Tentorium cerebelli

Anatomy

The brain and spinal cord are enveloped by the meninges, which serve to protect them from mechanical trauma, provide support to blood vessels and a passageway for the cerebrospinal fluid (CSF). From innermost to outermost, the meninges consist of the following three layers: pia mater, arachnoid mater, and dura mater.

The dura mater is a strong, double-layered membrane, composed of the periosteal layer, which adheres to the periosteum of the neurocranium, and the meningeal layer, which surrounds the brain and spinal cord. In some regions and fissures of the brain, the meningeal layer of dura mater projects inwards to form four dural partitions: the falx cerebri, falx cerebelli, tentorium cerebelli, and sellar diaphragm.

The tentorium cerebelli is the second-largest dural reflection that extends over the posterior cranial fossa. It separates the occipital and temporal lobes of the cerebrum from the underlying cerebellum and brainstem, and divides the cranial cavity into supratentorial and infratentorial spaces.

The tentorium cerebelli is attached almost along the entire circumference of the posterior cranial fossa with its outer (posterior and lateral) margins, which are fixed and convex. The inner (anterior) margin is free and concave, and forms a U-shaped hiatus.

• The posterior margin is attached to the internal occipital protuberance in its most posterior aspect, and continues along the lips of the groove for transverse sinus. As it extends further anteriorly, it attaches to the posteroinferior angles of the parietal bone.
• The lateral margin is attached to the superior border of the petrous part of the temporal bone, and extends anteriorly to attach on the posterior clinoid process. As it reaches the apex of the petrous temporal bone, it continues anteriorly as a dural ridge called the posterior petroclinoidal ligament.
• The free anterior margin contains a large U-shaped hiatus called the tentorial notch, which provides passage to the midbrain and the superior aspect of the cerebellar vermis. In addition, the splenium of the corpus callosum occupies a small part of the tentorial notch. The rim of the tentorial notch is attached to the apex of the petrous temporal bone and extends anteriorly as the anterior petroclinoidal ligament to attach to the anterior clinoid process.

Struggling to understand the meninges and dural septa? Make your life easier and learn all the parts of the brain with our diagrams and quizzes!

Relations

The tentorium cerebelli contributes to the formation of several dural venous sinuses and one dural recess:

• The posterior margin of the tentorium cerebelli houses the transverse sinus, running along the groove for transverse sinus on the occipital bone.
• The superior surface of the posterior part of the tentorium cerebelli blends with the falx cerebri. This line of attachment contains the straight sinus.
• The lateral margin of the tentorium cerebelli houses the superior petrosal sinus, which runs in the superior border of the petrous part of temporal bone.
• The site where the free anterior margin adheres to the anterior clinoid process forms the lateral part of the cavernous sinus.
• Near the apex of the petrous temporal bone, the lower layer of the tentorium is evaginated anterolaterally under the superior petrosal sinus to form a dural recess, the Meckel’s cave. Meckel's cave houses the posterior root of the trigeminal nerve and the trigeminal ganglion.

To learn more about the dural venous sinuses, check out our study unit below, and then take the custom quiz to see how well you retained the information!

Function

As higher primates evolved from quadrupedal to bipedal locomotion with erect posture, the tentorium cerebelli came into play to support the extra weight of the brain that shifted from the anterior aspect, to the superior aspect of the cervical spine. Thereby, the tentorium cerebelli adds strength to the axial midline and dispels the burden of weight from supratentorial structures on the infratentorial structures.

In addition, it is thought that the dural folds, and especially the falx cerebri and the tentorium cerebelli, play an important role in the development and functional loading of the cranium. In other words, dural folds determine the cranial suture sites and their absence is accompanied by a lack of suture formation.

Now that you’ve completed this lesson, take the following quiz to test and consolidate your knowledge about the tentorium cerebelli and other meningeal structures of the brain!