In the early embryo a primitive neural groove extending along the dorsal surface is converted into a tube by the elevation and the fusion of the neural folds. The cranial end of the neural tube forms the brain; it expands and constricts to form a series of three communicating sacs which are the primary brain vesicles known as the forebrain (prosencephalon), the midbrain (mesencephalon) and the hindbrain (rhombencephalon), the last being continuous with the spinal medulla. The cavity of the tube thus formed subsequently becomes the ventricular system and the central canal of the spinal cord, and the walls of the tube become the nerve elements of the brain and the spinal cord. The forebrain becomes the cerebral hemispheres and the optic vesicles; the midbrain develops into the brain stem connecting the cerebrum with the pons and the cerebellum, and the hindbrain forms the cerebellum, the pons and the medulla oblongata.
KeywordsCavernous Sinus Dura Mater Occipital Lobe Superior Sagittal Sinus Sella Turcica
Unable to display preview. Download preview PDF.