Human Locomotor System: Bones, Joints, Muscles, and First Aid

Locomotor System

Bones

The skeletal system consists of 200 bones.

• Long Bones: Femur, ulna, radius
• Short Bones: Vertebrae, phalanges
• Flat Bones: Shoulder blade, skull bones, pelvis
• Irregular Bones: Facial bones

Composition of Bones

Mineralized connective tissue

• Cells (2%):
  • Osteocytes: Mature cells
  • Osteoclasts: Destroy tissue
  • Osteoblasts: Create tissue
• Fibers (95%): Tropocollagen
• Fundamental Substance (3%): H₂O

Structure of Bones

• Compact Bone Tissue: In diaphysis (long bones) and flat outer layers
  • Osteons: Small vessels that make up the bone
  • Yellow Marrow: Consisting of fat, feeds the cells

Functions of Bones

• Support the body
• Protect vital organs
• Facilitate movement with joints and muscles
• Store minerals
• Manufacture red blood cells

Joints

• Synarthrosis: Fixed, no movement, composed of cartilage tissue (e.g., skull bones)
• Amphiarthrosis: Semi-mobile with small movements (e.g., tibiofibular syndesmosis, pubic symphysis)
• Synovial: Mobile (e.g., knee), allowing rotation, flexion, extension, separation, adduction, circumduction, supination, pronation
  • Ligaments: Fibrous, thick, and inelastic (internal and external)
  • Joint Capsule: Composed of elastic and reticular fibers
  • Synovial Membrane (inner layer): Generates synovial fluid that facilitates movement
  • Meniscus: Helps with joint alignment
  • Cartilage: Covers the bone and counterbalances weight

Skeletal Joints (Primarily Diarthrosis)

• Shoulder Girdle: Sternum-clavicle and scapula (frozen joints), humerus and scapula (mobile joints)
• Elbow: Humerus with ulna and radius (trochlear), ulna and radius (condylar)
• Wrist: Condylar
• Metacarpophalangeal joints
• Phalangeal joints
• Hip: Femur and hip bone
• Knee: Femur, patella, tibia (trochlear, flexion, and extension)
• Ankle: Tarsal bones
  • Tibia, fibula, calcaneus: Pulley (flexion and extension)
  • Calcaneus and other bones: Condyle (lateral movement)

Muscles

• Smooth Muscle: Uninuclear fibers (lungs, stomach, arteries, internal organs capable of movement)
• Striated Muscle Tissue: Grooved, multinuclear
  • Cardiac Muscle Tissue: Only in the heart, self-contracting
  • Skeletal Muscle Tissue: Allows voluntary movement controlled by the central nervous system
    • Muscle Fibers:
      • Red (slow-twitch)
      • White (fast-twitch)

Muscle fibers coalesce into bundles, surrounded by epimysium.

Muscle Contractions

• Static Contraction: No movement
• Dynamic Contraction:
  • Concentric: Muscle shortening
  • Eccentric: Muscle lengthening

Classification of Skeletal Muscles

• By Action: Flexors, extensors, abductors, rotators
• By Function: Agonist (main function)

First Aid

PAS: Protect, Alert, Assist

• Protect the casualty
• Alert people around
• Assist the victims

Primary Assessment

• CPR (Cardiopulmonary Resuscitation) protocol

Secondary Assessment

Bleeding

• External or Open: Apply pressure to the area
• Internal with External Exit

Disorders of Consciousness

• Fainting: Nausea, cold sweat, dizziness. Lay the person on their back and elevate their legs.
• Syncope: Momentary loss of consciousness. Prevent tongue swallowing, place the head to the side, and elevate the legs once conscious.

Burns

• Grade 1: Redness
• Grade 2: Blisters. Apply cold water and ointment.
• Grade 3: Gray skin. Assess the extent using the rule of nines.

Asphyxia

If the person can cough, encourage it. If not, give five blows to the back between the shoulder blades. If the obstruction persists, perform the Heimlich maneuver (stand behind the person, make a fist, and give a sharp upward thrust below the chest).

Cardiac Arrest

CPR: If the person loses respiration and pulse, perform 2 breaths followed by 30 compressions (two fingers on the sternum).