MICROANATOMY

Detailed explanation-1: -A sinus is a sac or cavity in any organ or tissue, or an abnormal cavity or passage caused by the destruction of tissue. In common usage, “sinus” usually refers to the paranasal sinuses, which are air cavities in the cranial bones, especially those near the nose and connecting to it.

Detailed explanation-2: -The paranasal sinuses (the hollow spaces in the skull and facial bones around the nose) are air-filled cavities within the frontal, ethmoidal, sphenoidal, and maxillary bones. They are outgrowths from the nasal cavity. All of them drain into the superior or lateral aspect of the nose.

Detailed explanation-3: -One of many small hollow spaces in the bones around the nose. Paranasal sinuses are named after the bones that contain them: frontal (the lower forehead), maxillary (cheekbones), ethmoid (beside the upper nose), and sphenoid (behind the nose).

Detailed explanation-4: -What are sinuses? The sinuses are cavities, or air-filled pockets, near the nasal passage. As in the nasal passage, the sinuses are lined with mucous membranes.

Detailed explanation-5: -Two large frontal sinuses are located above your eyes and in your forehead. Two sphenoid and two ethmoid sinuses are set between your eyes and behind your nose. The largest two sinuses are the maxillary sinuses, and they are positioned under your eyes and behind your cheeks.