Arachnoid Mater in a Section of the Skull, Gross Anatomy

Description

Presented in a cranial section with the calvaria removed, the arachnoid mater spans the inner aspect of the skull deep to the dura mater and superficial to the pia mater, bridging over the cerebral sulci rather than dipping into them. Fine arachnoid trabeculae extend inferiorly across the subarachnoid space toward the pial surface, where cerebrospinal fluid and the larger cerebral arteries typically course. Along the inner table, the dural lining relates to bony landmarks and foramina at the skull base, while the meningeal layers maintain their layered arrangement from superficial dura to deeper arachnoid and pia. Arachnoid anatomy matters because the subarachnoid space is the compartment that fills with blood in aneurysmal subarachnoid hemorrhage, and it is the same space accessed intentionally during lumbar puncture and intrathecal drug delivery. The arachnoid also forms sleeves around traversing structures and contributes to CSF resorption via arachnoid granulations into the dural venous sinuses, a point that clarifies why impaired resorption can lead to communicating hydrocephalus. Small structure, big consequences. Use this illustration in neuroanatomy and head and neck anatomy teaching to distinguish dura, arachnoid, and pia in situ, and in clinical education materials explaining meningeal hemorrhage patterns (epidural vs subdural vs subarachnoid) and their expected compartments. It also fits neurosurgery or neuroradiology texts that need a clean cross-sectional reference for meningeal relationships to the cranial cavity and skull base foramina. Anatomical accuracy verified by SciePro's Medical Advisory Board.