Subarachnoid cisterns

Subarachnoid cisterns
Diagram showing the positions of the three principal subarachnoid cisterns.
Details
Identifiers
Latin	cisterna
Anatomical terminology

The subarachnoid cisterns are spaces formed by openings, where the arachnoid mater and the pia mater are separated, in the subarachnoid space of the brain. These cisterns are filled with cerebrospinal fluid.

Although the pia mater adheres to the surface of the brain, closely following the contours of its gyri and sulci, the arachnoid covers only its superficial surface. It follows from this that in certain areas around the brain the pia and arachnoid are separated widely; in such regions cavities are formed called the subarachnoid cisterns.

Although they are often described as distinct compartments, the subarachnoid cisterns are not truly anatomically distinct. Rather, these subarachnoid spaces are separated from each other by a trabeculated porous wall with various-sized openings.

There are many cisterns in the brain with several especially large, notable ones each with their own name.

Some major subarachnoid cisterns:

• Cisterna magna also called cerebellomedullary cistern - the largest of the subarachnoid cisterns. It lies between the cerebellum and the medulla oblongata. It receives CSF from the fourth ventricle via the median aperture (foramen of Magendie). The cisterna magna contains:

1. The vertebral artery and the origin of the posterior inferior cerebellar artery (PICA).
2. The ninth (IX), tenth (X), eleventh (XI) and twelfth (XII) cranial nerves.

• Pontine cistern . Surrounds the ventral aspect of the pons. It receives CSF via the paired lateral apertures. It contains:

1. The basilar artery and the origin of the anteroinferior cerebellar artery (AICA).
2. The origin of the superior cerebellar arteries.
3. The sixth (VI) cranial nerve.

• Cerebellopontine angle cistern. It is situated in the lateral angle between the cerebellum and the pons. It contains:

1. The seventh (VII) and eighth (VIII) cranial nerves.
2. The anteroinferior cerebellar artery (AICA).
3. The fifth (V) cranial nerve and the petrosal vein.

• Interpeduncular cistern. It is situated at the base of the brain, between the two cerebral peduncles of midbrain and dorsum sellae and continuous below with pontine cistern and superiorly with suprasellar cistern. It contains:

1. The optic chiasm
2. The bifurcation of the basilar artery.
3. Peduncular segments of the posterior cerebral arteries (PCA).
4. Peduncular segments of the superior cerebellar arteries.
5. Perforating branches of the PCA.
6. The posterior communicating arteries (PCoA).
7. The basal vein of Rosenthal.
8. The third (III) cranial nerve, which passes between the posterior cerebral and superior cerebellar arteries.

• Superior cistern - It is situated dorsal to the midbrain. Thin, sheet-like extensions of the superior cistern that extend laterally about the midbrain, connecting it to the interpeduncular cistern. Ambient cistern may also refer to the combination of these extensions and the superior cistern. It is composed of a supratentorial and an infratentorial compartment.It contains:

1. The great cerebral vein.
2. The posterior pericallosal arteries.
3. The third portion of the superior cerebellar arteries.
4. Perforating branches of the posterior cerebral and superior cerebellar arteries.
5. The third portion of the posterior cerebral arteries.

Its supratentorial portion contains:

1. The basal vein of Rosenthal.
2. The posterior cerebral artery.

Its infratentorial portion contains:

1. The superior cerebellar artery.
2. The fourth (IV) nerve.

• Crural cistern. It is situated around the ventrolateral aspect of the midbrain. It contains:

1. The anterior choroidal artery.
2. The medial posterior choroidal artery.
3. The basal vein of Rosenthal.

• Carotid cistern. It is situated between the carotid artery and the ipsilateral optic nerve. It contains:

1. The internal carotid artery.
2. The origin of the anterior choroidal artery.
3. The origin of the posterior communicating artery.

• Insular/Sylvian cistern. It is situated in the fissure between the frontal and temporal lobes. It contains:

1. The middle cerebral artery.
2. The middle cerebral veins.
3. The fronto-orbital veins.
4. Collaterals to the basal vein of Rosenthal.

• Cistern of lamina terminalis. It is situated just rostral to the third ventricle. It contains:

1. The anterior cerebral arteries (A1 and proximal A2).
2. The anterior communicating artery.
3. Heubner's artery.
4. The hypothalamic arteries.
5. The origin of the fronto-orbital arteries.

• Lumbar cistern. It extends from the conus medullaris (L1-L2) to about the level of the second sacral vertebra. It contains the filum terminale and the nerve roots of the cauda equina. It is from the cistern that CSF is withdrawn during lumbar puncture.

It is of clinical significance that cerebral arteries, veins and cranial nerves must pass through the subarachnoid space, and these structures maintain their meningeal investment until around their point of exit from the skull.

References

• Nolte, J (2002) The Human Brain, 5th edition. ISBN 0-323-01320-1, 87