What is the full form of the following terms used in muscle structure?
$(1)$ $A$-disc
$(2)$ $I$-disc

Select the correct statements regarding the mechanism of muscle contraction.
$A.$ It is initiated by a signal sent by $\text{CNS}$ via a motor neuron,not a sensory neuron.
$B.$ Neurotransmitter generates an action potential in the sarcolemma.
$C.$ Increased $Ca^{++}$ level leads to the binding of calcium with troponin on actin filaments.
$D.$ Masking of the active site of actin prevents contraction; unmasking leads to contraction.
$E.$ Utilising the energy from $\text{ATP}$ hydrolysis to form a cross-bridge.

The muscular contraction in which the tension remains the same and the mechanical work is also done is called

The major protein in the thick filament of skeletal muscle fibre is

The Achilles tendon is associated with which of the following muscles?

The largest muscle in the human body is: