Main page/Tentorium

Tentorium

Tentorial incisura spaces

  • Important landmarks
      • Space
      Neural Structures
      Vascular Structures
      Lateral
      Lateral surface of midbrain
      Anterior choroidal artery
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      Upper pons
      Posterior cerebral artery
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      Medial surface of temporal lobe
      Superior cerebellar artery
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      Fourth and fifth cranial nerves
      Basal vein of Rosenthal
      Posterior
      Pineal region
      Internal cerebral veins
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      Quadrigeminal plate
      Posterior basal veins
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      Fourth cranial nerve
      Vein of Galen
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      Straight sinus

Tentorial Incisura

  • The lateral and third ventricles are situated above the tentorial incisura, the triangular space situated between the free edges of the tentorium and the dorsum sellae
  • The apex of the incisura is dorsal to the midbrain in the area posterior to the pineal body, and the base is on the dorsum sellae.
  • The midbrain is situated in the center of the incisura.
  • The area between the midbrain and the free edges is divided into
    • The three incisural spaces contain some of the basal cisterns and are so intimately related to the lateral ventricles that some operative approaches to the basal cisterns situated within the incisura are directed through the lateral ventricles and choroidal fissure.
      • Anterior incisural space
      • Located anterior to the midbrain
      • The frontal horns are located above the anterior incisural space
      • Extends obliquely upward around the optic chiasm along the anterior wall of the third ventricle to the area below the rostrum of the corpus callosum and the floor of the frontal horn.
      • Contains the
        • Interpeduncular cistern, which is situated between the cerebral peduncles,
        • Chiasmatic cistern, which is located below the optic chiasm.
          • The chiasmatic cistern communicates around the optic chiasm with the cisternal laminae terminalis, which lies anterior to the lamina terminalis in the area below the floor of the frontal horn.
      Middle incisural spaces (paired)
      • Located
        • Lateral to the midbrain
        • Between the temporal lobe and the midbrain
          • Is so intimately related to the temporal horn and temporal part of the choroidal fissure that some operative approaches to this space are directed through the temporal horn.
      • Ventricular relations
        • The bodies of the lateral ventricles are located directly above the central part of the incisura, where they sit on and are separated from the central part of the incisura by the thalamus.
        • The temporal horns
          • Are situated superolateral to the middle incisural space.
          • Ends approximately 3 cm from the anterior pole of the temporal lobe.
      • Cisterns within the space
        Posterior incisural space
        • Located
          • Medial to the atrium.
          • Located behind the midbrain.
        • Ventricular relations
          • The atria are located above the posterior incisural space.
        • Contains
      Oblique view of the left tentorial incisura (lateral space) showing its neurovascular structures. The left tentorial edge is elevated with a dissector, displaying the trochlear nerve (tr.n.) running parallel to the tentorial margin to its entrance into the cavernous sinus. The oculomotor nerve (oc.n.) enters into the roof of the cavernous sinus. Beneath the trochlear nerve, the trigeminal nerve (tg.n.) passes through Meckel’s cave. Note the close relationship between the trigeminal nerve and the superior cerebellar artery (sca). Basilar artery (ba); internal carotid artery (ica); midbrain (mb); optic nerve (o.n.); posterior communicating artery (pca); and third ventricle (3v).
      Oblique view of the left tentorial incisura (lateral space) showing its neurovascular structures.
      The left tentorial edge is elevated with a dissector, displaying the trochlear nerve (tr.n.) running parallel to the tentorial margin to its entrance into the cavernous sinus.
      The oculomotor nerve (oc.n.) enters into the roof of the cavernous sinus.
      Beneath the trochlear nerve, the trigeminal nerve (tg.n.) passes through Meckel’s cave. Note the close relationship between the trigeminal nerve and the superior cerebellar artery (sca).
      Basilar artery (ba); internal carotid artery (ica); midbrain (mb); optic nerve (o.n.); posterior communicating artery (pca); and third ventricle (3v).
      Superior view of the tentorial notch displaying its neurovascular relationships. Basilar artery (ba); cerebellum (ce); internal carotid artery (ica); midbrain (mb); oculomotor nerve (oc.n.); optic nerve (o.n.); pituitary stalk (ps); posterior communicating artery (pca); superior cerebellar artery (sca); and trochlear nerve (tr.n.).
      Superior view of the tentorial notch displaying its neurovascular relationships.
      Basilar artery (ba); cerebellum (ce); internal carotid artery (ica); midbrain (mb); oculomotor nerve (oc.n.); optic nerve (o.n.); pituitary stalk (ps); posterior communicating artery (pca); superior cerebellar artery (sca); and trochlear nerve (tr.n.).
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      Dural septa

      Function

      • Partition and maintain the positions of the intracranial neural structures

      Falx cerebri

      • Lies in the deep fissure between the two hemispheres of the cerebrum.
      • Attachment
        • Anterior attachment at the crista galli of the cribriform plate
        • Posterior attachment superior surface of the tentorium.
        • Superiorly it attaches to the midline of the frontal, parietal, and occipital bones,
        • Inferiorly it remains unattached.
          • Posteriorly the inferior free edge closely opposes the corpus callosum,
          • Anteriorly there is a wide space between the two structures where the cerebral hemisphere can herniate beneath the free edge
      • The sickle-shaped falx is shorter in its anterior portion.

      Tentorium cerebelli

      • Divides the cranium into the supratentorial and infratentorial compartments.
      • Incisura: Free edge of the tentorium
      • Attachment
        • Inner surface of the temporal, parietal, and occipital bones at its margins.
        • Anteriorly, the free edges of the incisura pass over the trigeminal ganglion to insert onto the petrous apex and the anterior and posterior clinoid processes.
          • These insertions form three dural fold/ligaments: (Aka oculomotor trigone, through which the oculomotor nerve enters the cavernous sinus)
            • Anterior petroclinoid fold/ligaments
            • Posterior petroclinoid fold/ligaments
            • Interclinoid fold/ligaments
              • The medial extension of the dura covering the oculomotor trigone is the diaphragma sellae. Dura extending anteriorly from the free edge will form the lateral wall of the cavernous sinus and cover the middle cranial fossa.
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      Diaphragma sellae

      • Layers of the dura also separate around the sella and parasellar regions and the Meckel cave.

      Falx cerebelli