Myotomal

Myotomal refers to the group of muscles in a vertebrate embryo that are derived from a single somite. Somites are segmented blocks of mesoderm that form along the neural tube during early development. As the embryo grows, these somites differentiate into three distinct parts: the sclerotome, the myotome, and the dermatome. The myotome is specifically the part that gives rise to skeletal muscles.

The myotome further divides into two populations of cells: the epimere and the hypomere. The epimere cells migrate dorsally to form the intrinsic muscles of the back, which are responsible for movements like extending and rotating the spine. The hypomere cells migrate ventrally and laterally to form the muscles of the limbs and the body wall. Therefore, the muscles of the trunk and limbs are organized according to their embryonic origin from specific myotomes.

The pattern of muscle development from myotomes is remarkably conserved across different vertebrate species, reflecting a shared evolutionary history. Understanding myotomal organization is crucial for studying muscle development, congenital muscle disorders, and the evolutionary relationships between different animal groups. Injury or developmental abnormalities affecting a specific myotome can lead to characteristic patterns of muscle weakness or paralysis.