Cross section of<unk>  The<unk>  below at the ventricular system of the brain, beginning at a region called the obex where the fourth ventricle, a cavity present in the brainstem, narrows. The<unk>  is located in the third of the spinal cord in the cervical and thoracic regions. In the lumbar spine it enlarges and is located more<unk> ly. At the conus medullaris, where the spinal cord tapers, it is located more ly. Terminal ventricle The terminal ventricle (ventriculus terminalis, fifth ventricle or ampulla caudalis) is the widest part of the<unk>  of the spinal cord that is located at or near the conus medullaris. It was described by Stilling in 1859 and Krause in 1875. Krause introduced the term fifth ventricle after observation of normal ependymal cells. The<unk>  expands as a fusiform terminal ventricle, and approximately 8–10 mm in length in the conus medullaris (or conus terminalis). Although the terminal ventricle is visible in the fetus and children, it is usually absent in adults. Sometimes, the terminal ventricle is observed by MRI or ultrasound in children less than 5 years old. Microanatomy The<unk>  shares the same ependymal lining as the ventricular system of the brain. The<unk>  is lined by ciliated, column-shaped cells, outside of which is a band of gelatinous substance, called the substantia gelatinosa<unk> is (or<unk>  gelatinous substance of spinal cord). This gelatinous substance consists mainly of neuroglia, but contains a few nerve cells and fibers; it is traversed by processes from the deep ends of the columnar ciliated cells which line the<unk> . The substantia gelatinosa of Rolando, is located more dorsally. Development The<unk>  represents the adult remainder of the<unk>  cavity of the neural tube. It generally occludes (closes off) with age.
Central canal
Lacrimal groove
Craniopharyngeal canal
Optic recess
Lacrimal sac
Ateronon
Collateral fissure
Orbital septum