Somatic muscle development

B. The Founder Cell Concept of Somatic Muscle Development... 

Figure 2. The function of tinman in the formation of mesodermal tissues. The (eft column shows wild-type embryos and the right column tinman mutant embryos of the same stage and stained with the same markers. (A, B) Neither cardioblasts nor pericardial cells are formed in tin mutants (embryos stained as in Figure 1 ). (C, D) The midgut musculature (stained for flCal expression from an enhancer trap insertion is completely m ssing in tinman mutants. (E, F Dorsal muscles (stained for [iCa expression from a .cZ reporter insertion Yin and Frasch, 1998) are not properly specified in tinman mutants. (G, H) Earlv stage 12. The muscle founders of the S59 cluster I (as detected with an S59 antibody), which give rise to muscles 5 and 25, are not specified in tinman mutants. By contrast, the founder cells of S59 cluster II are formed normally and will develop into muscles 26, 2(r, and 29, (I, J) Stage 11. huttonlesi niRN.A expression in the DM cell precursors (arrow) is absent in tin mutants and DM cells are not formed. (The bilateral pairs of nuclei are Eve-stained neuronal precursors).. Abbreviations DM dorsal median cell precursors dsm dorsal somatic muscles mgv m midgut visceral mesoderm pc pericardial precursors.

Gajewski, K., Kim, Y., Choi, C. Y, and Schulz, R. A. (1998). Combinatorial control of Drosophila mef2 gene expression in cardiac and somatic muscle cell linet es. Dev. Genes Evol. 208 382-392. Gajewski, K., Kim, Y., Lee, Y., Olson, E., and Schulz, R. (1997). D-mefi is a target for Tinman activation during Drosophila heart development. EMBO J. 16 515-522. 

Lin, S., Lin, M., Horvath, P., Reddy, K., and Storti, R. (1997). PDPl, a novel Drosophila PAR domain bZlP transcription factor expressed in developing mesoderm, endoderm and ectoderm, is a transcriptional regulator of somatic muscle genes. Development 724 4685-4696. 

Shishido, E., Ono, N., Kojima, T., and Saigo, K. (1997). Requirements of DFRl/Heartless, a mesoderm-specific Drosophila FGF-receptor. for the formation of heart, visceral and somatic muscles, and ensheathing of longitudinal axon tracts in CNS. Development 724 2119-2128. 

The muscular attachments are commonly described as bilaterally mmetric. Unfortunately, this is not the case. Everyone has asymmetric development. This causes unstable lypotonic or lypertonic muscular development. Even simple spmal motions would become imbalanced if not for the synergistic or stabilizing assistance of other groups of muscles. All motions are susceptible to dysfunction because of these factors. The greater the imbalance, the greater the tendency for the development of somatic dysfunction. 

The cervical region musculature is commonly involved in stress-related reactions. During times of stress, individuals tend to tense the neck and upper back muscles, elevate the shoulders, and as a result have pain and stiffness of the neck and upper back. Some patients tend to "carry the weight of the world on their shoulders, and the trapezius tenses. Often, tender points and trigger points develop in this muscle. Trigger points in the trapezius usually refer pain to the head. Teaching the patient techniques to cope with stress is important in the treatment of stress-related somatic dysfunctions. 

A nearly infinite number of partially close-packed positions of the wrist articulation can be created by muscle contraction and tightening of the ligaments. The close-packed articulation transmits force to the end of its total unit. Acting as a lever, it produces maximum force impact at one end, which would be the first "open pack" articulation. Somatic dysfunctions may easily develop in this manner, without sustaining direct trauma to the joint involved. 

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