Cisterns of the brain

---
config:
  theme: redux-dark-color
---
mindmap
  root((Liliequist classification of C.S.F. cisterns))
    Ventral Cisterns
      Median unpaired
        Medullary
        Pontine
        Interpeduncular
        Chiasmatic
      Paramedian paired
        CP angle
        Crural
        Carotid
        Sylvian
    Dorsal Cisterns
      Median unpaired
        Peri-callosal
        Quadrigemial
        Supra-cerebellar
      Paramedian paired
        Ambient
        Retro-thalamic
    Communicating cisterns
      Cisterna magna
      Lamina terminalis
    General subarachnoid space over the convexities

Perimesencephalic cistern

Interpeduncular cistern (1)

• Unpaired cistern located centrally at the base of the brain in the transition zone between the supratentorial and infratentorial spaces.

• Location and General Structure
• The cistern is situated in the posterior part of the anterior incisural space.
• It is located between the cerebral peduncles.
• This cistern lies directly below the floor of the third ventricle and the midbrain.
• The area in the upper part of the cistern, behind the mamillary bodies and below the floor of the third ventricle, is sometimes referred to as the interpeduncular fossa.
• The interpeduncular cistern is where the supratentorial and infratentorial parts of the subarachnoid space meet.

• Boundaries and Membranes
• The cistern is partially or completely separated from adjacent spaces by inner arachnoid membranes.
• It is bounded by the two components of Liliequist’s membrane

• Contents and Neurovascular Relationships
• Basilar artery bifurcation (basilar apex)
• Origin of the P1 segments of the PCA
• The P1 segment of the PCA gives rise to posterior thalamoperforating arteries that course through the cistern and enter the brainstem via the posterior perforated substance located behind the mamillary bodies.
• SCA usually arises near the basilar apex and courses laterally along the lower side of the mesencephalic membrane.
• CN III arises from the midbrain and travels within the cistern.

• Clinical and Surgical Significance
• Aneurysms arising at the basilar apex are located in the interpeduncular cistern.
• Aneurysms arising at the basilar apex and the origin of the SCA may project into the diencephalic and mesencephalic leaves of Liliequist’s membrane.
• Five arachnoid membranes, including the diencephalic and mesencephalic membranes, converge on the oculomotor nerve; traction on any of these membranes during surgery may pose a risk to associated aneurysms.
• The cistern can be accessed during endonasal endoscopic surgery via an approach that involves drilling the dorsum sellae, which exposes the mesencephalic leaf of Liliequist’s membrane and the contents of the interpeduncular cistern, including the PCA origins and thalamoperforating arteries.

Crural cistern (2)

• Has been named as the space limited laterally by the uncus, medially by the crus cerebri, and superiorly by the optic tract

• Borders
• Located between the cerebral peduncle and uncus
• Roofed by the optic tract
• It connects the carotid cistern anteriorly to the ambient cistern posteriorly.

• Ends with the entry of the anterior choroidal artery into the temporal horn

• The crural cistern cannot be reached through the choroidal fissure because the fissure ends just behind the uncus at the inferior choroidal point.
• The crural cistern can be exposed from the temporal horn by an incision extending forward from the inferior choroidal point through the amygdala.

• Contents
• Basal vein
• Cisternal segment of the anterior choroidal artery
• P2A segments of the posterior cerebral artery

Ambient cistern (3)

• Continues posteriorly between the parahippocampal gyrus and the brainstem

• Borders
• Medially by the midbrain
• Above by the pulvinar
• Laterally by the parahippocampal and dentate gyri and the fimbria of the fornix.

• The cisternal side of the temporal portion of the choroidal fissure is located in the superolateral part of the ambient cistern between the fimbria and the lower thalamic surface.

• There are still some controversies regarding the boundaries between the crural and ambient cisterns.

Quadrigeminal cistern (4)

• Aka: Pineal region

• Has a roof, floor, and anterior and lateral walls.
• The choroid fissure lies at the junction of the anterior and lateral walls of the quadrigeminal cistern.
• Lateral walls
• Of the quadrigeminal cistern separate the cistern from the atria.
• Each lateral wall has 2 parts:
• Anterior part is formed by the crus of the fornix
• Posterior part is formed by the part of the medial surface of the occipital lobe situated below the splenium.
• Anterior wall of the cistern
• 2 parts.
• Medial part:
• Formed by the quadrigeminal plate and pineal body.
• The suprapineal recess of the third ventricle bulges into the cistern above the pineal body.
• Lateral part:
• Formed by the part of the pulvinar that lies medial to the crus of the fornix.
• Below the colliculi, the cistern extends into the cleft between the midbrain and cerebellum called the cerebellomesencephalic fissure.
• This fissure cannot be reached through the choroidal fissure.
• The trochlear nerves arise below the inferior colliculi and course laterally around the midbrain and below the pulvinars to enter the ambient cisterns.
• Roof of the cistern is formed by the lower surface of the splenium and the broad membranous envelope that surrounds the great vein and its tributaries.
• This broad envelope of arachnoid tissue is applied to the lower surface of the splenium and is continuous anteriorly with the velum interpositum.
• It is within this envelope, in the superomedial part of the cistern, that the venous structures are found in the greatest density.
• The superomedial location of the major veins in the cistern contrasts with the location of the large arteries that are found in the inferolateral part of the cistern.

• Communications with the quadrigeminal cistern
• The quadrigeminal cistern opens anteriorly below the pulvinars into the ambient cisterns.
• The quadrigeminal cistern may communicate with the velum interpositum.
• Another potential cavity that may communicate with the quadrigeminal cistern is the cavum vergae, which is located immediately above the velum interpositum between the hippocampal commissure and the splenium.
• The cavum vergae is infrequently present because the hippocampal commissure commonly fuses to the lower surface of the splenium

 

Images