Musculoskeletal systems

CHAPTER 66: Assessment of the Musculoskeletal System

STRUCTURES AND FUNCTIONS OF THE MUSCULOSKELETAL SYSTEM

  • Composition:

    • Voluntary muscle

    • Connective tissue

    • Bone

    • Cartilage

    • Ligaments

    • Tendons

    • Fascia

    • Bursae

  • Purposes:

    • Protect body organs

    • Provide support and stability

    • Store minerals

    • Allow coordinated movement

BONE FUNCTIONS

  • Support

  • Protect internal organs

  • Enable voluntary movement

  • Blood cell production

  • Mineral storage

MICROSCOPIC STRUCTURE (1 OF 2)

  • Cortical Bone:

    • Compact and dense structure

    • Composed of Osteons, also known as Haversian systems

    • Includes Lamellae and Canaliculi

  • Cancellous Bone:

    • Spongy in nature

    • Contains red or yellow marrow

BONE STRUCTURE

  • Key Components:

    • Periosteum: A dense layer of vascular connective tissue enveloping the bones except at the surfaces of the joints.

    • Osteon (Haversian system): The fundamental functional unit of compact bone, consisting of lamellar bone surrounding a central canal (Haversian canal) that contains blood vessels and nerves.

    • Canaliculi: Microscopic canals between the lacunae of ossified bone.

    • Blood Vessels: Provide necessary nutrients to bone tissues.

MICROSCOPIC STRUCTURE (2 OF 2)

  • Three Types of Bone Cells:

    • Osteoblasts:

    • Bone-forming cells that synthesize and secrete the bone matrix.

    • Osteocytes:

    • Mature bone cells that maintain the bone matrix.

    • Osteoclasts:

    • Cells that break down bone tissue, facilitating bone remodeling.

  • Bone Remodeling Process:

    • Removal of old bone by osteoclasts

    • Deposit of new bone by osteoblasts

GROSS STRUCTURE

  • Anatomy of a Long Bone:

    • Epiphysis: End part of a long bone, initially growing separately from the shaft.

    • Diaphysis: The central shaft of a long bone.

    • Metaphysis: The region between epiphysis and diaphysis.

    • Epiphyseal Plate: Growth plate where bone elongation occurs.

    • Periosteum: Connective tissue layer surrounding the bone.

    • Articular Cartilage: Covers the bone ends at joints to reduce friction and absorb shock.

    • Medullary Cavity: Cavity within the diaphysis containing bone marrow.

    • Compact and Spongy Bone: Types of bone tissue found in long bones.

BONE TYPES

  • Total Skeleton Composition:

    • 206 bones in the adult human body.

  • Types of Bones:

    • Long

    • Short

    • Flat

    • Irregular

    • Sesamoid

JOINTS

  • Joint Definition:

    • An articulation where the ends of two bones are closely positioned and move in relation to one another.

  • Capsule:

    • Encloses the joint in fibrous connective tissue, which includes a Synovial membrane and synovial fluid.

  • Diarthrodial (synovial) Joints:

    • The most common type of joints characterized by a wide range of movement.

CLASSIFICATION OF JOINTS

  • Types of Joints:

    • Fibrous:

    • Joints held together by dense connective tissue, allowing little to no movement.

    • Cartilaginous:

    • Joints connected entirely by cartilage, allowing for limited movement.

    • Synovial Joints:

    • Freely movable joints found in many parts of the body, characterized by the presence of synovial fluid.

STRUCTURE OF DIARTHRODIAL JOINT

  • Key components include:

    • Tendon Sheath: A layer of synovial fluid that surrounds a tendon.

    • Bursa: A small sac of connective tissue that alleviates friction in joint movement.

    • Articular Cartilage: Smooth tissue that covers the ends of bones in synovial joints, reducing friction.

    • Joint Cavity: Space within the joint that allows for free movement.

    • Bone: Main structural units making up the joint.

    • Synovial Membrane: Lines the joint capsule and secretes synovial fluid.

