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Frontal sinuses are rarely symmetrical as the septum between them frequently deviates to either side of the midline. [3] [1] The two sinuses also vary in extent compared to one another. [2] Their size of the frontal sinuses is highly variable. [2] Rarely, one or both sinuses is hypoplastic [1] or even absent. [1] [2]
The common cardinal veins, also known as the ducts of Cuvier, [1] are veins that drain into the sinus venosus during embryonic development. [2] [3] These drain an anterior cardinal vein and a posterior cardinal vein on each side. [2] [3] Each of the ducts of Cuvier receives an ascending vein.
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 ...
The frontal sinuses are located in the frontal bone; the sphenoidal sinuses in the sphenoid bone; the maxillary sinuses in the maxilla; and the ethmoidal sinuses in the ethmoid bone. [2] [13] A narrow opening called a sinus ostium from each of the paranasal sinuses allows drainage into the nasal cavity. The maxillary sinus is the largest of the ...
Maya chacmool from Chichen Itza, excavated by Le Plongeon in 1875, now displayed at the National Museum of Anthropology in Mexico City. A chacmool (also spelled chac-mool or Chac Mool) is a form of pre-Columbian Mesoamerican sculpture depicting a reclining figure with its head facing 90 degrees from the front, supporting itself on its elbows and supporting a bowl or a disk upon its stomach.
The frontal crest of the frontal bone ends below in a small notch which is converted into a foramen, the foramen cecum (or foramen caecum), by articulation with the ethmoid. The foramen cecum varies in size in different subjects, and is frequently impervious; when open, it transmits the emissary vein from the nose to the superior sagittal sinus.
The frontonasal duct is a duct through which either frontal sinus drains into the nasal cavity. [2] [3] Each frontal sinus opens into the frontonasal duct by an opening (the opening of frontal sinus or frontal sinus aperture [4]) on the inferomedial part [3] of the floor of the sinus. [4]
The sinus venosus is a large quadrangular cavity which precedes the atrium on the venous side of the chordate heart. [1] [verification needed]In mammals, the sinus venosus exists distinctly only in the embryonic heart where it is found between the two venae cavae; in the adult, the sinus venosus becomes incorporated into the wall of the right atrium to form a smooth part called the sinus ...