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biomedicalephemera:

Our Three (Brain) Mothers

Protecting our brain and central nervous system are the meninges, derived from the Greek term for “membrane”. You may have heard of meningitis - this is when the innermost layer of the meninges swells, often due to infection, and can cause nerve or brain damage, and sometimes death.

There are three meningeal layers: the dura mater, arachnoid mater, and pia mater. In Latin, “mater” means “mother”. The term comes from the enveloping nature of these membranes, but we later learned how apt it was, because of how protective and essential the meningeal layers are.

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  • The dura mater is the outermost and toughest membrane. Its name means “tough mother”.

The dura is most important for keeping cerebrospinal fluid where it belongs, and for allowing the safe transport of blood to and from the brain. This layer is also water-tight - if it weren’t, our cerebrospinal fluid (CSF) would leak out, and our central nervous system would have no cushion! Its leathery qualities mean that even when the skull is broken, more often than not, the dura (and the brain it encases) is not punctured.

  • The arachnoid mater is the middle membrane. Its name means "spider-like mother", because of its web-like nature.

The arachnoid is attached directly to the deep side of the dura, and has small protrusions into the sinuses within the dura, which allows for CSF to return to the bloodstream and not become stagnant. It also has very fine, web-like projections downward, which attach to the pia mater. However, it doesn’t contact the pia mater in the same way as the dura: the CSF flows between the two meningeal layers, in the subarachnoid space. The major superficial blood vessels are on top of the arachnoid, and below the dura.

  • Pia mater is the innermost membrane, which follows the folds (sulci) of the brain and spinal cord most closely. Its name means “tender mother”.

The pia is what makes sure the CSF stays between the meninges, and doesn’t just get absorbed into the brain or spinal cord. It also allows for new CSF from the ventricles to be shunted into the subarachnoid space, and provides pathways for blood vessels to nourish the brain. While the pia mater is very thin, it is water-tight, just like the dura mater. The pia is also the primary blood-brain barrier, making sure that no plasma proteins or organic molecules penetrate into the CSF. 

Because of this barrier, medications which need to reach the brain or meninges must be administered directly into the CSF.

Images:
Anatomy: Practical and Surgical. Henry Gray, 1909.

cross-connect:

The Godlike Mythological and Geometric Paintings of Miriam Escofet

My ‘arrival’ at painting has been a slightly unusual one, in the sense that I purposely set out to study a skills based 3D Design course, where I specialized in ceramics. My rationale for this being that I have always loved the ‘making process’ and I am very interested in the three dimensional and textural quality of objects and spaces. I worked in clay for some years after leaving Art College, whilst starting to get commissions for paintings (mainly watercolours at the time). The painting evolved from this  and eventually took up all my time. Drawing and making are still at the core of the work, but painting allows me to invent other spaces and ideas with no physical constraints.

Thanks to Hi-Fructose Magazine for the find

I must be willing to give up what I am in order to become what I will be.

—Albert Einstein (via purplebuddhaproject)

theolduvaigorge:

Skulls in Print: Scientific Racism in the Transatlantic World

  • from Past Horizons

mummified corpse. An embalmed head. A neat bullet hole in the side of a skull. These are just some of the 78 disturbing illustrations which make up Samuel George Morton’s Crania Americana, undoubtedly the most important work in the history of scientific racism.

Published in Philadelphia in 1839, Morton divided mankind into five races before linking the character of each race to skull configuration. In a claim typical of the developing racial sciences, Morton wrote of Native Americans that “the structure of his mind appears to be different from that of the white man”. Within a few years Crania Americana had been read in Britain, France, Germany, Russia and India. James Cowles Prichard, the founding father of British anthropology, described it as “exemplary” whilst Charles Darwin considered Morton an “authority” on the subject of race. Later in the nineteenth century, other European scholars produced imitations with titles including Crania Britannica and Crania Germanica.

James Poskett, from the Department of History and Philosophy of Science, is working to uncover how Crania Americana became so influential, not only in the United States, but in Europe and beyond. He has also curated a new exhibition for readers at the Whipple Library charting this history. The showpiece is undoubtedly a copy of Crania Americana itself. The book is extremely rare. Only 500 copies were ever printed with no more than 60 being sent outside of the United States. “This research is crucial for understanding how racist theories gain credibility,” said Poskett. “Particularly in the early nineteenth century, European scholars tended to treat American science with suspicion. Morton had to work hard to convince his peers across the Atlantic that Crania Americana should be taken seriously.”

Establishing a reputation

The illustrations, now on display at the Whipple Library helped Morton establish his reputation in Europe. Reviewers in Britain were astounded by the eerie, life-like quality of the skulls. To create such an effect, Morton’s artist, John Collins, used a new technique called lithography. He first drew each image onto a limestone block in wax before fixing, inking and printing. The limestone allowed Collins to create fine-grained textures, reproducing the subtle contours of each skull in Morton’s collection” (read more).

(Source: Past Horizons)

(via scientificillustration)