RESPIRATORY SYSTEM

• Philtrum - the groove in the lip and middle of the nose separating the nostrils.
• Philtrum - deep in the carnivores and small ruminants; shallow or absent in pig, ox, and horse.
• Nasal Diverticulum is also called False Nostril.
• Nasal Diverticulum - the dorsal passage through the horse's nostrils into a blind cutaneous pouch.
• When "tubing" a horse, a thumb placed in the diverticulum will aid in directing the tube into the ventral nasal meatus.
• Rostral Bone - the bone in the nose of a pig to help it "root".
• Lateral ventricle of the larynx - present in the horse, pig, and dog; absent in cat and ruminant.
• Respiratory System - the connected structures from the nostrils and oral cavity to and including the lungs.
• Nasal cavity - the facial portion of the respiratory tract extending from the nostrils to the caudal nares.
• Laryngeal cavity - the space enclosed by the laryngeal cartilages, muscles, ligaments, and mucous membrane.
• Tracheal bronchus - the bronchus in ruminants and pigs arising cranial to the tracheal bifurcation to the supply the right lung's cranial lobe.
• Generalized pattern of lobes (Lungs) - two lobes on the left (cranial and caudal) and four on the right (cranial, caudal, middle, and accessory).
• Carnivores, pig, and ruminants - have the generalized pattern of lobes (lungs).
• Ruminants - both right and left cranial lobes of lungs are divided into cranial and caudal parts.
• Ruminants - have distinct connective tissue septa in the lung tissue.
• Horse - missing the right middle lobe, thus only has three lobes on the right, five total. The lobes are not divided by distinct fissures.