So here's a dirty little secret. The muscle names provided in the slideshow anatomical primer are derived from the names used by medical doctors. These are the names that most people ar familiar with, especially if you have taken an anatomy & physiology course. Even if you hang out with weightlifters, you've probably heard them refer to their latissimus dorsi or trapezius muscles.
Because animal body plans are usually very different from ours, it isn't always easy to tell if our muscles are the ssame, or slightly different. And there are inportant differences. For example, there are two sets of pectoralis muscles in humans, the pectoralis major and the pectoralis minor. It may seem obvious that the pectoralis major is the larger of the two, and that's true, as long as you are looking at a higher primate. If you look at cat muscles, the pectoralis minor is larger than the p. major. Since there are important differences, and because muscle systems have been studied since before it was known that animals evolve from one another, early biologists simply came up with their own muscle nomenclature for different groups of animals, whenever it was convenient.
You might wonder that since we know better now, couldn't we just use one set of names for te muscles of all animals (or at least all vertebrates)? Sadly, there are still important differences in musculature between animal groups. Birds have evolved some muscles that mammals don't have, and vice versa. A biologist only wants to only want to use the same name for two different muscles if they are the same in an evolutionary sense; if they are homologous. When the section on evolutionary concepts is done, there will be a section on homology vs. analogy. In the mean time, link to the glossary for an introduction.
The take home message here is that there ar real problems figuring out if the muscles of two different animals are really the same muscles. For this reason, scientists generally would not publish a paper on dinosaurs that uses human anatomical terms. Instead, they usually use the nomenclature for either crocodiles or birds. There has been a trend lately to use the names of bird muscles, as defined by the Handbook of Avian Anatomy: Nomina Anatomic Avium.
It is easier for many people to leanr the human anatomy terms, and if it's easier for you, that's ok. Just remember that they aren't the official names for dinosaur muscles. For everyone who would like to learn them using avian muscle nomenclature, I've provided a link below. Feel free to compare the human and avian names of the muscles using the links below. I will be posting close-ups of more parts of the body, as well as a self-test, for those who really want to commit the terms to memory.