    • Blood Vessel: Supplies nutrients to the joint.

    • Nerve: Provides sensory input to the brain about joint position.

    • Joint Capsule: Surrounds the joint and provides structural integrity.

TYPES OF DIARTHRODIAL JOINTS

  • Joint Movement and Examples:

    1. Hinge Joint

    • Movement: Flexion and extension.

    • Examples: Elbow joint, interphalangeal joints, knee joint.

    1. Ball and Socket Joint (spheroidal)

    • Movement: Flexion, extension, adduction, abduction, circumduction.

    • Examples: Shoulder joint, hip.

    1. Pivot Joint (rotary)

    • Movement: Rotation.

    • Examples: Atlas-axis, proximal radioulnar joint.

    1. Condyloid Joint

    • Movement: Flexion, extension, abduction, adduction, circumduction.

    • Examples: Wrist joint between radial and carpals.

    1. Saddle Joint

    • Movement: Flexion, extension, abduction, adduction, circumduction, opposition.

    • Examples: Carpometacarpal joint of thumb.

    1. Gliding Joint

    • Movement: One surface glides over another surface.

    • Examples: Joints between tarsals, sacroiliac joint, vertebrae articular processes.

CARTILAGE

  • Types of Cartilage:

    • Hyaline Cartilage: Provides support and flexibility.

    • Elastic Cartilage: Offers strength and elasticity.

    • Fibrous Cartilage: Provides tensile strength and absorbs compressive shock.

  • Functions of Cartilage:

    • Support

    • Articulation

    • Protection

    • Growth

MUSCLE: TYPES

  • 1. Cardiac Muscle:

    • Characteristics: Striated and involuntary.

    • Location: Found only in the heart.

    • Function: Demonstrates spontaneous contractions.

  • 2. Smooth Muscle:

    • Characteristics: Nonstriated and involuntary.

    • Location: Found in the walls of hollow structures.

    • Function: Contraction controlled by neuronal and hormonal influences.

  • 3. Skeletal Muscle:

    • Characteristics: Striated and voluntary, accounting for about half of the body’s weight.

    • Function: Requires neuronal stimulation for contraction.

MUSCLE: STRUCTURE

  • Muscle Fiber: Fundamental unit of skeletal muscle responsible for contraction.

  • Myofibrils: Long strands of proteins (actin and myosin) in muscle fibers responsible for contraction.

  • Sarcomere: The basic contractile unit of striated muscle tissue.

  • Myosin: Thick filament involved in muscle contraction.

  • Actin: Thin filament that interacts with myosin for contraction.

  • Contractions: Serve various purposes, including posture, movement, and expression.

  • Types of Contractions:

    • Isometric: Muscle length remains unchanged while tension increases.

    • Isotonic: Muscle length changes while tension remains constant.

  • Muscle Adaptation:

    • Atrophy: Decrease in muscle mass and strength due to disuse.

    • Hypertrophy: Increase in muscle mass and strength due to increased workload.

  • Types of Muscle Fibers:

    • Slow-Twitch Fibers: Specialized for endurance and prolonged activity.

    • Fast-Twitch Fibers: Specialized for quick bursts of activity.

NEUROMUSCULAR JUNCTION (1 OF 2)

  • Skeletal Muscle Function: Requires a nerve impulse to contract.

  • Motor Endplate: Specialized area on a muscle cell where the motor neuron communicates with the muscle fiber.

  • Neuromuscular Junction: The synapse or junction between a motor neuron and a skeletal muscle fiber.

  • Acetylcholine Release: Presynaptic neurons release acetylcholine which binds to receptors on the muscle fiber's sarcolemma.

  • Calcium Release: Sarcoplasmic reticulum releases calcium ions, triggering the contraction of myofibrils.

  • Tetany: Condition that may occur due to low calcium levels, characterized by sustained muscle contraction.

NEUROMUSCULAR JUNCTION (2 OF 2)

  • Components of Neuromuscular Junction:

    • Motor neuron fiber

    • Schwann cell: A type of glial cell that insulates axons.

