Untitled Quiz

Respiratory System

• The respiratory system has four main functions: gas exchange, improving and regulating air, olfaction, and voice production.
• The respiratory system is composed of three main parts: the air conducting part, the respiratory part, and the pumping apparatus.
• The air conducting part includes the nose (nostrils and nasal cavity), nasopharynx, larynx, and trachea, as well as the conducting portion of the bronchial tree.
• The respiratory part includes the respiratory portion of the bronchial tree and alveoli.
• The pumping apparatus includes the two pleural sacs, the skeleton and muscles of the thorax, and the diaphragm.

Nose

• The nose in domestic animals typically does not project as far from the face as in humans, but in dogs and pigs, it protrudes more.
• The nostrils are two openings at the apex of the nose that lead to the nasal cavity.
• The nasal septum is a partition between the nostrils, dividing the nasal cavity into right and left halves. Its rostral portion is cartilaginous, while the caudal portion is osseous.
• The nasal wall consists of skin externally, a supporting layer (cartilage rostrally, bone caudally), and mucous membrane internally.
• The bones supporting the nose include nasal, maxilla, incisive, frontal, lacrimal, zygomatic, and the prependicular part of the palatine bone.

Nasal Cartilages

• The most rostral part of the nasal cavity and nostrils are supported by cartilages.
• These include the dorsal and ventral lateral nasal cartilages.
• In carnivores, pigs, and ruminants, the two cartilages come together laterally to the nostril.
• In horses, the dorsal cartilage does not project far laterally, and the ventral cartilage may be absent.
• Other cartilages include lateral accessory, medial accessory, and alar cartilages.

Nostrils

• Nostrils are the external openings of the nasal cavity.
• They have dorsal and ventral commissures, and medial and lateral borders.
• Nostril shape, size, and position vary among domestic animals.
• The area surrounding the nostrils is comprised of modified skin that differs based on the species.

Nasal Cavity

• The nasal cavity is divided by the nasal septum into right and left halves.
• It opens externally via the nostrils (rostral nares) and communicates caudoventrally with the nasopharynx via the choanae (caudal nares).
• It also communicates with paranasal sinuses.
• The nasal cavity has three regions: the nasal vestibule (rostral part), the nasal cavity proper (middle and largest part), and the nasal fundus (caudal).
• The nasal cavity is lined with mucosal tissue, with the rostral section containing a cutaneous membrane, and the caudal section containing olfactory mucosa.

Nasal Meatuses

• Nasal meatuses are passages formed by nasal conchae, dividing the nasal cavity into smaller sections.
• Types include: dorsal nasal meatuses, middle nasal meatuses, ventral nasal meatuses, and common nasal meatuses.
• Each meatus varies by species; location and function differ based on specific functions (olfactory or respiratory) and species.
• These meatuses are critical for regulating airflow, distributing air, conditioning air (temperature and humidity), and providing additional surface area for mucous membrane.

Paranasal Sinuses

• These are air-filled spaces in the skull, lying between external and internal bone laminae.
• They are lined with respiratory mucosa and communicate with the nasal cavity, varying in number, size, and shape based on species.
• Functions include protecting the orbits and cranial cavities, enlarging the skull for muscle attachment, increasing resonance of sound, and lightening the skull.
• Types include frontal, maxillary, palatine, sphenoid, and lacrimal sinuses.

Maxillary Sinus

• It exists in all domestic animals and opens to the middle nasal meatus through the nasomaxillary aperture
• Carnivores: Its anatomical structure deviates from true sinuses because it does not lie between the internal and external bone sheets; it's called a maxillary recess.
• Pigs and cattle: Maxillary sinus's shape and position vary significantly; it has distinct rostral and caudal parts; both open to the middle nasal meatus through a wide nasomaxillary opening.
• Ruminants: The sinuses communicate with the palatine sinus across the infraorbital canal
• Horses: maxillary sinus has a rostral and caudal component separated by a septum; the caudal part connects with the sphenopalatine sinus; the rostral part communicates via a connection to the middle nasal meatus

Sphenoid Sinus

• This generally small sinus is absent (or non-existent) in most domestic mammals, including dogs and small ruminants. However, it is larger in pigs.
• Its location and position influence its potential for affecting vision since it is near the optic nerve.

Palatine Sinus

• The palatine sinus is present in ruminants but not in carnivores or pigs.
• Its structure contains an incomplete bony roof and is separated from the nasal cavity by a layer of mucosa.
• In horses, it communicates across the infraorbital canal with the maxillary sinus
• The equine sinus communicates through a passage to the caudal maxillary sinus.

Lacrimal Sinus

• The lacrimal sinus is typically absent in carnivores and horses
• Its function involves connecting the structures of the lacrimal and zygomatic structure with the middle nasal meatus
• Pigs and small ruminants: the lacrimal sinus typically communicates with the ethmoid meatuses.
• In cattle (oxen): The lacrimal sinus communicates with the middle nasal meatus through the maxillary sinus.