As you can see from the diagram horse and human muscles are not so very different.  A horse is basically like a human folded forward!

1. Masseter Muscle
2. Sternocleidomastoideus Muscle
3. Trapezius Muscle
4. Latissimus dorsi muscle
5. Gluteal
6. Biceps femoris muscle
7. Triceps surae muscle
8. Achilles tendon
9. Quadriceps femoris muscle
10. Obliquus externus abdominis muscle
11. Pectoralis muscles
12. Triceps brachii muscle
13. Biceps brachii or brachialis horse muscle
14. Deltoideus muscle