The<unk>  is a rhombus-shaped depression that is the anterior part of the fourth ventricle. Its anterior wall, formed by the back of the pons and the medulla oblongata, constitutes the floor of the fourth ventricle. It is covered by a thin layer of grey matter continuous with that of the spinal cord; superficial to this is a thin lamina of neuroglia which constitutes the ependyma of the ventricle and supports a layer of ciliated epithelium.
Rhomboid fossa
Canine fossa
Suboccipital triangle
Collateral fissure
Kernohan's notch
Transverse sinuses
Fontanelle
Cortical homunculus