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The paranasal sinuses are joined to the nasal cavity via small orifices called ostia. These become blocked easily by allergic inflammation, or by swelling in the nasal lining that occurs with a cold. If this happens, normal drainage of mucus within the sinuses is disrupted, and sinusitis may occur. Because the maxillary posterior teeth are ...
In the anatomy of the heart, the valve of the coronary sinus (also called the Thebesian valve, after Adam Christian Thebesius [1] [2] [3]) is a valve located at the orifice of the coronary sinus where the coronary sinus drains into the right atrium. [4] It prevents blood from flowing backwards into the coronary sinus during contraction of the ...
The four paired sinuses or air cavities can be referred to as: Ethmoid sinus cavities which are located between the eyes. Frontal sinus cavities which can be found above the eyes (more in the forehead region). Maxillary sinus cavities are located on either side of the nostrils (cheekbone areas).
The four pairs of paranasal sinuses – the maxillary, ethmoid, sphenoid, and frontal, develop from the nasal cavity as invaginations extending into their named bones. Two pairs of sinuses form during prenatal development and two pairs form after birth. The maxillary sinuses are the first to appear during the fetal third month.
The heart is a muscular organ situated in the mediastinum.It consists of four chambers, four valves, two main arteries (the coronary arteries), and the conduction system. The left and right sides of the heart have different functions: the right side receives de-oxygenated blood through the superior and inferior venae cavae and pumps blood to the lungs through the pulmonary artery, and the left ...
The ethmoid sinuses or ethmoid air cells of the ethmoid bone are one of the four paired paranasal sinuses. [1] Unlike the other three pairs of paranasal sinuses which consist of one or two large cavities, the ethmoidal sinuses entail a number of small air-filled cavities ("air cells"). [ 2 ]
As heart development continues, this tube undergoes remodeling to eventually form the four-chambered heart. The endocardial cushions are a subset of cells found in the developing heart tube that will give rise to the heart's primitive valves and septa , critical to the proper formation of a four-chambered heart.
The coronary sinus runs transversely in the left atrioventricular groove (coronary sulcus) on the posterior aspect of the heart. [5] The sinus, before entering the right atrium, is considerably dilated - nearly to the size of the end of the little finger.