The main tissue origin of skeletal muscle is which germ layer?

• A. Neural ectoderm
• B. Surface ectoderm
• C. Mesoderm
• D. Neural crest cells

Answer: (C)

Skeletal muscle comes from the mesoderm. In early development, the paraxial mesoderm forms somites, and the myotome portion of each somite differentiates into skeletal muscle precursors (myoblasts). These myoblasts proliferate and fuse to create the multinucleated muscle fibers that make up skeletal muscle in the limbs and trunk (and, in the head region, from cranial mesoderm as well). This mesodermal origin distinguishes skeletal muscle from tissues derived from other germ layers: neural ectoderm builds the brain and spinal cord; surface ectoderm forms the epidermis and related structures; neural crest cells contribute to peripheral nerves and many craniofacial tissues but not the main source of skeletal muscle.