A patient with an infected scalp wound develops meningitis. Spread of infection from the scalp veins into the superior sagittal sinus is thought to occur through small valveless channels that pierce the skull. These channels are called:

• A Diploic veins
• B Emissary veins ✓
• C Bridging cerebral veins
• D Venae comitantes of the meningeal arteries

Explanation

Emissary veins are valveless channels that pass through cranial foramina such as the parietal and mastoid foramina, connecting the extracranial scalp and diploic veins with the dural venous sinuses. Because they lack valves, flow can reverse and infected scalp material can reach the superior sagittal sinus, producing septic thrombosis and meningitis. Diploic veins lie entirely within the diploe of the skull bones and do not traverse the full thickness of the vault, while bridging veins drain brain parenchyma.

Reference: Gray's Anatomy, 42nd ed.

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Written and medically reviewed by the StethoPrep medical team.