ICU3 - Cross Sectional Anatomy - 2011
This practical is intended to complement your dissection work. Try to relate the two.
Modern diagnoses are often based on cross sectional images: CT, MRI or ultrasound. It is important to be able to convert readily from cross sections to three-dimensional images and to recognise anatomical structures viewed from a variety of orientations.
The full instructions at http://www.bmb.leeds.ac.uk/teaching/icu3/practic/comp/index.htm include Guided Tours and a Revision Checklist with clickable links to labelled sections showing all the key anatomical features. There are some practice exam questions and self assessment tests at the end of these instructions.
The images are on two websites with very different features. Be sure to visit both of them.
1) “Visible Human” images at http://www.bmb.leeds.ac.uk/illingworth/visible/vismale.htm on the BMB server. The freshly frozen healthy male cadaver came from a judicial execution in Texas. These sections are 1mm thick, and can be viewed at low or high resolution.
2) CT scans at: http://www.bmb.leeds.ac.uk/illingworth/visible/xrays.htm The sections for these greyscale images of a healthy female are 10mm thick. The subject was given intravenous X-ray contrast medium, which was filtered by her kidneys, revealing her urinary tract. Note the peristalsis in the ureters, and the boluses of urine moving towards her bladder. Iodine-based contrast medium is much denser than water and has settled in her bladder. She also drank some X-ray contrast medium, which outlines the lumen of her upper GI tract. Make sure that you can recognise the major anatomical structures on these X-ray images.
All these images are viewed looking from the feet towards the head. This is the international standard for cross sectional x-ray images. It is the way a doctor would normally view a patient in bed, but the opposite orientation to the way that you probably think about your own body. Notice the conspicuous LEFT and RIGHT marked on each image.
Both sites have some features in common:
a) Click the HEAD and FEET buttons to move one section at a time cranially or caudally. Double click to jump ten sections at a time on the “Visible Human”. This is unnecessary on the X-ray images where the sections are already ten times thicker.
b) Each site includes an image map viewed at right angles to the main sections. Scroll down to see these image maps. Click in the image map to jump directly to the corresponding section. The “box” on the CT scans provides a lower exposure setting for the lungs.
c) You can also jump directly to a specified section. Click the JUMP button, enter the desired number in the section number window then press RETURN.
d) Click the MORE button on the Visible Human images to switch to a higher resolution image which more than fills the screen. You must use the scroll bars to inspect this image, but you can still use the HEAD, FEET and JUMP buttons to move between sections. Click the LESS button to return to the low resolution dataset. The MORE button doesn’t work on the X-ray images.