Morphogenesis and Morphology of the Neck and Trunk Muscles in Humans

At about the 20-30 day of embryonic life "Somites" start to appear. In the middle of the fourth week the dorsal portion of each Somite differentiates into an epithelially­arranged mass of cells called der­momyotome (from which the skin and mus­cles originate).  The lateral part of the sermomyotome then proliferates to form dermatome (from ·which originates the derm and Hypoderm).  The medial part of the dermomyotome proliferates to form myotome (which gives origin to muscles).  At the end of the fifth week of embryonic life, myotomes divide into the dorsal por­tion, called Epimere and the ventral por­tion, called Hypomere.  The spinal nerve of each myotome di­vides in to the posterior primary Ramus, with which the Epimeric muscles are sup­plied and the Anterior Primary Ramus, with which Hypomeric muscles are sup­plied.  In this article, the development of Cervi­cal, Thoracic, Lumbar, Sacral, and Coc­cygeal myotome and their division into Epimeric and Hypomeric portions, as well as the muscles to which they give rise and their synonymities are discussed.  In my opinion, the study of synonymities in different layers of muscles in the neck and trunk could explain most of muscular and neural reff erral pains .