Page 35 - 16_Atti_SNO_2022_flip

Proceedings SNO “LXI Congresso Nazionale SNO”

GOVERT BIDLOO (1649-1713) noted the presence of
the arachnoid membrane peeling away the coverings
of the brain, from the scalp to the layers of the
meninges, in order to prepare for dissection of the
brain (Figure 10).
HUMPHREY RIDLEY (1653-1708) gave a thorough de-
scription of the arachnoid membrane and describes it
in 1695 using the term “meninx arachnoidea”. He
had demonstrated a retiform membrane that spanned
the cortical gyri and he described that the membrane
as a separate layer invested cerebral vessels and in-
tracranial nerves, the first description of the concept
of subarachnoid cisterns.
One of the most elegant and accurate descriptions of
the arachnoid membrane was provided by ALBRECHT
VON HALLER (1708-1777) in his book Bibliotheca
Anatomica published in 1774: “Pellucid as water,
very thin, and as far as its thinness permits, firm, it
completely envelopes the brain, passing over its larg-
er and smaller furrows, and inclosing the larger ves-
sels, so that they lie between the arachnoides and pia
mater”.
XAVIER BICHAT (1771-1802) presented in his Traité
des membranes published in 1800 the first detailed Figura 11. From Key and Retzius, Studien in der Anatomie
study of the arachnoid membrane and he described des Nervensystems und des Bindegewebes, 1875.
the concept of the subarachnoid cistern and he no-
ticed that the arachnoid membrane is a “serous mem-
brane” covered cerebral vessels and cranial nerves.
As Bichat mentioned, the triple covering of the brain
has not always been clearly described by anatomists.
ERNST AXEL HENDRIK KEY (1832-1901) and GUSTAV
MAGNUS RETZIUS (1842-1919) published their land-
mark contribution in 1875, the first work on the
anatomy of subarachnoid cisterns, describing the
arachnoid and cisterns with stunning color plates.
They described in detail all layers of the meninges
with particular regard to the arachnoid and granula-
tions arising from the arachnoid membrane and pro-
jecting into the subdural space. They demonstrated
the extensions and divisions of the subarachnoid sys-
tem with injection of blue dye concluding that the
substance of the arachnoid consists of fibrillary bun-
dles that form a network of irregular meshes (Figure
11).
The importance of these findings had to await the in- Figura 12. From Ya argil, Microneurosurgery, 1984.
troduction of the operating microscope in neuro-
surgery. MAHMUT GAZI YA ARGIL (1925-) in 1976
published the first description of the microsurgical plorations under the operating microscope focused
anatomy of the subarachnoid cisterns. Subarachnoid on the concept of neurosurgery in terms of moving
cisterns and their contents are described briefly in the from one cistern to another, the arachnoidal surgical
light of observations made during microsurgical ex- approach (Figure 12).

- 33 -