This is clipart converted and broken apart that has been released into the public domain because the document says so, and its from NASA, a USA government agency. The publication is called "The Brain in Space:" http://www.nasa.gov/audience/foreducators/topnav/materials/listbytype/The.Brain.in.Space.html
聽診器平原
astronomy、brain、converted、doctor、government、hospital、nasa、science、space、stethoscope、usa
天文學、腦、轉換、醫生、政府、醫院、上、科學、空間、聽筒、使用
資料來源：openclipart ( https://openclipart.org/ )