The region at the ends of the $A$-band of two adjoining sarcomeres is called

The biceps and triceps muscles are found in

In the given diagram,which label represents the $I$-band?

Which of the following statements is correct regarding skeletal muscles?

Which of the following statements are false regarding the muscle structure?
$I.$ In the centre of each $I$-band is an elastic fibre ($Z$-line) which bisects it.
$II.$ Thin filaments are firmly attached to the $Z$-line.
$III.$ $M$-line is a fibrous membrane in the middle of $A$-band.
$IV.$ $A$ sarcomere comprises one full $A$-band and two half $I$-bands.

Where are calcium ions stored in muscle cells?