BIOL 030 Lecture Notes - Lecture 20: Myogenesis, Myod, Anterior Ramus Of Spinal Nerve
16 Sep 2020
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Myod & myf5 continue to influence myotome. Induce specification to myogenic fate (this is already accomplished) Promote fusion of myogenic cells to form muscle fibers. Direct the organization of contractile proteins within the maturing muscle fibers. Somites in different rostro-caudal levels form appropriate muscle groups. Limb buds form from mesenchyme overlain by ectodermal tissue. Limb muscles form from the lateral portions of limb level somites, specifically the hypaxial area. These differentiate into myoblasts and then myotubules. Upper limb buds form around day 24 from c5-t1 somites. Lower limb buds form around day 28 from l2-s3 somites. Within a limb bud the myoblasts form two masses. Dorsal limb bud mass forms all limb extensor muscles (upper limb suppinators, all lower limb abductors) Innervated by dorsal branch of ventral rami. Ventral limb bud mass forms all limb flexor muscles (upper limb pronators, lower limb adductors) Limb bud masses eventually split to form specific muscles.
