I'm not sure if anyone would be willing to send you their essay outright (I'm not), but I can offer a bullet point summary of mine. Each bullet point roughly corresponds to one paragraph.
- Outline, as I see them, the contrasting demands on an MD and PhD student, and likewise those on a clinician and scientist. Explain why carving out the niche between them is important and why I would like to train to enter that intersection.
- Briefly outline some reasons why I am a fit candidate for the MD/PhD program but more importantly for the role of a physician-scientist. Provide 3-4 short examples of experiences/skills I have that demonstrate I can meet the demands listed in the previous bullet point.
- Give a few reasons why both degrees in combination will help me achieve my specific career goals (and obviously, summarize those goals and/or remind the reader of them from other essays). With my specific interests in computational processing and analysis of neural signals, stress that the quantitative rigor of the PhD program will enable me to pursue difficult translational research questions whose answers can manifest into new clinical therapies.
- Finally, explain that my passion for face-to-face interaction and interpersonal service drives me towards medicine, and that research alone would not fulfill this motivation.
Looking over my essay now, it was fairly broad in scope, but I provided 5 distinct examples (concisely) that referenced other parts of my application package and that tied together the threads of MD and PhD. General is fine, but I believe you have to provide concrete justifications and examples to convince adcoms.