and allowing the listener to detect the difference between the two words. The Source-Filter Theory also extends to other phonemes, however unlike the vowels, which source has voicing, consonants have varying sources, such as fricative turbulence, plosive stops, voicing, or a combination of all.
Overall, in all cases, in order to meet one’s acoustic needs, a noise source that passes through a configured filter of the oral cavity is needed.The Pharyngeal Cavity extends from the top of the trachea and esophagus, past the epiglottis and the root of the tongue, to the region at the rear of the soft palate. This shape and volume of this chamber may also be modified through the constrictive action of the muscles enclosing the pharynx, the movement of the back of the tongue, the position of the soft palate when raised, and the raising of the larynx.Moreover, this serves as the passageway for air and food and is very important in the process of swallowing. It also houses the tonsils, which gives an immunological response against foreign invaders. Lastly, it acts as the conducting zone of the respiratory system, which in a way, supplies a resonance chamber for speech sounds.
The Olfactory System functions in processing information about smell. This consists of the para-nasal sinuses, wherein it resonate speech and produce mucus that enters the nasal passageway. Moreover, moisture inherent in the nasal mucosal with the vascular supply of nasal tissue, acts as a humidifier, warms the air as it enters the passageway. In other words, it allows air to enter through respiration. The oral cavity always undergoes changes during speaking. Aside from the regulation of the intake of substances, the structures in the oral cavity is responsible in the modulation of air expelled from the lungs. In addition, this voluntary control is responsible in controlling the amount of airflow exhaled, and shaping the noise generated by airflow into speech. The intrinsic muscles of the tongue are responsible for altering the tongue’s shape and size.
It is necessary for swallowing and speaking. The Lingual Frenulum aids in limiting the movement of the tongue posteriorly. It also facilitates normal speech. Generally, the length of the vocal tract of an infant is shorter than an adult’s.
The vocal tract length is approximately 6 to 8 centimeters at birth while for an adult, it is 15 to 18 centimeters. The oral cavity matures when the is child between 7 and 18 years old. During development, the infant’s nasopharynx enlarges. It becomes more sharply angled relative to the oropharynx. The pharyngeal cavity, oral cavity and oropharyngeal space grow.
Descension of the tongue occurs as well. These changes that occur during development affect both swallowing and speech function. Moreover, the vocal tract length is the main determinant of the first formant in vowel production, making it an extremely important structure (Seikel, King, ; Drumright, 2010).