Sinus Anatomy. INTRODUCTION. The paranasal sinuses (âthe sinusesâ) are air-filled cavities located within the bones of the face and around the nasal cavity and eyes. Each sinus is named for the bone in which it is located: Physiology.The pink membranes lining the sinuses make mucus that is cleared out of the sinus cavities and drains into the nasal passage. The right and left nasal passages are separated in the middle by a vertical plate of cartilage and bone called the nasal septum (figures 1 and 2).ach sinus is named for the bone in which it is located: Physiology. The pink membranes lining the sinuses make mucus that is cleared out of the sinus cavities and drains into the nasal passage.
[freÂ´kwen-se] 1. the number of occurrences of a periodic or recurrent process in a unit of time, such as the number of electrical cycles per second measured in hertz. In cardiac pacing terminology, frequency is expressed by the formula: frequency = Â½ Ã pulse width.
The standard unit of frequency is the hertz, abbreviated Hz. If a current completes one cycle per second, then the frequency is 1 Hz; 60 cycles per second equals 60 Hz (the standard alternating-current utility frequency in some countries).