arachnoid mater
Pronunciation: ah-RACK-noid MAY-ter
The middle layer of the three meninges covering the brain and spinal cord, resembling a spider web in structure.
Full Definition
The arachnoid mater is the middle meningeal layer situated between the dura mater (outer layer) and pia mater (inner layer) that protects the brain and spinal cord. Named for its web-like appearance, this delicate membrane contains cerebrospinal fluid in the subarachnoid space beneath it. The arachnoid plays crucial roles in cerebrospinal fluid circulation and brain protection. Medical editors frequently encounter this term in neurosurgical reports, neuroanatomical descriptions, and documentation of meningeal pathology. Arachnoid cysts, arachnoid granulations, and subarachnoid hemorrhage are common clinical conditions involving this structure. Understanding meningeal anatomy is essential for interpreting neurological procedures and pathological findings. The arachnoid's barrier function helps maintain the brain's chemical environment.
Usage
Usage note: Middle meningeal layer; important in neurosurgical anatomy and pathology.
In Context
- "Surgical dissection revealed thickened arachnoid mater consistent with chronic inflammation." — Neurosurgical operative report
- "Arachnoid mater appeared intact during the craniotomy procedure." — Intraoperative documentation