â¢ In grade 4 mathematics, seven of the 50 states included in the analysis set standards for proficiency (as measured on the NAEP scale) that were lower than the Basic performance on NAEP, 42 were in the NAEP Basic range, and one in the Proficient range. In grade 8 mathematics, 12 of 49 states included in the analysis
noun, plural: skeletal muscles. A voluntary, striated (vertebrate) muscle that is associated with the skeleton, and thus move parts of the skeletal system. Supplement. The muscular system of the vertebrates is comprised of various muscles.
Skeletal muscles move the bones of the body. The functional unit of skeletal muscle is a sarcomere, which consists of thick filaments, called myosin, and thin filaments, called actin. The action of the actin and myosin fibers sliding past one another causes the muscle to contract. The neuromuscular junction is where the nerve cell meets the muscle.