Show both caption AND description of a picture on pages/posts. http://wordpress.stackexchange.com/questions/48117/how-to-show-description-under-an-inserted-image (Third suggestion from Kovah)

show-description.php

add_shortcode('wp_caption', 'img_caption_add_description');
add_shortcode('caption', 'img_caption_add_description');
function img_caption_add_description($attr, $content = null)
{
    $post_id = str_replace('attachment_', '', $attr['id']);
    $img = get_post((int)$post_id);

    if (is_a($img, 'WP_Post')) {
        $attr['caption'] = $img->post_content;
    }

    return img_caption_shortcode($attr, $content);
}