From Embryology

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Fig. 769. Diagrammatic representation of a section across the top of the skull

Showing the membranes of the brain, etc. (Modified from Testut.)

The Arachnoid Villi (granulationes arachnoideales; glandulæ Pacchioni; Pacchionian bodies) (Fig. 769) are small, fleshy-looking elevations, usually collected into clusters of variable size, which are present upon the outer surface of the dura mater, in the vicinity of the superior sagittal sinus, and in some other situations. Upon laying open the sagittal sinus and the venous lacunæ on either side of it villi will be found protruding into its interior. They are not seen in infancy, and very rarely until the third year. They are usually found after the seventh year; and from this period they increase in number and size as age advances. They are not glandular in structure, but are enlarged normal villi of the arachnoid. As they grow they push the thinned dura mater before them, and cause absorption of the bone from pressure, and so produce the pits or depressions on the inner wall of the calvarium.

(text modified from Gray's Anatomy)

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Gray H. Anatomy of the human body. (1918) Philadelphia: Lea & Febiger.

Cite this page: Hill, M.A. (2024, May 23) Embryology Gray0769.jpg. Retrieved from

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