Emissary veins: The emissary veins connect the extracranial venous system with the intracranial venous sinuses. They connect the veins outside the cranium to the venous sinuses inside the cranium.Underwood's septa: In anatomy, Underwood's septa (or maxillary sinus septa, singular septum)Maestre-Ferrín L, et al. Maxillary sinus septa: a systematic review.Paranasal sinuses: Sinus}}Aortic sinus: An aortic sinus is one of the anatomic dilations of the ascending aorta, which occurs just above the aortic valve. These widenings are between the wall of the aorta and each of the three cusps of the aortic valve.Carotid sinus: In human anatomy, the carotid sinus (or carotid bulb) is a dilated area at the base of the internal carotid just superior to the bifurcation of the common carotid at the level of the superior border of thyroid cartilage. The carotid sinus is sensitive to pressure changes in the arterial blood at this level.Mucocele: A mucocele is any dilatation (typically pathologic) with accumulation of mucus. Examples include:Sick sinus syndromeSinonasal undifferentiated carcinoma: Sinonasal undifferentiated carcinoma, abbreviated SNUC, is a rare aggressive type of cancer that arises from epithelium or lining of the nose or sinuses.Sinoatrial arrest: Sinoatrial arrest (also known as sinus arrest or sinus pause) is a medical condition wherein the sinoatrial node of the heart transiently ceases to generate the electrical impulses that normally stimulate the myocardial tissues to contract and thus the heart to beat. It is defined as lasting from 2.