Emissary veins passing through the foramen ovale, jugular foramen, foramen lacerum, and hypoglossal canal. Because the emissary veins are valveless, they are an important part in selective brain cooling through bidirectional flow of cooler blood from the evaporating surface of the head. In general, blood flow is from external to internal but the flow can be altered by increased intracranial pressure. A type of emissary vein goes through the sphenoidal emissary foramen inferior to the zygomatic arch with the cavernous sinus on the inside of the skull. This is an important route for spread of infection because cranial nerve VI and the
Myoepithelioma of the head and neck Myoepithelioma of the head and neck Myoepithelioma of the head and neck, also myoepithelioma, is a salivary gland tumour of the head and neck that is usually benign. As the name suggests, it consists of myoepithelial cells. Classically, they are found in the parotid gland or palate. A similar tumor type may be found in the tongue, referred to as ectomesenchymal chondromyxoid tumor. The myoepithelial cells may be spindled, plasmacytoid, eithelioid or clear. Tubules or epithelium are absent, or present in a small amount (<5%) by definition. Tumours with myoepithelial cells and a large amount of tubules are classified as