Many other smaller cavities exist throughout the body called Sinuses.

http://en.wikipedia.org/wiki/Human_body

Many other smaller cavities exist throughout the body called sinuses, which have varied functions. Sinuses in general usage refers to the paranasal sinuses which are involved in the condition sinusitis. The paranasal sinuses are four pairs of vital air-cavities in the cranial bones. These air-filled spaces are paired between the eyes, above the eyes, deeper behind the eyes and around the nasal cavity.