Fold of dura

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Head & Neck • Anatomy

FOLDS OF DURA MATER

Folds of dura mater described in the source include Falx cerebri, Tentorium cerebelli, Falx cerebelli and Diaphragma sellae.

01

Falx Cerebri

  • Falx cerebri is a large, sickle-shaped fold of dura mater.
  • It occupies the median longitudinal fissure between the two cerebral hemispheres.

Parts

A. Ends

It has two ends:

1. Anterior End

  • Narrow.
  • Attached to the crista galli.

2. Posterior End

  • Broad.
  • Attached along the median plane to the upper surface of the tentorium cerebelli.

B. Margins

It has two margins:

1. Upper Margin

  • Convex.
  • Attached to the lips of the sagittal sulcus.

2. Lower Margin

  • Concave.
  • Free.

C. Surfaces

  • It has right and left surfaces.
  • Each surface is related to the medial surface of the corresponding cerebral hemisphere.

Related Venous Sinuses

Three important venous sinuses are related to the falx cerebri:

1. Superior Sagittal Sinus

Lies along the upper margin.

2. Inferior Sagittal Sinus

Lies along the lower margin.

3. Straight Sinus

Lies along the line of attachment of the falx cerebri to the tentorium cerebelli.

02

Tentorium Cerebelli

  • Tentorium cerebelli is a tent-shaped fold of dura mater.
  • It forms the roof of the posterior cranial fossa.
  • It separates the cerebellum from the occipital lobes of the cerebrum.
  • It broadly divides the cranial cavity into:
  1. Supratentorial compartment
  2. Infratentorial compartment

The infratentorial compartment is the posterior cranial fossa containing the hindbrain and lower part of the midbrain.

Parts

Margins

The tentorium cerebelli has:

  1. Free margin
  2. Attached margin.

1. Anterior Free Margin

  • It is U-shaped and free.
  • The ends of the U are attached anteriorly to the anterior clinoid processes.
  • This margin bounds the tentorial notch.
  • The tentorial notch is occupied by:
  1. Midbrain
  2. Anterior part of the superior vermis.

2. Outer or Attached Margin

It is convex.

Posterolaterally

  • Attached to the lips of the transverse sulci on the occipital bone.
  • Attached to the posteroinferior angle of the parietal bone.

Anterolaterally

Attached to:

  • Superior border of the petrous temporal bone
  • Posterior clinoid processes.

Venous Sinuses Along Attached Margin

  • Transverse venous sinus
  • Superior petrosal venous sinus.

Surfaces of Tentorium Cerebelli

It has two surfaces:

  1. Superior surface
  2. Inferior surface.

1. Superior Surface

  • It is convex.
  • It slopes to either side from the median plane.
  • The falx cerebri is attached to this surface in the midline.
  • The straight sinus lies along the line of this attachment.
  • It is related to the occipital lobes of the cerebrum.

2. Inferior Surface

  • It is concave.
  • It fits the convex superior surface of the cerebellum.
  • The falx cerebelli is attached to its posterior part.

Note: Trigeminal or Meckel’s Cave

  • The trigeminal or Meckel’s cave is a recess of dura mater related to the attached margin of the tentorium.
  • It is formed by evagination of the inferior layer of the tentorium over the trigeminal impression on the petrous temporal bone.
  • It contains the trigeminal ganglion.

Relation of Free and Attached Margins

  • The free and attached margins of the tentorium cerebelli cross each other near the apex of the petrous temporal bone.
  • Anterior to the point of crossing:
  • There is a triangular area.
  • It forms the posterior part of the roof of the cavernous sinus.
  • It is pierced by the 3rd and 4th cranial nerves.
03

Falx Cerebelli

  • Falx cerebelli is a small, sickle-shaped fold of dura mater.
  • It projects forwards into the posterior cerebellar notch.

Parts

1. Base

The base of the sickle is attached to the posterior part of the inferior surface of the tentorium cerebelli in the median plane.

2. Apex

  • The apex of the sickle is frequently divided into two parts.
  • These are lost on the sides of the foramen magnum.

3. Posterior Margin

  • Convex.
  • Attached to the internal occipital crest.
  • Encloses the occipital sinus.

4. Anterior Margin

  • Concave.
  • Free.
04

Diaphragma Sellae

  • Diaphragma sellae is a small, circular, horizontal fold of dura mater.
  • It forms the roof of the hypophyseal fossa.
  • It has a central aperture.
  • The stalk of the hypophysis cerebri passes through this aperture.

Attachments

1. Anteriorly

To the tuberculum sellae

2. Posteriorly

To the dorsum sellae

3. On Each Side

Continuous with the dura mater of the middle cranial fossa.

05

Clinical Anatomy

1. Pain-Sensitive Intracranial Structures

The pain-sensitive intracranial structures are:

  1. Large cranial venous sinuses and their tributaries from the surface of the brain
  2. Dural arteries
  3. Dural floor of the anterior and posterior cranial fossae
  4. Arteries at the base of the brain.

2. Headache

Headache may be caused by:

  1. Dilatation of intracranial arteries
  2. Dilatation of extracranial arteries
  3. Traction or distension of intracranial pain-sensitive structures
  4. Infection and inflammation of intracranial and extracranial structures supplied by the sensory, cranial and cervical nerves.

3. Extradural and Subdural Haemorrhages

The differences between extradural and subdural haemorrhages are listed in Table 12.1 in the source.

FOLDS OF DURA MATER
Anatomy study notes.