Salivary duct and parotid salivary gland: Rostral to the masseter muscle several structures can be found coursing from the medial aspect of the mandible to the lateral side. Some species and individual variation does exist in the number of structures found in this location. In the horse and large ruminant three can be found; facial artery, facial vein and parotid salivary duct. In the small ruminant, only the facial vein is reliably found in this location, however many individuals will also have the parotid duct.
To reduce risk of damage to the structures find the salivary duct, facial artery and vein at the rostro-ventral border of the masseter muscle. Carefully separate the vessels from the connective tissues moving caudally towards the parotid salivary gland.
Reflect the levator labia superiors muscle to find the infraorbital nerve exiting from the infraorbital foramen. The relationship of the levator labia superioris muscle to the infraorbital nerve is of clinical relevance, particularly in the horse. When performing regional anesthesia of the infraorbital nerve the thick bellied levator labia superiors muscle must be reflected so a needle can be passed through the infraorbital foramen and into the canal to gain access to the nerve.