What makes the bones in sinus cavity look like sponge?
Sinuses are called Pneumatic bones.
So the bones are designed in a way which helps them to hold the air inside their bony structure.
This makes the bones of the sinuses to look like sponge.
Head is the heaviest structure in your body weighing about 5.5 kgs. So to make it feel lighter sinuses are designed to hold air inside(Pneumatic bones).
Hope the answer helps you.
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