ExplanationD. • Pneumatic bones are those bones which contain an air filled cavity within them which make them light in weight. In humans, they are seen in relation to the nasal cavity, and enclose the paranasal sinuses. Besides making the skull light in weight, they also help in resonance of sound and act as air conditioning chambers for the inspired air. • Pneumatic bones are–maxilla, frontal bone, sphenoid and ethmoid. • The mastoid is also most commonly a pneumatic (air filled) bone which encloses numerous air cell spaces giving it a honeycomb appearance. However in some people the mastoid may be diploic (marrow filled) or sclerotic (solid bone without air).
