ANATOMY

Detailed explanation-1: -M line: M line contains the protein called myomesin and it marks the centre of the sarcomere.

Detailed explanation-2: -Definition: In striated muscle sarcomere, the M line is the attachment site for the thick filaments. The M line is in the center of the A band and, thus, it is in the center of the sarcomere.

Detailed explanation-3: -Within the H-zone is a thin M-line (from the German “mittel” meaning middle), appears in the middle of the sarcomere formed of cross-connecting elements of the cytoskeleton.

Detailed explanation-4: -noun. ˈem-ˌlīn. : a thin dark line across the center of the H zone of a striated muscle fiber. called also M band.

Detailed explanation-5: -The M-line holds together the thick myosin filaments. The Z-line differentiates between each sarcomere. During the contraction of skeletal muscle cells the A-band stays the same length whereas the H-zone and I-band decrease in length. The distance between the Z-lines also decreases.