Animal Tissues - Muscular Tissue

Muscular tissue is classified by NCERT into skeletal, smooth and cardiac types based on location, structure and control. Cardiac muscle is found only in the heart wall and its fibres are striated like skeletal muscle, but they are uniquely branched and connected end to end by intercalated discs, which are specialised junctions that allow rapid, synchronised conduction of contraction signals. This branching plus the discs is the defining microscopic feature separating it from skeletal muscle. Striations are present in both cardiac and skeletal muscle, so that property cannot distinguish them. Voluntary nervous control is a feature of skeletal muscle attached to bones, whereas cardiac muscle is involuntary and myogenic, making this option incorrect for distinguishing in favour of cardiac uniqueness. Spindle-shaped uninucleate cells describe smooth muscle of visceral organs, not cardiac fibres which are typically uninucleate but cylindrical and branched. As stated in NCERT Class 11, Chapter 7, intercalated discs are characteristic junctions of cardiac muscle. A structural sanity check confirms that only the branched, disc-linked architecture is exclusive to heart muscle among the listed options.