Overview
This lecture covers the key anatomical structures and functions of the upper respiratory system using a half-head model, emphasizing airflow pathways, tissue types, and protective mechanisms.
Nasal Cavity Structures
- The external nares are the nostril openings where air enters the nasal cavity.
- The vestibule is the initial region inside the nose, lined with vibrissae (nose hairs) to filter large particles.
- The nasal cavity is lined with pseudostratified ciliated columnar epithelium to filter, moisten, and warm incoming air.
- Superior, middle, and inferior nasal conchae increase surface area and create turbulence to enhance air humidification and filtration.
- Meatuses (superior, middle, inferior) are passageways below each concha that direct airflow.
- The internal nares are the posterior openings to the nasal cavity.
Associated Sinuses and Tonsils
- Frontal, ethmoid, and sphenoid sinuses are air-filled spaces that lighten the skull and affect voice resonance.
- The pharyngotympanic (auditory/Eustachian) tube connects the nasopharynx to the middle ear for pressure equalization.
- Tubal, pharyngeal (adenoids), palatine, and lingual tonsils are lymphatic tissues that help defend against pathogens.
Palate and Oral Cavity
- The hard palate (bone) forms the floor of the nasal cavity; the soft palate (muscle) extends posteriorly.
- The uvula is the soft palate extension that blocks the nasopharynx during swallowing.
- The palatoglossal and palatopharyngeal arches border the oral cavity and house the palatine tonsils.
Pharynx Regions and Tissue Types
- The pharynx is divided into the nasopharynx (air only, pseudostratified ciliated columnar epithelium), oropharynx, and laryngopharynx (both stratified squamous epithelium for protection).
- The oropharynx and laryngopharynx contact food, air, and fluids, requiring abrasion resistance.
Larynx and Voice Production
- The larynx directs air into the trachea and food into the esophagus via the epiglottis.
- The epiglottis (elastic cartilage) closes over the larynx during swallowing.
- True vocal cords (vocal folds) vibrate to produce sound; false vocal cords (vestibular folds) do not.
- The glottis is the space between the true vocal cords responsible for phonation.
Cartilages of the Larynx
- The hyoid bone anchors the laryngeal structures.
- The thyroid cartilage forms the "Adam's apple," more prominent in males.
- The cricoid cartilage fully encircles the larynx below the thyroid cartilage.
- The arytenoid cartilages adjust tension on the vocal cords for sound modulation.
Key Terms & Definitions
- Nares (External/Internal) — Openings at the entrance and exit of the nasal cavity.
- Vibrissae — Nose hairs in the vestibule that filter particles.
- Conchae — Curved bones in the nasal cavity increasing surface area.
- Meatus — Air passageways underneath each nasal concha.
- Pharynx — Throat region divided into nasopharynx, oropharynx, and laryngopharynx.
- Epiglottis — Flap of elastic cartilage preventing food from entering the larynx.
- Glottis — Opening between the true vocal cords.
- True Vocal Cords — Ligaments that vibrate to produce sound.
- Cricoid Cartilage — Ring-shaped cartilage at the base of the larynx.
- Arytenoid Cartilage — Cartilage that adjusts vocal cord tension.
Action Items / Next Steps
- Review anatomical diagrams of the respiratory system, focusing on nasal cavity, pharynx, and larynx structures.
- Learn to identify and label the different types of tonsils and cartilages on a model.
- Prepare for a quiz on the function and tissue types of each airway region.