Biology · Locomotion and Movement · NEET
Under a microscope a skeletal muscle fibre shows alternate dark and light bands. This striped look comes from the ordered arrangement of two proteins, actin (thin) and myosin (thick), inside the myofibrils. NCERT states the striated appearance is due to the distribution pattern of actin and myosin. So striated and skeletal go together for NEET.
A muscle fibre is one whole muscle cell, lined by the sarcolemma and filled with sarcoplasm. Inside that single fibre lie many thread-like myofibrils arranged in parallel. So a myofibril is a part inside a fibre, not the fibre itself. Do not swap these two words in the exam.
Many muscle fibres are grouped into a bundle called a fascicle, and these bundles are held together by a common collagenous connective tissue layer. This is exactly why the NEET 2023 statement 'muscle bundles are held together by collagenous connective tissue' was marked correct.
Skeletal muscle is voluntary: you control it with your will through the somatic nervous system. It is attached to skeletal elements (bones) and moves body parts like limbs. Compare this with smooth muscle and cardiac muscle, which are involuntary.
A skeletal muscle fibre is a syncytium, meaning its sarcoplasm contains many nuclei in one cell. These nuclei sit at the edge (peripheral), unlike cardiac muscle where nuclei are central. Peripheral, multiple nuclei is a common NEET identification clue.
The sarcoplasmic reticulum (the muscle's endoplasmic reticulum) is the store house of calcium ions. When a signal arrives, it releases Ca2+ into the sarcoplasm to start contraction. NCERT tests this exact line often.
Which of the following statements are correct regarding skeletal muscle? A. Muscle bundles are held together by collagenous connective tissue layer called fascicle. B. Sarcoplasmic reticulum of muscle fibre is a store house of calcium ions. C. Striated appearance of skeletal muscle fibre is due to distribution pattern of actin and myosin proteins. D. M line is considered as functional unit of contraction called sarcomere.
Three types of muscle tissue are shown as (a), (b) and (c): (a) Long, parallel, cylindrical striated fibres with peripheral nuclei. (b) Spindle-shaped non-striated cells tapering at both ends with a single central nucleus. (c) Striated, branched fibres joined end-to-end with central nuclei. Identify the correct matching pair along with location:
Try the real previous-year questions from this chapter — each with the answer and a full solution.
It is the muscle attached to your bones that you move on purpose, like the biceps or triceps. It looks striped (striated) under a microscope and is voluntary.
That it is striated, voluntary, and attached to skeletal elements. Also remember fibres are bundled into fascicles held by collagen, each fibre has peripheral nuclei, and the sarcoplasmic reticulum stores calcium.
Almost every year NEET asks to identify muscle types or checks facts like the sarcomere definition, calcium store, and striations. Getting skeletal muscle structure clear helps you also answer smooth and cardiac muscle comparison questions.
A fascicle is a bundle of many muscle fibres. Several fascicles are held together by a common collagenous connective tissue layer to build one whole muscle.
Each skeletal muscle fibre is a single cell, but it is a syncytium: one cell holding many nuclei. Many such fibres together, grouped into fascicles, form the whole muscle.
