Musculoskeletal system for beginners | MPO training 8

The Musculoskeletal system for beginners explains bones, muscles, and joints in an easy way. This article helps you understand how your body moves and stays strong. If you're a Medical Promotion Officer (MPO), you must know these basics to talk with doctors confidently.

This article uses simple English and helpful images to make learning easy. This makes your learning faster and more effective.

Musculoskeletal System: A system of bones, joints, their related structures and muscles.

The musculoskeletal system provides form, support, stability, and movement to the body. It is made up of the bones of the skeleton, muscles, cartilage, tendons, ligaments, joints, and other connective tissue that supports and binds tissues and organs together.

Adult skeleton consists of 206 bones.

Diagram: musculoskeletal system

Functions of Musculoskeletal System

Hard framework of bones of human body.

Diagram: Skeleton Structure

• Axial Skeleton
• Appendicular Skeleton
• Sternum and Ribs

Junction of two bones is referred to as a joint.

• a. Fibrous or Fixed joint
• b. Cartilaginous or slightly movable joint
• c. Synovial or freely movable joints

Diagram: Synovial Joint part

What is Synovial Joint?

• (i) Articular Capsule
• (ii) Articular Cartilage
• (iii) Synovial Fluid

(i) Articular Capsule: The articular capsule surrounds the joint and is continuous with the periosteum of articulating bones.

• Fibrous layer (outer): consists of white fibrous tissue, known as the capsular ligament. It holds together the articulating bones and supports the underlying synovium.
• Synovial layer (inner): a highly vascularized layer of serous connective tissue. It absorbs and secretes synovial fluid, and is responsible for the mediation of nutrient exchange between blood and joint. Also known as the synovium.

(ii) Articular Cartilage: The articulating surfaces of a synovial joint (i.e. the surfaces that directly contact each other as the bones move) are covered by a thin layer of hyaline cartilage.

The articular cartilage has two main roles: 

• Minimizing friction upon joint movement.
• Absorbing shock.

(iii) Synovial Fluid: The synovial fluid is located within the joint cavity of a synovial joint.

• Lubrication 
• Nutrient distribution 
• Shock absorption 

Articular cartilage is relatively avascular, and is reliant upon the passive diffusion of nutrients from the synovial fluid.

Accessory Ligaments: The accessory ligaments are separate ligaments or parts of the joint capsule. They consist of bundles of dense regular connective tissue, which is highly adapted for resisting strain. This resists any extreme movements that may damage the joint.

Diagram: Accessory Structures of a Synovial Join

Innervation: Synovial joints have a rich supply from articular nerves.

The innervation of a joint can be determined using Hilton's Law - 'the nerves supplying a joint also supply the muscles moving the joint and the skin covering their distal attachments.

Articular nerves transmit afferent impulses, including proprioceptive (joint position) and nociceptive (pain) sensation.

Vasculature: Arterial supply to synovial joints is via articular arteries, which arise from the vessels around the joint. The articular arteries are located within the joint capsule, mostly in the synovial membrane. 

A common feature of the articular arterial supply is frequent anastomoses (communications) in order to ensure a blood supply to and across the joint regardless of its position. In practice this usually means arteries are above and below a joint, curving round each side of it and joining via small connecting vessels.

The articular veins accompany the articular arteries and are also found in the synovial membrane.

Osteoarthritis is the most common form of joint inflammation (arthritis). It stems from heavy use of articular joints over the course of many years, which can result in the wearing away of articular cartilage, and often the erosion of the underlying articulating surfaces of bones as well.

The changes which occur are irreversible and degenerative. This results in the decreased effectiveness of articular cartilage as a shock absorber and lubricated surface, as well as the roughened edges causing further damage.

As a result of this degeneration, repeated friction can cause symptoms of joint pain, stiffness and discomfort. This condition usually affects joints that support full body weight, such as the hips and the knees.

Arthritis can also come about through other causes, including;

• As a result of infection, due to the ease with which blood (and any associated bacteria) can enter the joint cavity via the synovial membrane;
• Due to auto-inflammatory causes, as in rheumatoid arthritis, or;
• As a result of infection but not involving infection of the joint itself, as in reactive arthritis.

• Articular Capsule.
• Synovial Layer (Inner & Outer).
• Articular Cartilage.
• Synovial Fluid.
• Ligament: It is a band of strong muscular tissue.
• Tendon: A cover of strong fibrous connective tissue.
• Capsule: A two layered membrane that covers the synovial joint.
• Bursae: A pad like sac or cavity close to the joints.

