Paranasal Sinuses - Anatomy & Physiology

()Map CARDIORESPIRATORY SYSTEM (Map)

Introduction

The Paranasal Sinuses are ventilated spaces connected to the nasal cavity. They develop as blind ending pouches between the lamina of the bones of the skull.

Structure

• The paranasal sinuses are a series of cavities arranged one after another.
• All species have Frontal and Maxillary systems
  • Frontal: consists of space(s) within the bones between the cranial cavity and the 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 teeth. This increases with age due to wearing and ventral relocation of the teeth.

Function

• Resonating Cavities
• A mechanism for limiting the weight of the skull
• Insulation/Cooling of the brain
• Allow increased insertion space for teeth.

Species Differences

• In the Dog the sinus system is generally poorle developed. The Maxillary sinus is a cavity, freely communicating with the nasal cavity, and is known as the Maxillary Recess. The Frontal sinus has 3 chambers which drain separately into the 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.
• Cattle have a fully developed sinus system by the age of 7. The Frontal sinus in cattle has a 'diverticle' for the Cornual Process (horn).