Local anaesthetic solution spreads laterally within the epidural space with major entry in the 'dural cuff' region. Rapid entry into the CSF occurs via the arachnoid granulations in this region.

Direct diffusion across the dura also occurs.

Modified with permission from: Figure 8.2 p 256 Cousins MJ and Bridenbough PO. 'Neural Blockade' 2nd edition. JB Lippincott. Philadelphia.