Somites are transient segmented structures derived from paraxial mesoderm. contain the progenitors of the axial skeleton, trunk musculature and associated tendons, trunk dermis, endothelial cells, and meninges of the spinal cord

ventromedial part of the somite forms the sclerotome the remainder of the somite consists of a dorsal epithelial layer called the dermomyotome dermomyotome quickly separates into two structures: a dermatome and a myotome The dermatomes contribute to the dermis (including fat and connective tissue) of the neck and the back.

The myotomes differentiate into myogenic (muscle-producing) cells Each myotome splits into two structures: a dorsal epimere and a ventral hypomere The epimeres give rise to the deep epaxial muscles of the back, including the erector spinae and transversospinalis groups.

The hypomeres form the hypaxial muscles of the lateral and ventral body wall in the thorax and abdomen [intercostal muscles,external oblique, internal oblique, and transversus abdominis, and the rectus abdominis]

Cervical region:hypaxial myoblasts form the strap muscles of the neck, including the scalene and infrahyoid muscles. Lumbar region, the hypomeres form the quadratus lumborum muscles. At limb-forming levels, hypaxial myoblasts invade the developing limb buds and give rise to the limb musculature.