    • Myelin Sheath: Insulating layer formed around the nerves.

    • Synaptic Vesicles: Containing acetylcholine for neurotransmission.

    • Sarcolemma: The membrane surrounding a muscle fiber.

    • Acetylcholine Receptor Sites: Points of binding for acetylcholine.

    • Synaptic Cleft: Space between the motor neuron and the muscle fiber's sarcolemma.

    • Motor Endplate: The part of the muscle fiber membrane that contains receptors for acetylcholine.

ENERGY SOURCE

  • Adenosine Triphosphate (ATP):

    • The direct energy source for muscle contractions.

  • **ATP *Synthesis:*

    • Synthesized through cellular oxidative metabolism.

    • Conversion of ATP to Adenosine Diphosphate (ADP) releases energy for muscle contractions.

  • Phosphocreatine:

    • Can be converted to creatine to help replenish ATP levels.

  • Glycolysis:

    • A metabolic pathway that generates ATP, especially when oxygen (O2) supply is inadequate.

LIGAMENTS AND TENDONS

  • Tendons:

    • Attach muscles to bones, transferring forces that allow movement.

  • Ligaments:

    • Attach bones to bones, providing stability to joints.

  • Characteristics:

    • Composed of fibrous connective tissue with poor blood supply, resulting in a slow repair process after injury.

FASCIA AND BURSAE

  • Fascia:

    • Layers of connective tissue that provide strength to muscles; includes:Superficial and Deep Fascia.

  • Bursae:

    • Small sacs of connective tissue located at bony prominences or joints, which relieve pressure and decrease friction during movement.

    • Examples: Prepatellar, olecranon, subacromial, and trochanteric bursae.

    • Bursitis: Inflammation of a bursa sac.

GERONTOLOGIC CONSIDERATIONS

  • Effects of Aging on the Musculoskeletal System:

    • Functional problems arise due to the aging process:

    • Decreased bone density, increasing risk for osteopenia and osteoporosis.

    • Decreased muscle mass and strength.

    • Decreased flexibility.

    • Increased risk for osteoarthritis.

    • Increased risk for falls.

    • Changes in proprioception influencing awareness of self in relation to the environment.

ASSESSMENT OF MUSCULOSKELETAL SYSTEM (1 OF 10)

  • Subjective data:

    • Health history

    • Medications

    • Previous surgeries or other treatments

ASSESSMENT OF MUSCULOSKELETAL SYSTEM (2 OF 10)

  • Subjective data (Cont’d):

    • Functional health patterns, including:

    • Health perception–health management pattern

    • Nutritional–metabolic pattern

    • Elimination pattern

    • Activity–exercise pattern

ASSESSMENT OF MUSCULOSKELETAL SYSTEM (3 OF 10)

  • Subjective data (Cont’d):

    • Functional health patterns including:

    • Sleep–rest pattern

    • Cognitive–perceptual pattern

    • Self-perception–self-concept pattern

ASSESSMENT OF MUSCULOSKELETAL SYSTEM (4 OF 10)

  • Subjective data (Cont’d):

    • Functional health patterns including:

    • Role–relationship pattern

    • Sexuality–reproductive pattern

    • Coping–stress tolerance pattern

    • Value–belief pattern

ASSESSMENT OF MUSCULOSKELETAL SYSTEM (5 OF 10)

  • Objective data:

    • Physical assessment entails:

    • General overview through inspection

    • Palpation

    • Motion assessment

ASSESSMENT OF MUSCULOSKELETAL SYSTEM (6 OF 10)

  • Objective data:

    • Measurement of joint angles using a goniometer for assessing range of motion.

ASSESSMENT OF MUSCULOSKELETAL SYSTEM (7 OF 10)

  • Objective data:

    • Muscle-strength Testing:

    • 0/5: No detection of muscular contraction.

    • 1/5: Barely detectable flicker or trace of contraction with observation or palpation.

    • 2/5: Active movement of body part with gravity eliminated.

