Emissary Veins

These connect extracranial and intracranial venous systems. They form routes for spread of infection and malignancies. Also provide alternative route for venous blood.

  • Frontal
  • Parietal (shown in the image)
  • Mastoid
  • Condylar

Locate the foramina for these veins.
 
Weak points of the skull
  • Pterion
  • Squamous temporal
  • Orbital walls
  • Nasal walls

Identify the bones forming the pterion on the skull shown

 
Cranial meningeal extensions

The most important one clinically, is that surrounding the optic nerve.

By presence of this extension, the optic nerve and central vessels of retina may be compressed in increased intracranial pressure. This causes oedema of the retina especially the papilla or disc.

This is called papilloedema.