The Nose and Sinuses - Front View - CAT Scan
The maxillary sinus (black) is surrounded by bone (white). Soft tissue, such as the eye, is gray. The maxillary sinus of adults has a volume of 30 ml (2 tablespoons). Ciliary action moves sinus secretions up to the drainage passage, called the infundibulum. The drainage passage has a diameter the size of the lead in a pencil (3 mm). Mucus is moved out of the sinus cavity at the rate of 1 cm (3/8 inch) per minute.
