CDC/Doug Jordan
NLM’s Digital Collections allow searching and browsing numerous document collections: Images from the History of Medicine, World War 1, Medicine in the Americas 1610-1920, and many more. You can also search the collections for only images.
Open-i Biomedical image search engine from the National Library of Medicine that searches images from PubMed Central articles and other special image collections
Source: List of resources adapted from Touro University's Educational Tools for Your Classroom: Find Media to Use