By MIKA ROSS-SOUTHALL
Drilling into a human skull and operating on a brain requires, I hope, a lot of training. But how do neurosurgeons practise, or even experiment? I ducked into a fascinating exhibition at the Hunterian Museum on Lincoln’s Inn Fields recently which shows how 3-D models of human anatomy are meticulously made for this very purpose. For trainee surgeons hands-on interaction, as well as theory, is crucial.
It seems simple enough to build a scale model of a head – what’s not simple is getting it to feel like one. The focus of Designing Bodies (running until February 20) is on the MARTYN (Modelled Anatomical Replica for Training Young Neurosurgeons; picture above), developed over the past four years by a surgeon and an artist, with the help of the Hunterian (which is part of the Royal College of Surgeons). Despite the sterile, gleaming display cabinets, the MARTYN looks like an almost primitive artwork: it’s split into five main components, one being the skull which is cast in polyurethane resin. On display, though, the mould from which the skull is cast is like any other found in a sculptor’s studio – bits of wood screwed together around clay or silicone (the use of digital technology now, i.e. 3-D printing, only means that the mould is built more accurately more quickly from a print-out, rather than by hand). Muscle components are made from silicone; the brain from a special gelatin mixture. Then we come across ventricles, the fluid-filled cavities within the brain (sliced in two here, they appear buttery, cloying; the right texture); and finally the dura mater, a membrane which surrounds the brain, recreated from latex.
Other simulated “features” created for the MARTYN include tumours and drainable fluid from the brain. A photograph, taken last year at Imperial College, presents a robot performing keyhole surgery on a MARTYN “featuring a model aneurysm in the circle of Willis”. (Is it just me, or is some of the gallery’s wording darkly comic?)
Not only are materials tested – with scientific precision, of course – for their likeness of feel to the real thing (a cabinet is devoted to a few of those that didn’t work: casting the ventricles in ice seems an obvious error to me, not least in terms of durability; for the dura mater, rice paper turned out to be “ideal when wet but too crisp when dry”), they need to look right, too. Different shades of red dye – used to mimic blood clots – are tried out, for example, on circular swatches.
Going back fifty or so years, the exhibition turns to a Royal College anatomist David Hugh Tompsett, who pushed the boundaries of “corrosion casting”. Injecting a new type of liquid resin into prepared dead organs and body parts, Tompsett would then dissolve away any remaining tissue with hydrochloric acid to reveal the intricate paths the resin had filled – blood vessels and airflows. He would prune and sculpt his corrosion casts like a bonsai tree with metal tools to highlight different areas for surgeons to look at. A delicate cream, alien-looking bronchial tree from the 1950s sits alongside more elaborate multi-coloured corrosion casts of heart and brain vessels. I wonder if the sculptors Helen Chadwick, with her “Piss Flowers” (casts of urine in snow), or Rachel Whiteread (who fills the insides of everyday objects – doors, boxes, sheds, houses – in resin) ever saw Tompsett’s models.
Over in another corner of the gallery, we find the orthopaedic surgeon John Herbert Hicks’s wooden “joint” models – of knees, ankles and so on, during the 1950s and 60s. He recorded how his models moved in a black-and-white photoseries, similar to Eadweard Muybridge’s photographs of motion. “It is difficult to visualize but the model will help”, Hicks told his students in 1955. “To overcome the difficulties of a description confined to the two dimensions of this page the reader if he wishes to be convinced of the essential simplicity of all this must make for himself the cardboard model illustrated.” And, sure enough, the Hunterian provides a piece of cardboard, with perforated push-out sections, for us to take away and make our own 3-D ankle-joint model at home, just like Hicks’s. Surprisingly challenging (at least for this visitor).