This section passes through the apex of the skull vault and traverses the parietal bones (2) and the superior portion of the frontal bone (1).
Between the inner and outer tables of the bones of the skull vault lie trabecular bone, termed diploe, which contains red bone marrow. This is highly vascular and a common site for blood-borne metastatic tumour deposits and multiple myeloma. Diploic veins (see (8) on page 18) occupy channels in this trabecular bone. These are absent at birth but begin to appear at about 2 years of age. They are large and thin-walled, being merely endothelium supported by elastic tissue, and they communicate with meningeal veins, dural sinuses and the pericranial veins. Radiographically they may appear as relatively transparent bands 3-4mm in diameter.