Upper Respiratory Tract Flashcards
Components of URT
•Nasal cavity and paranasal sinuses
•Mouth
•Pharynx - now
•Larynx - next lecture
•Trachea and bronchi before they enter the lung
Function of URT
The obvious function of these passages is to conduct air to and from the
lungs. However, they also serve other functions. Most important of these
are
1. Modification of inspired air
2. Defence of the body against harmful substances
3. Olfaction and Gustation
4. Vocalisation
How does it modify air
3 ways:
- Temperature- adjust to body weight.
- Humidification- alveolar air is nearly 100% saturated with water vapour
- Removal of particulate matter-either be sneezing or by the mycociliairy escalator ONLY PARTICLES UNDER 3um ever reach the aklveoli
Defence of the body against harmful substances
-filtration
-coughing/sneezing
-reflex closure of the glottis
-continuous movement of mucous which also contains lysozyme which may destroy some bacteria
-lymphoid tissue
Olfaction
Olfaction: air is drawn to the caudal part of the nasal cavity, mucosa has lots of olfactory cells and their axons pass through the cribriform plate into the olfactory bulb of the brain
Gustation
Gustation: taste rostral 2/3 chords tympani of facial nerve, caudal 1/3 via glossopharyngeal SVA neuron
What is the demarcation of the 1/3 of the tongue
vallate papillae
Small raised soft tissue midline of the palatine
Incisive papilla, underneath palatine fissure that connect the oral and nasal cavities
Arising causally from the duct and lying in the floor of the nasal cavity is?
The vomeronasal organ
What is thee vomeronasal organ or Jacobson’s organ
-small paired organs associated with detection of pheromones and lie embedded in hard palate
-receives nerve supply from the olfactory nerve and the maxillary branch
The ducts of the vomeronasal organ communicates with what? Expect in which animal?
Oral and nasal expectancy in horses where it communicates with nasal cavity only
Vocalisation
-caused by vibration of the vocal cords
Which animals can’t breathe through their mouths and why?
Horse, domestic cats, lagomorphs (bunnies and hares) and rodents can’t because they have a very long hard palate
Modification of URT during exercise
- Dilation of the external nares
- Vasoconstriction of the nasal mucosa. The nasal mucosa is very vascular
so vasoconstriction dilates the common and ventral meati. - Dilation of the glottis (the airway within the larynx). This point will be discussed further in the larynx lecture.
How do horses dilate their nares
Alar cartilage pulled medially by DILATOR NARIS LABIALIS
Which bones near the alar fold
-lamina of alar cartilage
-Cornu of alar cartilage
Muscles of facial expression and inervation
Caninus, levator nasolabialis, dilator naris apicalis, lateralis nasi
-innervated by facial nerves
What is the pharynx
Chamber that is the continuation of oral and nasal cavities
What is the hard palate
Bony shelf made up of incisive maxilla and palatine bones. Divides nasal cavity from oral cavity
What is the soft palate
caudal continuation of the hard palate. A soft tissue
structure consisting of muscles, small salivary glands, and covered by mucosa
(respiratory mucosa on the dorsal surface, and oral mucosa on the ventral
surface).
The larynx
Gateway to the trachea made up of 4 cartilages-epiglottis, arytenoids, thyroid and cricoid
3 parts of the pharynx
-nasopharynx: a space above the soft palate
-osopharynx: a space below the soft palate
-laryngopharynx: a space above the larynx
Muscles of the pharynx
CONSTRICTION
-Rostral: hyopharyngeus running from the thyrohyoid and ceratohyoid bones to the wall of the pharynx
• Middle; thyropharyngeus, running from the thyroid cartilage to the wall of the pharynx
• Caudal cricopharyngeus, running from the cricoid cartilage to the wall of the pharynx
SHORTENERS OF THE PHARYNX
PALATOPHARYNGEUS-running from the soft palate to the dorsal wall of the pharynx (also constricts the pharynx and helps to form the palatopharyngeal arch which forms a cuff around the larynx during nose breathing in horses
PTERGOPHARYNGEUS-running from the pterygoid process to the dorsal wall of the pharynx
DILATOR OF THE PHARYNX
-widens the pharynx during swallowing to accommodate the bolus
STYLOPHARYNGEUS
Muscles of soft palate
-tensor veli palatini
-levator veli palatini
-palatinus
Innervation soft palate
Tensor veli palatini_mandibular trigeminal
Levator palatini and palatinus glossopharyngeal et vagus nerve complex
Muscles pharynx
All innervated by the glossopharyngeal et vagus nerve complex (SVE).
Nerve supply to the mucosa of the soft palate and pharynx
• General sensation and taste from the mucosa of the pharynx and soft
palate glossopharyngeal et vagus nerve complex (SVA/AA).
• Glands of the mucosa of the pharynx and soft palate are innervated by
parasympathetic motor fibres from facial VII, glossopharyngeal et vagus
nerve complex .
• Sympathetic supply comes from the cranial cervical ganglion.
