The Musculoskeletal System

Arnie Shapiro, M.D.
January – February 2026 • Vol 4, No 20

We move. We don’t have to think about it, usually. We might mentally plan a move, and our body proceeds with the motions. The Nervous System is the director, choreographer, and conductor, and the Musculoskeletal System is actor, dancer, and doer.

The Musculoskeletal System is a marvel of mechanics. Comprised of bones, joints, muscles, ligaments, and tendons, it allows us to move in myriad ways. Our movements are accomplished by bones being pulled on by muscles. The degree of coordination is extraordinary. If we take a walk, tens of millions of nerve fibers are activated and, in turn, tens of millions of muscle fibers are doing concerted contractions and relaxations.

Two necessary biologic functions occur in all muscle contraction:

• There is a Neuromuscular Junction, where nerve branches communicate to muscle fibers. (This is a nerve-muscle synapse, as compared with a nerve-nerve synapse). The Neurotransmitter, Acetylcholine is released at the nerve ending and “fires” the muscle contraction mechanism.
• The muscle fibers are loaded with millions of contractile units called “sarcomeres.” Sarcomeres are microscopic columns made of the specialized proteins, Actin and Myosin, that, when stimulated, can slide past each other, shortening the muscle fibers.

Muscles are attached to bones by tendons. Tendons are strong bundles of connective tissue, with powerful attachments to muscle origins and insertions. The near part of a muscle is the “origin”, and the far part is the “insertion.” Our bodies have just over 600 muscles. They all attach to bones (with the exception of some facial expression muscles which move skin or cartilage). Most muscles occur

in symmetrical pairs. Central muscle groups are attached to skull, spine, or ribs. Peripheral muscles have attachments in arms and legs. The near part of a muscle is the “origin”, and the far part of the muscle is the “insertion.”

The Diaphragm is a special dome-shaped muscle that paces basal breathing (breathing at rest). If enhanced breathing is needed, intercostal muscles can expand and contract the rib cage. The heart is a miracle muscle that contracts rhythmically, virtually every second of our lives!

The number of muscle and bones in the human body is surprisingly high. We have 650 muscles and 206 bones! Muscles comprise 30–40% of our total body weight. Bones comprise approximately 15% of our body weight.

The functions of the musculoskeletal system include: flexion and extension of joints, posture maintenance, stabilization of joints, instantaneous and reflexive balance controls, chewing and swallowing.  In addition, muscles accomplish breathing, and the intercostal muscles and bones protect our chest contents.

Another function muscles perform is heat production. When body temperature falls, as in a cold environment, the nervous system signals muscles to vibrate to generate heat. This vibration is unnoticed by us, to generate heat. A magnified form of it, shivering, is very noticeable.

In addition to complex innervation, there is complex blood circulation involved in every muscle. As soon as a muscle starts to work, the Autonomic Nervous System sends signals to allow widening of muscular arteries for increased blood flow. The blood brings extra oxygen and glucose, crucial for the muscle work. Conditioning (repeated exercise), optimizes the blood circulation, including to the heart itself.

Bones are formed in fetal development. They are made of a mesh of collagen (protein) fibers, along which are deposits of the minerals Calcium and Phosphorous. This forms a cement that is both light and strong. Bones are hollow. The spongy inner compartment is called the marrow. In the largest bones, the marrow is amazingly productive of Red Blood Cells and White Blood Cells.

In youth, bone size increases in length and thickness and becomes denser. There is maximal density in young adulthood. Bone density is best maintained by a diet sufficient in Calcium and Vitamin D and by regular exercise, especially weight-bearing and balance. Muscles and bones thrive on activity. Inactivity, if prolonged, causes muscle atrophy (loss of size and strength), and osteoporosis (loss of bone density). Prolonged poor diet and inactivity also result in both bone and muscle losses.

Activity should be consistent and varied. Most authorities recommend a combination of moderate aerobic activities (walking, running, Nordic skiing, swimming, cycling), and strength and balance activities, like push-ups, squats, lunges, dumbbells, barbells, Yoga, and Tai Chi.

Warm-ups are recommended, using lighter movements (limberings) of the muscles. Stretching is beneficial, during and/or after the exercise session. Hold stretches 20–30 seconds, with moderation and no pain.

How can we best take care of our amazing Musculoskeletal System?

• Stay physically active. 20–30 minutes per day, 4–7 days per week, of moderate aerobic activity.
• Include strength training and exercise that requires balance. Do weight-bearing exercises.
• Practice good posture and ergonomics. Avoid prolonged sitting. Move every 30–45 minutes.
• Maintain joint mobility and flexibility.
• Protect your bones: use Calcium and Vitamin D supplements.
• Maintain a healthy body weight.
• Prioritize recovery. Sleep 7–9 hours nightly. Take rest days between intense workouts.
• Avoid overuse injuries. Be gradual in exercise increases. Cut back if pain occurs.
• Stay hydrated. Drink water at all parts of the day.
• No smoking. Avoid excessive alcohol.
• Get regular check-ups:
  • Bone density after age 50.
  • Sports medicine or orthopedic check-ups if pain.
  • Physical Therapy if persistent pain.

In summary, the Musculoskeletal System is our gift of movement from the Tree of Life, perfected over 500 million years! It is very observable, and subject to our volition, more than our other systems. It’s worth being grateful for, taking care of, and admiring.

—Namaste!

Dr. Shapiro is a career clinic physician who has utilized relaxation techniques with many of his patients. Prior articles by Dr. Shapiro can be found on his Columnist page at NaturalLifeNews.com. His YouTube channel is: “Arnie Shapiro, MD • Breathing Easy.” Email Dr. Shapiro at: alloydshapiro@gmail.com.