| Obex | |
|---|---|
 Hind-brain of a human embryo of three months—viewed from behind and partly from left side. | |
 Rhomboid fossa. | |
| Details | |
| Identifiers | |
| Latin | obex |
| NeuroNames | 636 |
| NeuroLex ID | nlx_151877 |
| TA98 | A14.1.04.021 A14.1.05.723 |
| TA2 | 5982 |
| FMA | 78490 |
| Anatomical terms of neuroanatomy | |
The obex (from Latin 'barrier') is the point in the human brain at which the fourth ventricle narrows to become the central canal of the spinal cord. Cerebrospinal fluid can flow from the fourth ventricle into the obex. In anatomical studies, the obex has been found to occur approximately 10-12 mm above the level of the foramen magnum. In patients with low tonsillar position, the obex has been found below the plane of the foramen magnum.[1]
The obex occurs in the caudal medulla.
The decussation of sensory fibers happens at this point.
- ^ Weerakkody, Yuranga; Jones, Jeremy (24 March 2009). "Obex". Radiopaedia.org. doi:10.53347/rID-5851. Retrieved 23 January 2023.