Meningiomas are named according to their location (Fig 1) and cause various symptoms: 1  Convexity meningiomas: grow on the surface of the brain. They may not produce symptoms until they reach a large size. 2  Falx and parasagittal meningiomas: grow from the dura fold that runs between the left and right sides of the brain.
Tectum | Tegmentum | See also. The midbrain, or mesencephalon is made up of two main structures and surrounds the cerebral aqueduct.he midbrain, or mesencephalon is made up of two main structures and surrounds the cerebral aqueduct.
Although it is often referred to as one structure, the substantia nigra is actually made up of two anatomically and functionally distinct portions: the substantia nigra pars compacta and the substantia nigra pars reticulata. Neurons in the pars compacta are much more densely packed together (or compact) than those in the pars reticulata.