Bell, Charles: The anatomy of the brain: explained in a series of engravings (London, 1802)

55

EXPLANATION

OF

PLATE IX.

THIS, like the last Plate, is a partial view enlarged to the natural
size, so as to enable us to represent the Nates and Testes, the Pineal
Gland, the Iter ad quartum Ventriculum, the fourth
Ventricle, the Valvula Vieussenii, and the Arbor Vitm,
more minutely by a perpendicular section.

a. The Sphenoid Bone, where it lies before the Pons Varolii.

b. The Third Ventricle

c. A Probe introduced into the Iter ad quartum Ventriculum 2,

which we see passes down before the Nates and Testes, Posterior
Comissure, and Pineal Gland.

d. The Pineal Gland.

1 Ventricle of the Thalami Nervorum Opticorum—Rima longa—Ventriculus Com-
munis. " Ventriculus tertius infra psalterium excavatus abeoq; plexu Choroideo
" separatus, infra Thalamos opticos situs, nullum firme occupat spatium." Massa.
Tarin.

2 " Hiatus ad canalem natibus et testibus substratum ducens." Vieussens. Aquae
emissaria aqua?-ductus Silvii.—Hasius.