    • 3/5: Active movement against gravity only, without resistance.

    • 4/5: Active movement against gravity and some resistance.

    • 5/5: Active movement against full resistance without evident fatigue (normal muscle strength).

ASSESSMENT OF MUSCULOSKELETAL SYSTEM (8 OF 10)

  • Objective data involves additional physical examination:

    • Limb length measurement

    • Circumferential muscle mass measurement

    • Assessment of posture and gait

    • Check for scoliosis

    • Straight-leg-raising test

ASSESSMENT OF MUSCULOSKELETAL SYSTEM (9 OF 10)

  • Scoliosis Assessment:

    • Evaluation includes noting any curvature of the spine or asymmetries.

ASSESSMENT OF MUSCULOSKELETAL SYSTEM (10 OF 10)

  • Normal Physical Assessment of the Musculoskeletal System:

    • Presence of normal spinal curvatures

    • Absence of muscle atrophy or asymmetry

    • No joint swelling, deformity, or crepitation

    • No tenderness upon palpation of joints, spine, or muscles

    • Full range of motion of all joints without pain or laxity

    • Muscle strength of 5/5 (normal)

DIAGNOSTIC STUDIES OF THE MUSCULOSKELETAL SYSTEM (1 OF 5)

  • Serologic Studies:

    • Aldolase

    • Alkaline phosphatase

    • Anti-cyclic citrullinated peptide (anti-CCP)

    • Anti-DNA antibody

    • Antinuclear antibody (ANA)

    • Calcium levels

DIAGNOSTIC STUDIES OF THE MUSCULOSKELETAL SYSTEM (2 OF 5)

  • Serologic Studies (Cont’d):

    • C-reactive protein

    • Creatine kinase (CK)

    • Human leukocyte antigen (HLA)-B27

    • Potassium levels

    • Phosphorus levels

    • Rheumatoid factor (RF)

DIAGNOSTIC STUDIES OF THE MUSCULOSKELETAL SYSTEM (3 OF 5)

  • Diagnostic Imaging:

    • Standard x-ray: Most common imaging method.

    • Bone scan: Used for detecting abnormal bone metabolism.

    • Computed Tomography (CT) scan: Provides cross-sectional imaging of the body.

    • Diskogram: Imaging of the intervertebral disks.

    • Dual Energy X-ray Absorptiometry (DEXA): Measures bone density.

DIAGNOSTIC STUDIES OF THE MUSCULOSKELETAL SYSTEM (4 OF 5)

  • Diagnostic Imaging (Cont’d):

    • Electromyogram (EMG): Measures muscle electrical activity.

    • MRI: Magnetic resonance imaging for detailed imaging of soft tissues.

    • Myelogram with or without CT: Imaging of the spinal canal and nerve roots.

    • Somatosensory Evoked Potential (SSEP): Measures the electrical activity of the brain in response to stimuli.

    • Thermography: Measures heat radiation from the body to detect inflammation.

    • Quantitative Ultrasound (QUS): Evaluates bone density and quality.

DIAGNOSTIC STUDIES OF THE MUSCULOSKELETAL SYSTEM (5 OF 5)

  • Interventional Studies:

    • Arthrocentesis: Procedure for removing fluid from a joint.

    • Arthroscopy: Minimally invasive procedure for examining the interior of a joint.

AUDIENCE RESPONSE QUESTION (1 OF 2)

  • Question: The nurse is caring for a 74-year-old woman. What would be a normal age-related finding?

    • A. Kyphosis

    • B. Back pain

    • C. Loss of height

    • D. Spinal crepitation

    • Answer: C. Loss of height

AUDIENCE RESPONSE QUESTION (2 OF 2)

  • Question: The nurse notices that a patient has an altered gait. To further assess this problem, which action should the nurse take?

    • A. Measure the length of both legs.

    • B. Perform deep palpation of the hip joints.

    • C. Perform muscle-strength testing of the legs.

    • D. Test range of motion of the lower extremities.

    • Answer: A. Measure the length of both legs.

