In about 131 AD, who was the Roman that built a great reputation for himself by writing extensively on anatomy, physiology, and practical medicine?

The Roman who built a great reputation for himself by writing extensively on anatomy, physiology, and practical medicine in around 131 AD is Galen. He was a prominent physician and philosopher whose work laid the foundations for medical knowledge in the Western world for many centuries. Galen's contributions were significant in understanding the human body, and he conducted a variety of anatomical studies, often using animal dissections to draw conclusions about human anatomy. His writings synthesized previous medical texts and included detailed observations on the functions of different organ systems, the importance of the pulse, and the relationship between various bodily fluids.

In contrast, while Hippocrates is often referred to as the "Father of Medicine" and did contribute to the understanding of medical ethics and practice, he lived earlier than Galen and primarily focused on clinical observation and the Hippocratic Corpus. Pliny the Elder was known for his work in natural history, documenting various aspects of the natural world rather than focusing solely on medicine. Claudius Ptolemy was an astronomer and mathematician, whose work did not focus on anatomy or medicine but rather on the geocentric model of the universe and contributions to astronomy and geography. Galen stands out with his specific contributions to medicine during his time.