(i) Myofibril are arranged in sacromeres. The sarcomere is the zone between two Z lines. A-band is present in centre of sarcomere, near to it is I-band.
(ii) The skeletal muscle has alternate A and I bands.
(iii) These are called anisotropic (dark) and isotropic (light) bands. Z-line lies in centre of Iband but middle of A band is H-zone.
(iv) Sarcoplasm has many thick and thin filaments. H-zone has only thick filaments but I band contains thin filaments.
(v) The remaining part of A band has both thin (actin) and thick (myosin) filaments.
(vi) The thin filaments have actin protein but thick are made of myosin.