#arahnoid

• Arachnoid mater — An alternative medical or Latin spelling variant for arahnoidă (arachnoid mater); the middle, thin, and avascular meningeal membrane situated between the dura mater and pia mater, surrounding the brain and spinal cord. Its name derives from its fine, reticular structure resembling a spider's web, playing a crucial physiological role in defining the subarachnoid space through which cerebrospinal fluid circulates.
• Arachnoid — Resembling a spider web in fineness, structure, or network of filaments; arachnoidal. In human and animal anatomy, the term describes delicate meningeal elements or membranes, whereas in zoology it is rarely used as a noun to denote a member of the arachnid class or a morphological feature reminiscent of the order of spiders.
• Arachnoid mater — The middle meningeal membrane, thin, transparent, and completely avascular, situated between the dura mater (externally) and pia mater (internally), surrounding and protecting the brain and spinal cord. It is characterized by a fine reticular structure reminiscent of a spider web and plays a crucial physiological role in defining the subarachnoid space through which cerebrospinal fluid circulates and resorbs.
• Arachnoid variant — An archaic or unconventional spelling and morphological variant for arahnoid or arahnoidian, historically used in 19th-century Romanian medical literature to describe a fine structure resembling a spiderweb. The term was formed through direct borrowing of the older French adjectival form, being completely replaced in the modern academic lexicon by standardized terms.
• Arachnoidal — Pertaining to the arachnoid mater; relating to or located at the level of the middle meningeal membrane of the brain. In clinical medicine and semiology, the term describes anatomical spaces, cysts, hemorrhages, or vascular structures localized in the immediate vicinity of this fine reticular network surrounding the cerebrospinal axis.
• Arachnoiditis — A progressive neurological disorder characterized by the chronic inflammation of the arachnoid mater, the middle meningeal membrane surrounding the brain and spinal cord. This pathology leads to the development of scar tissue and fibrous adhesions that can trap and compress spinal nerve roots, causing severe chronic pain, numbness, muscle spasms, and motor impairments, often triggered by infections, spinal surgeries, or irritating chemical substances.