Musculoskeletal System – Important Questions and Answers (LAQs)

- Skeletal muscles: Striated, voluntary, attached to bones, e.g., biceps and quadriceps.
- Smooth muscles: Unstriated, involuntary, found in internal organs, e.g., stomach wall, intestines.
- Cardiac muscles: Striated, involuntary, branched, found only in the heart.
They differ in structure, control, and function, but all are essential for body movement and survival.

The sliding filament theory explains how muscles contract:
- Nerve impulse releases acetylcholine at neuromuscular junction.
- Calcium ions released from sarcoplasmic reticulum bind troponin.
- Actin sites exposed, myosin heads attach forming cross-bridges.
- ATP hydrolysis provides energy, pulling actin filaments inward.
- Sarcomere shortens, causing contraction.
- When impulse ends, calcium reabsorbed, muscles relax.

Aging reduces bone density (osteoporosis), makes cartilage brittle (osteoarthritis), and causes muscle mass loss (sarcopenia).
Prevention methods include regular exercise, strength training, balanced diet with calcium and vitamin D, and avoiding sedentary lifestyle.

1. Muscle strain: Overstretching → pain, swelling.
2. Shin splints: Stress on tibia → shin pain.
3. Shoulder injury: Overuse → rotator cuff pain.
4. Lower back pain: Poor posture/exercise form.
5. Tennis elbow: Repeated forearm use → tendon pain.
6. Ankle sprain: Twisting → ligament tear.
7. Groin strain: Excess running/jumping → inner thigh pain.
Treatment: RICE (Rest, Ice, Compression, Elevation), physiotherapy, proper warm-up, correct footwear.

A balanced diet with lean protein, complex carbs, vitamins and minerals supports muscle growth, repair and endurance.
Processed foods with high sugar, fat and sodium reduce recovery, increase inflammation, and weaken muscle performance. Long-term, they contribute to obesity, insulin resistance and poor musculoskeletal health.