- The skeletal muscles and bones of the body are primarily derived from the mesoderm, one of the three primary embryonic germ layers.
- During embryonic development, the mesoderm differentiates into various tissues, including the musculoskeletal system, the cardiovascular system, and the urogenital system.

- Specifically, the paraxial mesoderm segments into somites, which further differentiate into the sclerotome (forming the axial skeleton, including vertebrae and ribs) and the dermomyotome (giving rise to skeletal muscles and dermis).
- This process underscores the fundamental role of the mesoderm in establishing the structural framework of the body.

- In contrast, the ectoderm primarily forms the nervous system and skin, the endoderm gives rise to the internal lining of the digestive and respiratory systems, and the neural crest—derived from ectoderm—forms specific structures such as peripheral nerves, melanocytes, and some facial cartilage, but not the primary skeletal muscles or bones.

Key Points:
- The mesoderm is the germ layer responsible for forming skeletal muscles and bones.
- The paraxial mesoderm differentiates into somites, which generate the musculoskeletal components.
- Ectoderm and endoderm have distinct developmental fates unrelated to skeletal muscles and bones.
- The neural crest contributes to some specific structures but not to the formation of primary skeletal muscles or bones.

Reference: Sadler, T. W. *Langman’s Medical Embryology*, 14th Edition, Chapter 5: Mesoderm and Musculoskeletal Development, pp. 120-135.