Musculoskeletal system


Primary Functions of the Musculoskeletal System

  • Support and Protection: Provides a rigid framework for the body and protects delicate internal organs (e.g., the cranium protects the brain; the thoracic cage protects the heart and lungs)

  • Movement and Locomotion: Bones function as levers while skeletal muscles apply force across joints to produce coordinated voluntary movement

  • Mineral Homeostasis and Storage: Acts as a reservoir for critical minerals, predominantly calcium and phosphorus

  • Hematopoiesis: Production of red blood cells, white blood cells, and platelets within the red bone marrow (medulla ossium)

  • Energy Storage: Triglyceride storage within yellow bone marrow adipose tissue

Skeletal System Word Parts and Anatomy

  • Major Combining Forms:

    • Oste/o, Oss/i, Osse/o: Bone

    • Chondr/o: Cartilage

    • Arthr/o, Articul/o: Joint or articulation

    • Myel/o: Bone marrow (or spinal cord)

    • Synovi/o, Synov/o: Synovial membrane, synovial fluid

    • Burs/o: Bursa (fluid-filled sac reducing friction)

    • Ligament/o: Ligament (connects bone to bone)

  • Anatomical Structures of Long Bones:

    • Diaphysis: The main elongated shaft of a long bone

    • Epiphysis: The proximal and distal ends of a long bone, containing spongy (cancellous) bone and red marrow

    • Metaphysis: The narrow growth zone between the diaphysis and epiphysis, containing the epiphyseal plate in growing bone

    • Periosteum: Tough, fibrous vascular membrane covering the outer surface of bone, crucial for bone repair and nourishment

    • Endosteum: Thin vascular membrane lining the inner medullary cavity

    • Compact (Cortical) Bone: Dense, hard outer layer composed of microscopic units called osteons

    • Spongy (Cancellous/Trabecular) Bone: Porous interior lattice composed of trabeculae housing red marrow

  • Cellular Components of Bone:

    • Osteoblasts: Bone-forming cells that secrete collagen and initiate calcification

    • Osteocytes: Mature bone cells that maintain daily bone tissue metabolism

    • Osteoclasts: Multinucleated cells derived from monocytes that break down and resorb bone matrix

  • Divisions of the Skeleton:

    • Axial Skeleton (8080 bones): Skull, hyoid bone, vertebral column, ribs, and sternum

    • Appendicular Skeleton (126126 bones): Upper extremities, pectoral girdle (clavicle, scapula), lower extremities, and pelvic girdle (ilium, ischium, pubis)

Muscular System Word Parts and Anatomy

  • Major Combining Forms:

    • My/o, Myos/o, Muscul/o: Muscle

    • Fasci/o: Fascia (sheet of fibrous connective tissue enclosing muscles)

    • Tend/o, Tendin/o, Ten/o: Tendon (dense cord attaching muscle to bone)

    • Kinesi/o: Movement or motion

    • Leiomy/o: Smooth (visceral) muscle

    • Rhabdomy/o: Striated (skeletal) muscle

  • Muscle Tissue Types:

    • Skeletal Muscle: Striated, multinucleated, under voluntary control

    • Smooth Muscle: Non-striated, single central nucleus, involuntary, found in walls of internal organs and blood vessels

    • Cardiac Muscle: Striated, involuntary, branching fibers with intercalated discs located exclusively in the myocardium

  • Body Movement Terminology:

    • Abduction: Moving a body part away from the median plane

    • Adduction: Moving a body part toward the median plane

    • Flexion: Decreasing the angle between articulating bones

    • Extension: Increasing the angle between articulating bones

    • Dorsiflexion: Bending the foot upward toward the shin

    • Plantar Flexion: Pointing the toes downward toward the ground

    • Supination: Rotating the forearm so the palm faces anteriorly or upward

    • Pronation: Rotating the forearm so the palm faces posteriorly or downward

    • Circumduction: Circular movement of a limb combining flexion, extension, abduction, and adduction

Pathological Conditions and Clinical Terminology

  • Bone Disorders:

    • Osteoporosis: Marked reduction in bone density and mass, leading to bone fragility and fracture susceptibility

    • Osteopenia: Subnormal bone calcification or bone mass less severe than osteoporosis

    • Osteomalacia: Softening of bones due to impaired mineralization, commonly caused by vitamin D deficiency (termed rickets in children)

    • Osteomyelitis: Bacterial or fungal infection and inflammation of bone and bone marrow

    • Ewing Sarcoma & Osteosarcoma: Malignant primary bone tumors

  • Joint Disorders:

    • Osteoarthritis (OA): Progressive non-inflammatory degeneration of articular cartilage and hypertrophic bone formation

    • Rheumatoid Arthritis (RA): Chronic systemic autoimmune disease causing bilateral inflammation of synovial membranes and severe joint deformity

    • Gout (Gouty Arthritis): Metabolic disease characterized by hyperuricemia and intra-articular monosodium urate crystal deposition

    • Ankylosing Spondylitis: Chronic inflammatory disease that causes fusion of the vertebrae

    • Subluxation: Partial or incomplete dislocation of a joint

  • Spinal Curvatures:

    • Kyphosis: Abnormal thoracic curvature forming an exaggerated posterior hump

    • Lordosis: Exaggerated anterior lumbar curvature (swayback)

    • Scoliosis: Abnormal lateral curvature of the spine

  • Muscular and Soft Tissue Disorders:

    • Myasthenia Gravis (MG): Autoimmune disorder characterized by weakness and rapid fatigue of voluntary skeletal muscles due to acetylcholine receptor antibody destruction

    • Fibromyalgia: Chronic musculoskeletal syndrome featuring widespread pain, fatigue, and distinct tender trigger points

    • Polymyositis: Chronic inflammatory myopathy causing progressive muscle weakness

    • Carpal Tunnel Syndrome (CTS): Compression neuropathy of the median nerve within the carpal canal of the wrist

Diagnostic Procedures, Surgical Interventions, and Suffixes

  • Diagnostic Procedures:

    • Arthrocentesis: Percutaneous puncture of a joint space to aspirate synovial fluid for diagnostic analysis or pain relief

    • Arthroscopy: Endoscopic visualization and minimal access examination of internal joint structures

    • Dual-Energy X-Ray Absorptiometry (DEXA): Radiographic density scan quantifying bone mineral density (BMD) at the hip and lumbar spine

    • Electromyography (EMG): Recording and evaluation of the electrical activity generated by skeletal muscle tissue

  • Surgical Terms and Suffixes:

    • -clasia, -clasis: Surgical breaking or fracturing (e.g., osteoclasis)

    • -desis: Surgical fusion, fixation, or binding together (e.g., arthrodesis)

    • -lysis: Separation, destruction, or loosening of adhesions (e.g., tenolysis)

    • -plasty: Surgical repair, restoration, or reconstruction (e.g., arthroplasty)

    • -rrhaphy: Surgical suturing (e.g., myorrhaphy)

    • -tomy: Surgical incision or cutting (e.g., osteotomy, tenotomy)

    • Closed Reduction: Realignment of bone fragments without surgical incision

    • Open Reduction Internal Fixation (ORIF): Surgical realignment of fractured bones accompanied by internal hardware stabilization (plates, screws, pins)