Human Anatomy: The Upper Airway

Study Notes

Consists of the nose, oral cavity, pharynx, and larynx
Functions include:
- Air conduction
- Air humidification and cooling
- Prevention of foreign material entry
- Speech and smell involvement

Composed of lateral, greater alar, lesser alar, septal cartilage, and fibrous fatty tissue

The nasal septum separates the nasal cavity into two equal parts
- Posteriorly formed by the perpendicular plate of the ethmoid bone and vomer
- Anteriorly formed by the septal cartilage
The roof is formed by:
- Nasal bones
- Frontal process of the maxilla
- Cribriform plate of the ethmoid bone
The floor is formed by:
- Palatine process of the maxilla and palatine bones
Posterior section of the nasal cavity floor is formed by the superior portion of the soft palate (collagen)
Air enters through the:
- Septal cartilage and alae nasi (nares or nostrils)

Contains a vestibule (outer portion between teeth, gums, and lips) and a larger section behind the teeth and gums extending to the oropharynx
The tongue is located on the floor of the oral cavity and is composed of:
- Skeletal muscles and fibers
  - Intrinsic muscle fibers: change tongue shape, aid in speech and swallowing
  - Extrinsic muscle fibers: change tongue position (protrude, side to side, etc.)
- Lingual frenulum: secures the tongue to the floor of the mouth
- Papillae: house taste buds
The roof of the mouth is formed by a hard plate and soft plate:
- Hard plate: formed by the palatine process of the maxilla and palatine bones
- Soft palate: a flexible, fleshy structure of densely packed collagen fibers that closes the opening between the nasal and oropharynx
  - Elevated by the levator veli palatini muscle
  - Drawn forward and down by the palatopharyngeal muscles
The oral cavity is lined with stratified squamous epithelium
Palatine arches:
- Palatopharyngeal arch
- Palatoglossal arch
The palatine tonsil is located on each side of the oral cavity between the palatine arches

Also known as the voice box
Located between the base of the tongue and the trachea
Functions as a passageway for air from the pharynx to the trachea, provides protection, generates sound
Contains nine cartilages:
- Single: thyroid, cricoid, epiglottis
- Paired: arytenoid, corniculate, cuneiform
Held together by ligaments and intrinsic and extrinsic muscles
The epiglottis is spoon-shaped and covers the entrance of the larynx to prevent food aspiration
Connected to the base of the tongue via the vallecula
The cricoid has a narrow pressure point in adults
Arytenoid, corniculate, and cuneiform cartilages aid in the movement of vocal cords
Membranes:
- Thyrohyoid: roof, narrowest part
- Cricothyroid: floor of the larynx
Vocal folds (formed by mucous membrane):
- True vocal folds: involved in sound production
- False vocal folds: not involved in sound production