AUDIENCE RESPONSE QUESTION (1 OF 2)

  • Question: The nurse is providing discharge teaching to a patient who had a myelogram. What would the nurse include in the teaching plan?

    • A. Take acetaminophen (Tylenol) to prevent a fever.

    • B. Remain flat in bed for 24 to 48 hours to prevent pain.

    • C. Decrease fluid intake for 4 to 8 hours to prevent nausea.

    • D. Report a headache that is worse when sitting or standing.

    • Answer: D. Report a headache that is worse when sitting or standing.

AUDIENCE RESPONSE QUESTION (2 OF 2)

  • Question: [As asked above]

  • Answer: D. Report a headache that is worse when sitting or standing.

STRUCTURES AND FUNCTIONS OF THE MUSCULOSKELETAL SYSTEM

  • Composition:

    • Voluntary muscle: Also known as skeletal muscle.

    • Connective tissue: Includes specialized types like bone and cartilage.

    • Bone: The rigid framework of the body.

    • Cartilage: Flexible connective tissue found in joints, ears, and nose.

    • Ligaments: Fibrous blocks that connect bone to bone.

    • Tendons: Fibrous cords that connect muscle to bone.

    • Fascia: Sheaths of connective tissue surrounding muscles and organs.

    • Bursae: Fluid-filled sacs that reduce friction.

  • Purposes:

    • Protect body organs: For example, the skull protects the brain and the rib cage protects the heart and lungs.

    • Provide support and stability: Maintains the body's shape and upright posture.

    • Store minerals: Acts as a reservoir for calcium and phosphorus.

    • Allow coordinated movement: Interaction between bones and muscles facilitated by the nervous system.

    • Hematopoiesis: The production of blood cells occurring in the red bone marrow.

BONE FUNCTIONS

  • Support: Provides a framework for the attachment of soft tissues and organs.

  • Protect internal organs: Shields sensitive structures from trauma.

  • Enable voluntary movement: Acts as levers that are pulled by muscles.

  • Blood cell production: Occurs in epiphyses of long bones and in flat bones.

  • Mineral storage: Maintains homeostasis of calcium (Ca^{2+}) and phosphate (PO_{4}^{3-}) levels in the blood.

MICROSCOPIC STRUCTURE

  • Cortical Bone (Compact):

    • Dense, hard outer layer that provides strength.

    • Osteons (Haversian systems): Functional units consisting of concentric circles of bone matrix (lamellae).

    • Haversian Canal: Central canal containing blood vessels and nerves.

    • Canaliculi: Tiny channels connecting lacunae, allowing nutrients to reach osteocytes.

  • Cancellous Bone (Spongy):

    • Lattice-like structure called trabeculae.

    • Highly vascular; contains either red marrow (hematopoietic) or yellow marrow (adipose tissue storage).

  • Bone Cells:

    • Osteoblasts: Cells that lay down new bone matrix (ossification). They are regulated by hormones like Calcitonin.

    • Osteocytes: Former osteoblasts trapped in the matrix that monitor and maintain bone tissue health.

    • Osteoclasts: Multinucleated cells that dissolve bone (resorption). They are stimulated by Parathyroid Hormone (PTH) when blood calcium is low.

GROSS STRUCTURE OF LONG BONES

  • Epiphyses: The bulbous ends composed of spongy bone covered by a thin layer of compact bone.

  • Diaphysis: The shaft, containing the medullary cavity filled with yellow marrow in adults.

  • Metaphysis: The narrowing portion where the diaphysis meets the epiphysis.

  • Epiphyseal Plate: Known as the "growth plate" in children; it becomes the epiphyseal line once growth stops.

  • Periosteum: A double-layered membrane. The outer layer is fibrous, while the inner layer contains osteoblasts for bone growth and repair.

  • Endosteum: Delicate membrane lining the internal bone surfaces (medullary cavity).

JOINTS (ARTICULATIONS)

  • Functional Classification:

    • Synarthroses: Immovable joints (e.g., sutures of the skull).

