Musculature

Striated muscles

Skeletal muscles. Following migration of sclerotomic cells, the somites are transformed into dermomyotomes. The promyoblasts (muscle progenitor cells) of the dermomyotome differentiate into myoblasts in the 4 to 5 week old embryo. At about week 6, a group of myoblasts forms the myotome in the centre of the former somites, which gives rise to the epaxial muscles (muscles of the back). Another group of myoblasts migrates from the somites towards the lateral aspects of the embryo. This is the site of formation for the muscles of the limbs, shoulder and hip girdle and of the body wall (hypaxial muscles).