|Scheme showing the manner in which each vertebral centrum is developed from portions of two adjacent segments. (Myotome labeled in upper right.)|
|Transverse section of a human embryo of the third week to show the differentiation of the primitive segment. ao. Aorta. m.p. Muscle-plate. n.c. Neural canal. sc. Sclerotome. s.p. cutis-plate. ("Muscle-plate" is an older term for "myotome.")|
|Gray's||subject #17 80|
|Gives rise to||muscle|
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.