Vocal Tract Functions and Skeletal Support

Vocal Tract and Functions

• Articulation: Moving parts of the vocal tract to make different sounds.
• Resonance: How air from the lungs interacts with vocal tract cavities (oral, throat, nose).
• Vocal Tract: Shaped like a backwards "F" in adults. Distance from lips to vocal folds is 17 cm in males, 12 cm in females.
• Oral Cavity: Contains lips, teeth, alveolar ridge, hard palate, soft palate (velum), tongue, and jaw.
• Nasal Cavity: Contains nose, nasal passages (superior, middle, and inferior conchae and meatuses). Function: smelling, air cleaning and moistening.
• Pharyngeal Cavity: From skull base to cricoid cartilage, divided into nasopharynx, oropharynx, and laryngopharynx.
• Velopharyngeal Port: Divides nasopharynx and oropharynx (at base of tongue and epiglottis), and oropharynx and laryngopharynx.

Skeletal Support (Review) and Teeth

• Facial Bones: (Review)
• Teeth: Evolved for chewing (biological) and speech (non-biological).
• Primary Teeth (Deciduous): 20 teeth (erupt ~6 months, replaced by permanent ~6 - 8 years).
• Permanent Teeth: 32 teeth (permanently installed in jaw)
• Incisors: Erupt ~6 months, replace around 6-8 years
• Canines: Erupt ~1.5 years, replace around 9-12 years
• Premolars: Only in permanent teeth, Erupt 10-11
• Molars: 8 in primary teeth, 12 in permanent. First primary molars appear around one year old and replaced by permanent around 6 years old. Second set come in between 11-13. Third molars (wisdom teeth) erupt in early adulthood (or not at all.)
• Occlusion: Edward H. Angle classification (Class I-relatively normal, Class II - abnormal, Class III - abnormal.)

Important Muscles of the Face

• Orbicularis Oris: Oral "sphincter". Origin: Maxilla, mandible, deep skin layers. Insertion: Lip mucosa. Function: Puckering, tight closure of lips. Innervation: CN VII (Facial Nerve)
• Buccinator: Origin: Mandible, maxilla. Insertion: Angle of the mouth. Function: Lip lateral pull, cheek tensioning/pressing against teeth. Innervation: CN VII.
• Levator Labii Superioris: Origin: Frontal process of maxilla, infraorbital region, zygomatic bone. Insertion: Skin of upper lip, side of nose cartilage. Function: Elevates upper lip ,raises mouth angle. Innervation: CN VII.
• Zygomaticus Major: Origin: Zygomatic bone. Insertion: Angle of the mouth. Function: Draws mouth angle up and laterally (smiling). Innervation: CN VII.
• Depressor Labii Inferiorus: Origin: Mandible. Insertion: Lower lip. Function: Pulls lip down and laterally (frowning). Innervation: CN VII.
• Platysma: Broad neck muscle. Origin: Neck fascia, shoulder, chest. Insertion: Mandible, cheek skin, mouth angle, orbicularis oris. Function: Tenses lower face skin, pulls mouth corner down, helps mandible depression. Innervation: CN VII.
• Lips as Articulators: Mobile; orbicularis oris is the primary muscle. Crucial role in lip rounding/protrusion (vowels /u/, consonant /w/) and lip closure (bilabial, labiodental consonants).

Muscles of the Jaw

• Masseter: Origin: zygomatic arch. Insertion: mandible angle and lateral side. Function: Elevates mandible (closes jaw), protrudes jaw. Main chewing muscle. Innervation: CN V (Trigeminal Nerve).
• Temporalis: Origin: temporal bone, Insertion: top of mandible ramus. Function: Elevates mandible (closes jaw), retracts jaw. Main chewing muscle. Innervation: CN V.
• Medial Pterygoid: Origin: Pterygoid plate (sphenoid), maxilla. Insertion: Mandible ramus and angle (inside). Function: Elevates mandible (closes jaw), protrudes mandible. Innervation: CN V.
• Lateral Pterygoid: Origin: Greater wing of sphenoid, lateral pterygoid plate. Insertion: Mandible condyle, temporomandibular joint. Function: Depresses mandible (opens jaw), protrudes mandible, moves mandible laterally. Innervation: CN V.
• Other Jaw Muscles: Anterior belly of digastric, mylohyoid, geniohyoid. Function: Depress jaw (open). Geniohyoid also shortens mouth floor. Innervation: Anterior digastric and mylohyoid - CN V, Geniohyoid - C1/cervical nerve/plexus.
• Jaw as Articulator: Jaw moves, changing oral cavity size; positions lips/tongue; fine jaw movement associated with speech.

