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==Introduction==

==Introduction==

The Paranasal Sinuses are ventilated spaces connected to the [[Nasal cavity - Anatomy & Physiology|nasal cavity]].

The Paranasal Sinuses are ventilated spaces connected to the [[Nasal Cavity - Anatomy & Physiology|nasal cavity]].

They develop as blind ending pouches between the lamina of the [[Skull and Facial Muscles - Anatomy & Physiology#Bones of the Skull|bones of the skull]].

They develop as blind ending pouches between the lamina of the [[Skull and Facial Muscles - Anatomy & Physiology#Bones of the Skull|bones of the skull]].

*The paranasal sinuses are a series of cavities arranged one after another.

*The paranasal sinuses are a series of cavities arranged one after another.

*All species have ''Frontal'' and ''Maxillary'' systems

*All species have ''Frontal'' and ''Maxillary'' systems

**''Frontal'': consists of space(s) within the bones between the cranial cavity and the [[Nasal cavity - Anatomy & Physiology|nasal cavity]].

**''Frontal'': consists of space(s) within the bones between the cranial cavity and the [[Nasal Cavity - Anatomy & Physiology|nasal cavity]].

**''Maxillary'': this is the largest sinus, and consists of the space within the caudolateral part of the upper jaw, above the caudal cheek [[:Category:Teeth - Anatomy & Physiology|teeth]]. This increases with age due to wearing and ventral relocation of the [[:Category:Teeth - Anatomy & Physiology|teeth]].

**''Maxillary'': this is the largest sinus, and consists of the space within the caudolateral part of the upper jaw, above the caudal cheek [[:Category:Teeth - Anatomy & Physiology|teeth]]. This increases with age due to wearing and ventral relocation of the [[:Category:Teeth - Anatomy & Physiology|teeth]].

==Species Differences==

==Species Differences==

*In the '''Dog''' the sinus system is generally poorly developed. The Maxillary sinus is a cavity which freely communicates with the nasal cavity, and is known as the '''Maxillary Recess'''. The Frontal sinus has 3 chambers which drain separately into the [[Nasal cavity - Anatomy & Physiology|nasal cavity]].

*In the '''Dog''' the sinus system is generally poorly developed. The Maxillary sinus is a cavity which freely communicates with the nasal cavity, and is known as the '''Maxillary Recess'''. The Frontal sinus has 3 chambers which drain separately into the [[Nasal Cavity - Anatomy & Physiology|nasal cavity]].

*In the '''Horse''' the Maxillary sinus has caudal and rostral parts which together occupy a large part of the upper jaw. In addition, the horse has ''Sphenopalatine'' and ''Ethmoidal'' sinuses which are of less clinical importance than the ''Frontal, Caudal Maxillary'' and ''Rostral Maxillary Sinuses'' on each side of the [[Skull and Facial Muscles - Anatomy & Physiology#Bones of the Skull|skull]].

*In the '''Horse''' the Maxillary sinus has caudal and rostral parts which together occupy a large part of the upper jaw. In addition, the horse has ''Sphenopalatine'' and ''Ethmoidal'' sinuses which are of less clinical importance than the ''Frontal, Caudal Maxillary'' and ''Rostral Maxillary Sinuses'' on each side of the [[Skull and Facial Muscles - Anatomy & Physiology#Bones of the Skull|skull]].

*'''Cattle''' do not have a fully developed sinus system until the age of 7, by which time it is an extremely complex system.  

*'''Cattle''' do not have a fully developed sinus system until the age of 7, by which time it is an extremely complex system.