1. Gliding joint or Plain joint
2. Ball and Socket joint
3. Condylar joint
4. Pivot joint
5. Saddle joint

1. Synovial joints are the most common type of joint in the body.
2. A key structural characteristic for a synovial joint is the presence of a joint cavity.
3. This synovial fluid filled space is the site at which the articulating surfaces of the bones contact each other.
4. The articulating bone surfaces at a synovial joint are covered with fibrous connective tissue or cartilage.
5. This gives the bones of a synovial joint the ability to move smoothly against each other, allowing for increased joint mobility.
6. Synovial joints are characterized by the presence of a joint cavity. 
7. The walls of this space are formed by the articular capsule, a fibrous connective tissue structure that is attached to each bone just outside the area of the bone's articulating surface. 
8. The bones of the joint articulate with each other within the joint cavity. 
9. Ligaments are required to bind the bones together 
10. At many synovial joints, additional support is provided by the muscles and their tendons that act across the joint. A tendon is the dense connective tissue structure that attaches a muscle to bone.

Structure of the body that converts the chemical energy of ATP into mechanical work.

• Striated or Voluntary Muscle : It can move at our will.
• Visceral or Involuntary muscles : Do not move under our will.
• Cardiac Muscle : It is also a muscle of involuntary nature.

Pain is an unpleasant sensory and emotional experience associated with acute or potential tissue damage. It is a protective mechanism for the body.

• Acute pain
• Chronic pain
• Spasmodic pain

Inflammation is the active defensive response / reaction process of tissues against injury, infection etc.

• Pain
• Redness
• Heat and
• Swelling

Diagram: Mechanism of Action of Inflammation and NSAIDs

Pain and Inflammation: Synthesis

Rheumatism: Classification

Osteoarthritis: It is a non-inflammatory joint disease characterized by the degeneration of articular cartilage.

Rheumatoid Arthritis: It is a most common and chronic form of arthritis. It involves more than one joint.

Articular Rheumatism : Sign and Symptoms: 

• Starts gradually.
• Pain and stiffness is common.
• Patients complain of early morning stiffness.
• Progression of the disease with marked inflammation is observed.
• Tests of rheumatoid factors are positive in 70-80% of patients.

The word juvenile means childhood. Usually it occurs in children under 16 years of age. It is characterized by joint inflammation along with high-grade fever.

Articular Rheumatism: Ankylosing Spondylitis 

Ankylosing Spondylitis is a progressive chronic arthritis. The word Ankylosis means stiff joint condition and Spondylitis means inflammation of vertebrae.

• Pain is worse after exercise.
• Low back pain and morning stiffness.
• Pain around the ribs may.
• Marked rigidity of spine may occur.

Sprain: Injury to ligaments that causes pain and loss of movement.

Strain: Trauma to the muscle that results from excessive physical effort.

Myalgia: Pain in the muscle.

Arthralgia: Pain within a joint without any definite cause of joint disease.

Dysmenorrhoea: Painful or difficulty in menstruation.

Sciatica: Severe pain felt at the back of the thigh.

Lumbago: Slow but continuous pain in the lumbar part of the back.

Dislocation: Displacement of bone from its normal location.

Renal colic: Colic means pain, resulting from periodic spasm in an abdominal organ. Renal colic means spasm of ureter due to a stone.

Gout: Painful condition due to deposition of uric acid crystal in the small peripheral joints and the tissues around.

• Sudden onset of severe pain with marked inflammation and tenderness.
• Fever, sweating, Loss of appetite.
• Raised serum uric acid level.

• Paracetamol

• Ibuprofen
• Ketoprofen

• Diclofenac
• Naproxen
• Salicylic Acid
• Aspirin

Answer: The musculoskeletal system is the part of your body that includes bones, muscles, and joints. It helps you move, stand, walk, and do daily activities. It also gives your body shape and support.

4. Why is the musculoskeletal system important for MPOs to understand?

Answer: As a Medical Promotion Officer (MPO), understanding this system helps you explain how certain medicines work, especially those used for bone or muscle pain. It builds your confidence when speaking with doctors.

Answer: Bones give structure, muscles create movement, and joints connect the parts. These work together like a team so your body can move smoothly and stay strong.

Answer: Common issues include arthritis, muscle strain, back pain, and bone fractures. Knowing these helps an MPO explain treatments better to healthcare professionals.

Understanding the Musculoskeletal system for beginners is very important if you want to work as a Medical Promotion Officer (MPO). This article gives you simple and useful knowledge about the human body's movement system. You can use this information to talk clearly with healthcare professionals. It helps you grow your confidence as an MPO. Remember, learning the basics is the first step to success. So, keep practicing and stay curious!