Muscles of the Soft Palate and Velopharynx

• Tensor Veli Palatini: Origin: Sphenoid bone, Eustachian tube. Insertion: Palatine aponeurosis. Function: Tenses soft palate, dilates Eustachian tube. Innervation: CN V (Trigeminal N.)
• Levator Veli Palatini: Origin:Temporal bone, Eustachian tube. Insertion: Palatine aponeurosis. Function: Elevates soft palate. Innervation: CN X (Vagus nerve) and CN XI (Accessory Nerve) (Pharyngeal Plexus).
• Musculus Uvulae: Origin: Posterior nasal spine. Insertion: Palatine aponeurosis, uvula mucosa. Function: Shortens/elevates uvula, complete velopharyngeal closure. Innervation: CN X and CN XI (Pharyngeal Plexus).
• Palatoglossus: Forms anterior faucial arch/pillars, Depresses palate sides. Innervation: CN X and CN XI (Pharyngeal Plexus).
• Palatopharyngeus: Forms posterior faucial arch/pillars. Depresses/tenses soft palate, narrows pharynx. Innervation: CN X and CN XI (Pharyngeal Plexus).
• Soft Palate as Articulator: Mobile; crucial for speech and resonance. Velar consonant sounds (/k/, /g/); VP closed for oral sounds, open for nasal sounds. Normal VP closures: coronal, sagittal, circumferential/circular.

Tongue - Intrinsic Muscles

• Tongue: Crucial for speech and swallowing. Landmarks: Superior surface (median sulcus, septum), Inferior surface (lingual frenulum, salivary gland ducts). Divisions: tip, blade, dorsum, root. Muscular hydrostat.
• Intrinsic Muscles: Superior longitudinal, inferior longitudinal, transverse, and vertical; adjust tongue shape/position.
• Superior Longitudinal: Elevates tongue tip, retracts (with inferior longitudinal). Innervation: CN XII.
• Inferior Longitudinal: Pulls tongue tip down, retracts (with superior longitudinal). Innervation: CN XII.
• Transverse Lingual: Narrows tongue. Innervation: CN XII.
• Vertical Lingual: Flattens/broadens tongue. Innervation: CN XII.

Extrinsic Muscles of the Tongue

• Extrinsic Muscles: Connect tongue to surrounding structures (change tongue position).
• Genioglossus: Primary tongue mover. Origin: Mandible midline. Insertion: Tongue tip/dorsum, hyoid bone. Function: Protrudes (anterior fibers), retracts (posterior fibers), cupping. Innervation: CN XII.
• Hyoglossus: Origin: Hyoid bone. Insertion: Tongue sides (posterior). Function: Depresses tongue sides. Innervation: CN XII.
• Palatoglossus: Forms anterior faucial pillar. Origin: Soft palate. Insertion: Tongue sides. Function: Elevates tongue posterior sides. Innervation: CN X and CN XI (Pharyngeal Plexus).
• Styloglossus: Origin: Styloid process. Insertion: Tongue sides. Function: Retracts/pulls tongue superiorly. Innervation: CN XII.
• Tongue as Articulator: Most important articulator; both extrinsic and intrinsic muscles needed for speech.

Muscles of the Pharynx

• Superior, Middle, and Inferior Constrictor Muscles: Narrow pharynx (superior - nasopharynx, middle - oropharynx, inferior - laryngopharynx). Innervation: CN X and CN XI (Pharyngeal Plexus).
• Stylopharyngeus: Origin: Styloid process. Insertion: Thyroid cartilage, lateral pharyngeal walls. Function: Elevates pharynx, widens pharynx, elevates larynx. Innervation: CN IX.
• Pharynx as Articulator: Changes in pharynx diameter/length affect vocal tract resonance.

Swallowing Anatomy and Physiology

• (Review) Swallowing phases (oral, pharyngeal, esophageal) -Bolus -Penetration -Aspiration -Residue -Backflow

• Oral Preliminary Phase -Sensory awareness -Manipulation (solids/liquids)

• Jaw closer/opener muscle actions

• Oral Transport Phase -Initiates at tongue movement -Tongue tip elevation

• Pharyngeal Stage -Triggering (between anterior faucial pillars/tongue base) -Events: Velopharyngeal closure, hyoid/larynx movement, airway closure, UES opening, tongue/pharyngeal wall movement.

• Esophageal Phase -ESophagus Anatomy -Sphincters (UES, LES) -Peristalsis into stomach(8-20 Seconds)

Test your knowledge on the anatomy and functions of the vocal tract and the skeletal structure that supports it. This quiz covers articulation, resonance, and the roles of different cavities and teeth in phonation and mastication. Understand the unique features of the human vocal system along with the facial bones involved.