Both skeletal and cardiac muscle look striated (cross-banded) under a microscope, but skeletal muscle is voluntary, made of long unbranched cylindrical fibres with many nuclei pushed to the side, while cardiac muscle is involuntary, made of branched fibres joined end-to-end by intercalated discs and it never gets tired. Memory hook: "Skeletal = you decide, Cardiac = never tired and branched with discs." NCERT clearly states both are striated, so NEET traps you by testing voluntary vs involuntary and the intercalated disc, not the striations.
Both skeletal and cardiac muscle are striated, so NEET tests the real differences: skeletal is voluntary, unbranched, with peripheral nuclei and can fatigue; cardiac is involuntary, branched, has a central nucleus, is joined by intercalated discs, and never fatigues.
Your doubts, answered
Is cardiac muscle striated or non-striated? I keep mixing it up.
Cardiac muscle IS striated. NCERT (Ch 20, Locomotion and Movement) says clearly that cardiac muscles are striated, just like skeletal muscle. Only smooth (visceral) muscle is non-striated. So striation does NOT separate skeletal from cardiac. The real separators are: skeletal is voluntary and unbranched; cardiac is involuntary, branched, and has intercalated discs.
If cardiac muscle is striated like skeletal, why is one voluntary and the other involuntary?
Striation only tells you how actin and myosin proteins are arranged (the cross-bands). It has nothing to do with control. Skeletal muscle is attached to bones and you move it by will, so it is voluntary. Cardiac muscle is myogenic, meaning it beats on its own from the nodal tissue (SA node), and the nervous system only speeds it up or slows it down, it does not start each beat. That is why cardiac is involuntary even though it looks striated.
What exactly are intercalated discs and which muscle has them?
Intercalated discs are special junctions that join adjacent cardiac muscle cells end-to-end. They allow the signal to pass quickly from cell to cell so the whole heart contracts together as one unit. Only cardiac muscle has intercalated discs. Skeletal and smooth muscle do NOT have them. NEET has directly asked this: a 2021 question marked 'communication by intercalated discs' as WRONG for smooth muscle because discs belong to cardiac muscle only.
How are the nuclei arranged differently in skeletal vs cardiac muscle?
A skeletal muscle fibre is a syncytium, meaning many nuclei sit in one long fibre, and these nuclei are pushed to the edge (peripheral). Cardiac muscle fibres are branched and usually have one central nucleus per cell. So 'many peripheral nuclei + unbranched cylinder' = skeletal, and 'central nucleus + branched fibres joined by discs' = cardiac.
Why does cardiac muscle never get tired but skeletal muscle does?
Skeletal muscle can be worked so hard that lactic acid builds up and it goes into fatigue (this is why you cannot sprint forever). Cardiac muscle is built to work continuously your whole life without fatigue, helped by a rich blood supply (the coronary system) that keeps giving it oxygen. So 'fatigue = skeletal', 'no fatigue = cardiac' is a safe NEET rule.
⚠️ The NEET trap ✗ Picking cardiac muscle as the 'non-striated' one, or thinking striation is what makes skeletal voluntary and cardiac involuntary. ✓ Both skeletal AND cardiac muscle are striated. The differences that matter are: voluntary (skeletal) vs involuntary (cardiac), unbranched cylindrical vs branched fibres, peripheral many nuclei vs central nucleus, and intercalated discs present only in cardiac. 🧠 NTA loves the word 'striated' here.
Real NEET questions
2024
Three types of muscle tissue are shown as (a), (b) and (c): (a) Long, parallel, cylindrical striated (cross-banded) fibres with peripheral nuclei. (b) Spindle-shaped (fusiform) non-striated cells tapering at both ends, each with a single central nucleus. (c) Striated, branched fibres joined end-to-end with central nuclei. Identify the correct matching pair along with their location in the human body (Name of muscle / location):
Solution: Figure (a) with long, parallel, cylindrical striated fibres and peripheral nuclei is SKELETAL muscle (e.g. triceps). Figure (c) with striated but BRANCHED fibres joined end-to-end is CARDIAC muscle (heart). Note both (a) and (c) are striated, the difference is unbranched cylinder + peripheral nuclei (skeletal) vs branched fibres + central nuclei (cardiac). Figure (b), non-striated and spindle-shaped, is smooth muscle (stomach). Only option A matches all three correctly.
2021
Which of the following statements wrongly represents the nature of smooth muscle?
A · Communication among the cells is performed by intercalated discs ✓
B · These muscles are present in the wall of blood vessels
C · These muscles have no striations
D · They are involuntary muscles
Solution: Smooth muscle is non-striated, involuntary, and found in walls of hollow organs including blood vessels (so B, C, D are correct for smooth muscle). Intercalated discs are junctions found ONLY between cardiac muscle cells, not in smooth (or skeletal) muscle. So statement A wrongly describes smooth muscle. This confirms the key skeletal-vs-cardiac point: intercalated discs are unique to cardiac muscle.
Solved Locomotion and Movement NEET PYQs
Try the real previous-year questions from this chapter — each with the answer and a full solution.
Yes. NCERT states both skeletal and cardiac muscles are striated (cross-banded). Only smooth/visceral muscle is non-striated. So striation cannot be used to tell skeletal and cardiac apart.
What is the single most important difference for NEET?
Skeletal muscle is voluntary and unbranched; cardiac muscle is involuntary, branched, and has intercalated discs. The intercalated disc is the most frequently tested unique feature of cardiac muscle.
Which muscle has intercalated discs?
Only cardiac muscle. These discs connect cardiac cells end-to-end so the heart contracts as one unit. Skeletal and smooth muscle do not have them.
Why is cardiac muscle called involuntary if it is striated?
Because it is myogenic, it generates its own beat from nodal tissue (SA node), and you cannot control each heartbeat by will. Striation only reflects the actin-myosin arrangement, not nervous control.
Does cardiac muscle get fatigued like skeletal muscle?
No. Cardiac muscle is fatigue-resistant and works continuously for life, supported by a rich coronary blood supply. Skeletal muscle can fatigue when lactic acid accumulates.
