CT Brain Anatomy
Meninges

Key points

  • Knowledge of anatomy of the meninges is essential for understanding the CT appearances of intracranial bleeding

The meninges are thin layers of tissue found between the brain and the inner table of the skull. The meninges comprise the dura mater, the arachnoid, and the pia mater. The dura mater and arachnoid are an anatomical unit, only separated by pathological processes.

The falx cerebri and the tentorium cerebelli are thick infoldings of the meninges which are visible on CT imaging. Elsewhere the meningeal layers are not visible on CT as they are closely applied to the inner table of the skull.

The meninges - CT brain

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The meninges

  • Dura mater = tough outermost layer, closely applied to the inner table of the skull
  • Arachnoid = thin layer closely applied to the dura mater
  • Subarachnoid space = space between the arachnoid mater and the pia mater which contains delicate trabeculated connective tissue and CSF
  • Pia mater = very thin layer applied to the surface of the brain

The meninges - clinical significance

  • Knowledge of anatomy of the meninges is essential for understanding the CT appearances of intracranial bleeding

Tentorium cerebelli - CT brain/axial image

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Tentorium cerebelli

  • The tentorium cerebelli - an infolding of the dura mater - forms a tent-like sheet which separates the cerebrum (brain) from the cerebellum
  • The tentorium is anchored by the petrous bones

Tentorium cerebelli - CT brain/axial image

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Tentorium cerebelli

  • On axial slice CT images of the brain the tentorium is faintly visible passing over the cerebellum

Tentorium cerebelli - clinical significance

  • In the context of subarachnoid haemorrhage or subdural haematoma the tent may become more dense due to layering of blood

Falx cerebri - CT brain/axial image

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Falx cerebri

  • The falx is an infolding of the meninges which lies in the midline and separates the left and right cerebral hemispheres

Falx cerebri - clinical significance

  • Pathological processes may cause 'mass effect' with deviation of the falx towards one side

Falx and tentorium - CT brain/coronal image

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Falx and tentorium - CT brain/coronal image

  • Coronal slice CT images show that the tentorium cerebelli is continuous with the falx cerebri

Falx and tentorium - clinical significance

  • Meningiomas are benign intracranial tumours which may arise from any part of the meninges, including the falx or tentorium