Myotome

In vertebrate embryonic development, a myotome is a group of tissues formed from somites that develop into the body wall muscle.

Each myotome divides into a dorsal epaxial part and a ventral hypaxial part.

The epaxial muscle mass loses its segmental character to form the extensor muscles of the neck and trunk.

The myoblasts from the hypaxial division form the muscles of the thoracic and anterior abdominal walls.

The term "myotome" is also used to describe the muscles served by a single nerve. It is the motor equivalent of a dermatome.