Subaraknoidala

Subaraknoidala, commonly referred to as the subarachnoid space, is the fluid-filled space between the arachnoid mater and the pia mater that surrounds the brain and spinal cord. It forms a continuous compartment that extends over the cerebral hemispheres, brainstem, and spinal cord, and it is traversed by delicate arachnoid trabeculae. The space contains cerebrospinal fluid (CSF) and major arteries and veins of the brain, which run within the CSF-filled interval.

Anatomically, the subarachnoid space is bounded externally by the arachnoid mater and internally by the pia mater. It communicates with the ventricular system through openings in the fourth ventricle, notably the foramina of Luschka (lateral apertures) and Magendie (medial aperture). In the cranial cavity, the space includes cisterns such as the cisterna magna (marginal, cerebellopontine), interpeduncular cistern, and chiasmatic cistern, which serve as dilated reservoirs for CSF. In the spinal canal, the subarachnoid space surrounds the spinal cord down to the cauda equina and is continuous with cranial CSF pathways.

CSF dynamics are central to the function of the subarachnoid space. CSF is produced mainly by the choroid plexus within the ventricles, circulates through the ventricular system, enters the subarachnoid space via the fourth ventricle, and is eventually absorbed into venous blood through arachnoid granulations located primarily in the superior sagittal sinus. This circulation helps cushion the brain, remove waste, and maintain homeostasis of the CNS environment.

Clinical relevance includes subarachnoid hemorrhage from ruptured aneurysms or trauma, presenting with sudden severe headache and neck stiffness, as well as infectious or inflammatory conditions such as meningitis. Diagnosis and management focus on CSF analysis, imaging, and intervention to control intrathecal pressure and vascular sources.