What body systems does meningitis affect?
There are three meninges surrounding brain and spinal cord:
from top to bottom:
1. dura mater
2. arachnoidal mater
3. arachnoidal space (not the actual meninge, rather space filled with CSF)
4. pia mater
Arachnoidal space is just a space between two meninges (dura and pia mater) filled with cerebrospinal fluid (CSF).
Arachnoidal space and pia mater are usually referred as leptomeninges.