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A sinus is a sac or cavity in any organ or tissue, or an abnormal cavity or passage. 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. Most individuals have four paired cavities located in the cranial bone or skull.
Individuals may have more or fewer bones than the average (even accounting for developmental stage) owing to anatomical variations. The most common variations include sutural (wormian) bones , which are located along the sutural lines on the back of the skull, and sesamoid bones which develop within some tendons, mainly in the hands and feet.
Bone Cranial fossa Foramina Number Vessels Nerves frontal-supraorbital foramen: 2: supraorbital artery supraorbital vein: supraorbital nerve: frontal: anterior cranial fossa: foramen cecum: 1: emissary veins to superior sagittal sinus from the upper part of the nose [3] ethmoid: anterior cranial fossa (osama) foramina of cribriform plate ~20 ...
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 ...
Frontal sinus. Each frontal sinus is situated between the external and internal plates of the frontal bone. [1] [2] Their average measurements are as follows: height 28 mm, breadth 24 mm, depth 20 mm, creating a space of 6-7 ml. [3]
The sphenoid sinus is a paired paranasal sinus in the body of the sphenoid bone. It is one pair of the four paired paranasal sinuses. [1] The two sphenoid sinuses are separated from each other by a septum. Each sphenoid sinus communicates with the nasal cavity via the opening of sphenoidal sinus.
The sphenoid bone is in red (directly in the middle of the orbital cavity) Wedge-shaped sphenoid bone seen laterally. It is divided into the following parts: a median portion, known as the body of sphenoid bone, containing the sella turcica, which houses the pituitary gland as well as the paired paranasal sinuses, the sphenoidal sinuses [5]