Paranasal Sinuses

Development

• The ethmoid and maxillary sinuses are usually present at birth
• The sphenoid develops 2-3 years after birth
• The frontal sinus is occasionally present at birth but usually appears around 2 years
• They all continue to develop until puberty
• Lined with mucoperiosteum and pseudostratified columnar ciliated epithelium

• All drain lymph to submandibular nodes except sphenoid and posterior ethmoidal which drain to retropharyngeal nodes

• All drain into middle meatus except sphenoid sinus (sphenoethmoidal recess) and posterior ethmoidal air cells (superior meatus)

Maxillary sinus

• Largest
• Located in body of maxilla
• Connects to the nose via an opening in its base piercing the hiatus semilunaris
• Drains to middle meatus

• Nerve supply: infraorbital nerve (continuation of maxillary nerve), anterior, middle and posterior superior alveolar nerves

• Arterial supply: anterior and posterior superior alveolar branches of the infraorbital and maxillary arteries

Frontal sinus

• Within frontal bone
• Connects with nose via frontonasal duct or ethmoid infundibulum
• Drains to middle meatus
• Nerve supply: supraorbital nerve (branch of the ophthalmic nerve)
• Arterial supply: supraorbital and anterior ethmoidal arteries

Sphenoid sinus

• Within sphenoid
• Variable extent and development
• Drains into sphenoethmoidal recess above superior concha
• Nerve supply: posterior ethmoidal nerves
• Arterial supply: posterior ethmoidal arteries
• Lymph: retropharyngeal nodes

Ethmoid sinus

• Honeycomb of air cells
• Separated from orbit by lamina papyracea
• Anterior and middle groups drain into middle meatus
• Posterior group drains into superior meatus

• Nerve supply: anterior and posterior ethmoidal nerves and branches of pterygopalatine ganglion

• Arterial supply: anterior and posterior ethmoidal arteries and sphenopalatine artery