Cross-sectional Human Anatomy: An Adjunct to Medical Student Gross Anatomy

	David Dean1 and Thomas Herbener2 Department of Anatomy1 Department of Radiology2 Case Western Reserve University 10900 Euclid Avenue Cleveland, OH 44106

THE NEED We estimate that cross-sectional images comprise 5-15% of medical school gross anatomy practical exam material nationwide. These test materials, in most cases, are band-sawed slices of a locally obtained cadaver encased in Lucite. Very often students receive no explanation as to how these images correspond to clinical radiographic imagery. Indeed, in many cases anatomical section images, as a whole, are left out of lectures and dissection laboratory exercises preceding the practical exam. This situation is due to a lack of textual reference and other materials for lecture presentation and home study. How do students learn this material? Unfortunately, the most common experience is one of memorizing all the labels found on the Lucite blocks whose distribution is usually limited to the formaldehyde-rich cadaver lab wall. When students leave this memorization exercise to the last moment there is crowding around these scarce images. This adds to the trauma of this memorization exercise. Unlike the era when most band-sawed cadaver sections were mounted in dissection labs, viewing the anatomy in section is no longer merely a test of the students ability to visualize structure. Following first and/or second year anatomy, medical students encounter cross-sectional radiographic images, especially CT and MR, as soon as they begin their 3rd and 4th year clinical rotations. This involvement continues for most through residency and practice. The primary goal of the proposed atlas is to allow the introductory medical school anatomy student to develop sufficient comfort with cross- sectional images that they are able to identify a sizable number of clinically significant structures. This atlas is not intended to add vast tracts of new material to the basic gross anatomy course. The idea for such a complementary atlas is not completely novel.

CURRENT ATLASES Several atlases of human cross-sectional and radiographic anatomy already exist. Most of these present nearly colorless, band-sawed, cadaver images and roughly correlated radiological images obtained from the local medical records office. The quality of the radiographic images is often well below what is possible. These texts have uniformly been poor market performers. The National Library of Medicine's recently released Visible Human image collection presents high contrast images with virtually in vivo tissue colors. These cross-sectional tissue images are nearly perfectly correlated to a set of high resolution radiographic CT and MR grayscale images. The entire set of images are currently available, in heavily subsampled (low resolution) format, from several vendors. However, sorting through these thousands of images for relevant structures is a daunting task for first and second year medical students. It is our estimate that 175-200 images would best present all of the structures necessary for these students as well as those preparing for 4th year USMLE and many residency board exams. AN INTEGRATED APPROACH We are preparing a print atlas of approximately 200 Visible Human cross-sectional images, to be accompanied by 35mm slides, and sturdy, high resolution acetate covered pictures for study, lecture, and exam use. The key to integrating this material into medical student gross anatomy will be faculty cross-reference of these images as used in: lecture, laboratory dissection, and home study materials. ACKNOWLEDGEMENTS The development of the "Cross-sectional Human Anatomy Atlas" proposal was supported by the Departments of Anatomy and Radiology, School of Medicine, Case Western Reserve University.