MUSCLES AND TENDONS Cardiac muscle A transmission electron micrograph showing a longitudinal section of cardiac (heart) muscle, in which the sarcomere structure and a large intercalated disc can be seen. Credit: Professor Giorgio Gabella, Wellcome Images Relaxed skeletal muscle A colour-enhanced transmission electron micrograph of myofibrils in an uncontracted skeletal muscle cell (muscle fibre), showing the structure of the sarcomere with its dark and light bands between the two Z-discs. Credit: University of Edinburgh, Wellcome Images BIGPICTUREEDUCATION.COM Striated muscle A light micrograph of a stained longitudinal section through striated muscle. Credit: Spike Walker, Wellcome Images BIGPICTUREEDUCATION.COM Glycogen stored in muscle A transmission electron micrograph showing glycogen storage in a muscle cell. Some glycogen granules are dispersed around the many mitochondria in between the contractile myofibrils, but most of the glycogen is in a large area at the edge of the cell. Credit: Mike Kayser, Wellcome Images BIGPICTUREEDUCATION.COM Historical experiments on frog nerves Galvani’s experiments on the sciatic nerve of frogs. This was the first detection of galvanic currents. From ‘Memorie sulla elettricita animale’ by Luigi Galvani (Bologna, 1797). Credit: Wellcome Library, London BIGPICTUREEDUCATION.COM Muscle cross-section A cross-section diagram of a muscle, showing fibres. Credit: Miles Kelly Art Library, Wellcome Images BIGPICTUREEDUCATION.COM Ruptured tendon A confocal image showing damaged collagen fibres in a ruptured tendon. The area of wavy fibres to the lower right shows the normal, healthy appearance of a tendon. The waviness allows the whole tendon to have a small amount of elasticity (between 2 and 10 per cent); the collagen fibres themselves do not stretch. Credit: Martin Knight, Wellcome Images BIGPICTUREEDUCATION.COM Reusing our images Images and illustrations • All images, unless otherwise indicated, are from Wellcome Images. • Contemporary images are free to use for educational purposes (they have a Creative Commons Attribution, Non-commercial, No derivatives licence). Please make sure you credit them as we have done on the site; the format is ‘Creator’s name, Wellcome Images’. • Historical images have a Creative Commons Attribution 4.0 licence: they’re free to use in any way as long as they’re credited to ‘Wellcome Library, London’. • Flickr images that we have used have a Creative Commons Attribution 4.0 licence, meaning we – and you – are free to use in any way as long as the original owner is credited. • Cartoon illustrations are © Glen McBeth. We commission Glen to produce these illustrations for ‘Big Picture’. He is happy for teachers and students to use his illustrations in a classroom setting, but for other uses, permission must be sought. • We source other images from photo libraries such as Science Photo Library, Corbis and iStock and will acknowledge in an image’s credit if this is the case. We do not hold the rights to these images, so if you would like to reproduce them, you will need to contact the photo library directly. • If you’re unsure about whether you can use or republish a piece of content, just get in touch with us at bigpicture@wellcome.ac.uk.