    • Amphiarthroses: Slightly movable joints (e.g., pubic symphysis).

    • Diarthroses: Freely movable joints (synovial joints).

  • Synovial Joint Components:

    • Synovial Fluid: Lubricates the joint, provides nutrients to articular cartilage, and acts as a shock absorber.

    • Joint Capsule: A tough, fibrous envelope that binds the bones together.

    • Synovial Membrane: The internal lining of the capsule that secretes the fluid.

TYPES OF DIARTHRODIAL JOINTS AND MOVEMENTS

  1. Hinge Joint: Permits movement in one plane (flexion/extension). Examples: Knee, Elbow.

  2. Ball and Socket: Permits movement in multiple axes. Examples: Hip, Shoulder.

  3. Pivot Joint: Allows rotation around a central axis. Example: Proximal radioulnar joint.

  4. Condyloid Joint: Allows movement in two planes (flexion/extension, abduction/adduction). Example: Wrist.

  5. Saddle Joint: Each surface has both concave and convex areas. Example: Thumb (1^{st} carpometacarpal joint).

  6. Gliding Joint: Flat surfaces slide past each other. Example: Intercarpal joints.

MUSCLE PHYSIOLOGY AND STRUCTURE

  • Microscopic Anatomy:

    • Sarcomere: The contractile unit between two Z-lines.

    • Sliding Filament Theory: Myosin (thick) filaments bind to Actin (thin) filaments using ATP to pull them toward the center of the sarcomere, shortening the muscle.

  • Types of Contractions:

    • Isometric: Tension is generated, but the muscle does not change length (e.g., pushing against a wall).

    • Isotonic: Muscle changes length to move a load.

      • Concentric: Muscle shortens.

      • Eccentric: Muscle lengthens under tension.

  • Neuromuscular Junction (NMJ):

    • The point of communication between a motor neuron and a muscle fiber.

    • Acetylcholine (ACh): The neurotransmitter released into the synaptic cleft.

    • Cholinesterase: An enzyme that breaks down ACh to stop the contraction.

ENERGY METABOLISM

  • ATP: The primary "energy currency."

  • Creatine Phosphate: Provides a rapid source of high-energy phosphate to regenerate ATP during the first few seconds of exercise.

  • Glycogen: Stored glucose in the muscle used for anaerobic or aerobic metabolism.

  • Lactic Acid: A byproduct of anaerobic metabolism that can lead to muscle fatigue and soreness.

ASSESSMENT OF THE MUSCULOSKELETAL SYSTEM

  • Subjective Data:

    • PQRST Assessment: Provocation, Quality, Region/Radiation, Severity, Timing of any pain.

    • Functional Impact: How do symptoms affect Activities of Daily Living (ADLs)?

  • Objective Data:

    • Inspection: Look for symmetry, alignment, and deformities (e.g., genu valgum/knock-knees or genu varum/bow-legs).

    • Palpation: Check for warmth, edema, and crepitation (a grating sound or sensation produced by friction between bone and cartilage).

    • Gait Analysis: Observe the stance and swing phases.

    • Muscle Strength Grading (0-5 Scale):

      • 5: Normal strength against full resistance.

      • 0: Total paralysis.

    • Neurovascular Assessment (The 6 Ps): Pain, Pallor, Pulselessness, Paresthesia, Paralysis, Poikilothermia (coolness). This is critical for assessing limb-threatening conditions like Compartment Syndrome.

DIAGNOSTIC STUDIES

  • X-rays: Primary tool for fractures or joint dislocations.

  • DEXA Scan: Gold standard for diagnosing osteoporosis by measuring Bone Mineral Density (BMD). Results are given as T-scores.

  • Arthrocentesis: Joint aspiration used to diagnose gout (crystals), infection (WBCs), or trauma (blood).

  • Electromyogram (EMG): Evaluates electrical activity in muscles; used to differentiate between nerve vs. muscle disorders.

  • Serum Calcium and Phosphorus: Often inversely related; useful for assessing metabolic bone diseases.