Cranial Veins, Dural Venous Sinuses, and Cerebral Veins

Cranial Veins, Dural Venous Sinuses, and Cerebral Veins

The venous system of the cranium consists of the dural venous sinuses, cerebral veins, and emissary veins, which drain venous blood from the brain, meninges, and skull into the internal jugular vein. Below is a detailed explanation based on Gray’s Anatomy and Sobotta Atlas of Human Anatomy.

1. Cranial Veins

The cranial veins can be divided into:

1.     Cerebral veins: Drain the brain parenchyma.

2.     Dural venous sinuses: Channels located between the layers of the dura mater.

3.     Emissary veins: Connect intracranial venous sinuses with extracranial veins.

4.     Diploic veins: Drain the spongy bone of the skull (diploë) into dural venous sinuses.

These veins are valveless, allowing bidirectional blood flow, which can contribute to the spread of infections.

2. Dural Venous Sinuses (Sinus Durae Matris)

The dural venous sinuses are endothelial-lined venous channels formed between the periosteal and meningeal layers of the dura mater. They receive blood from the cerebral veins, emissary veins, and diploic veins and drain into the internal jugular vein.

Key Dural Venous Sinuses

1.     Superior Sagittal Sinus:

a.     Located along the superior margin of the falx cerebri.

b.     Drains into the confluence of sinuses.

c.     Contains arachnoid granulations for CSF absorption.

2.     Inferior Sagittal Sinus:

a.     Lies along the inferior margin of the falx cerebri.

b.     Drains into the straight sinus.

3.     Straight Sinus:

4.     Formed by the union of the inferior sagittal sinus and the great cerebral vein (vein of Galen).

5.     Ends at the confluence of sinuses.

6.     Confluence of Sinuses:

a.     Located at the internal occipital protuberance.

b.     Drains into the transverse sinuses.

7.     Transverse Sinuses:

a.     Paired sinuses extending laterally from the confluence.

b.     Drain into the sigmoid sinuses.

8.     Sigmoid Sinuses:

a.     S-shaped sinuses that continue as the internal jugular veins.

9.     Cavernous Sinus:

a.     Located on either side of the sella turcica.

b.     Contains cranial nerves III, IV, V1, V2, and VI, as well as the internal carotid artery.

c.     Communicates with the facial vein via the ophthalmic veins, providing a route for infections (e.g., cavernous sinus thrombosis).

10.  Other Sinuses:

a.     Occipital sinus,

b.     superior and inferior petrosal sinuses,

c.     basilar plexus.

3. Cerebral Veins

The cerebral veins drain venous blood from the brain into the dural venous sinuses.

Types of Cerebral Veins:

1.     Superficial Cerebral Veins:

a.     Drain the cerebral cortex and lie within the subarachnoid space.

b.     Major veins:

                                              i.     Superior cerebral veins: Drain into the superior sagittal sinus.

                                            ii.     Superficial middle cerebral vein: Drains into the cavernous sinus.

                                           iii.     Superior and inferior anastomotic veins: Connect various venous sinuses.

2.     Deep Cerebral Veins:

a.     Drain deep brain structures such as the basal ganglia, thalamus, and internal capsule.

b.     Major veins:

                                              i.     Internal cerebral veins: Formed by veins draining the thalamus and caudate nucleus.

                                            ii.     Great cerebral vein (of Galen): Formed by the union of the internal cerebral veins, draining into the straight sinus.

3.     Clinical Correlations

a.     Cavernous Sinus Thrombosis:

                                              i.     Infections from the face (danger triangle) can spread to the cavernous sinus via emissary veins, leading to life-threatening thrombosis.

b.     Subdural Hematoma:

                                              i.     Tearing of bridging veins (connecting superficial cerebral veins to dural venous sinuses) can result in subdural hematomas.

c.     Hydrocephalus:

                                              i.     Obstruction of venous or CSF drainage (via arachnoid granulations into the superior sagittal sinus) can lead to increased intracranial pressure.