The floor of the fourth ventricle the rhomboid fossa see fig.
Floor forth ventricle.
Csf produced and or flowing into the fourth ventricle can exit to the subarachnoid space through lateral apertures and a single median aperture located in the inferiorportion of the roof.
The fourth ventricle contains cerebrospinal fluid.
The fourth ventricle has a roof at its upper posterior surface and a floor at its lower anterior surface and side walls formed by the cerebellar peduncles nerve bundles joining the structure on the posterior side of the ventricle to the structures on the anterior side.
It is a non specific sign of a pontine mass or process with mass effect but in children is most frequently seen.
The cerebral aqueduct is a narrow canal in the midline connecting the third and fourth ventricle.
Specifically it spans from the obex an area in the medulla.
The fourth ventricle has an anterior ventral floor with a characteristic diamond shape named the rhomboid fossa and a posterior dorsal tent shaped roof.
10 3 is formed by the pons and medulla fig.
It has a diamond shape and is located in the upper portion of the medulla.
The caudal tip of the fourth ventricle where it becomes the central canal is known as the obex.
The flat floor of fourth ventricle sign is useful in detecting a pontine mass and is a sign of mass effect the normal floor of the fourth ventricle remember that the floor is anterior normally slopes upwards towards the midline with the facial colliculi visible on either side.
It is 1 5 cm long and 1 2 mm in diameter.
The only naturally occurring openings between the ventricles of the brain and the subarachnoid space surrounding the brain are the foramina of luschka and magendie in the fourth ventricle.