Chapter 1 - Sports, Exercise and Health Science - Course Companion

Chapter 1: Musculoskeletal Anatomy

Introduction

  • The musculoskeletal system comprises:

    • Skeletal system: bones and joints

    • Muscular system: muscles

  • Functions of the system:

    • Enables movement by forming joints, allowing muscles to pull bones.

    • Essential for sports and daily activities.

Anatomical Terminology

  • The body is divided into segments: trunk, thigh, upper arm, etc.

  • Positions described in relation to one another:

    • Proximal: closer to the torso

    • Distal: further from the torso

    • Anterior: front side

    • Posterior: back side

    • Medial: towards the midline

    • Lateral: away from the midline

Skeletal System

  • Comprised of bones, cartilage, ligaments, and joints, accounting for ~20% of body weight.

  • Physical structure:

    • Total bones: 206

    • Axial skeleton: 80 bones (skull, vertebral column, ribs)

    • Appendicular skeleton: 126 bones (limb bones and girdles)

  • Functions:

    • Protection: skull protects brain, ribcage protects heart/lungs.

    • Support/Posture: framework for body shape.

    • Attachment for muscles: tendons link muscles to bones.

    • Mineral storage: stores calcium and phosphorus.

    • Blood cell production: site of hemopoiesis in bone marrow.

The Vertebral Column

  • Composed of 33 vertebrae, providing flexibility and support.

    • Sections: cervical (7), thoracic (12), lumbar (5), sacral (5 fused), coccygeal (4 fused).

  • Main functions:

    • Supports head and body, allows various movements (flexion, extension, rotation).

    • Protects spinal cord, transmits weight to lower limbs.

Joints

  • Definitions:

    • Joint: articulation between two bones.

    • Functions to allow movement of the body (ton of movement varies).

  • Joint stability is influenced by:

    • Shape of bones

    • Contact area

    • Ligament strength

    • Soft tissue structures (muscles, tendons).

Muscle Anatomy

  • Types of Muscle:

    • Skeletal Muscle: voluntary control, striated, primarily involved in moving joints.

    • Cardiac Muscle: involuntary, striated, makes up the heart.

    • Smooth Muscle: involuntary, non-striated, found in walls of hollow organs (stomach, intestines).

Muscle Function

  • Major functions:

    • Movement: through contraction, muscles pull on bones to create motion.

    • Support: stabilizes body positions (e.g., posture).

    • Heat Generation: muscle contractions can produce body heat.

Structure of Skeletal Muscles

  • Fascia: connective tissue that surrounds muscles.

  • Three layers surrounding a muscle:

    • Epimysium: outer layer covering the entire muscle.

    • Perimysium: surrounds bundles of muscle fibers (fascicles).

    • Endomysium: surrounds individual muscle fibers.

  • Inside muscle fibers:

    • Myofibrils: contain actin and myosin filaments responsible for contraction.

    • Sarcomeres: functional units of contraction.

Major Muscle Groups

  • Muscles of the Trunk:

    • Rectus abdominus: flexes trunk; gives six-pack appearance.

    • External oblique: involved in trunk rotation and bending.

    • Erector spinae: extends the trunk and maintains posture.

  • Upper Extremity Muscles:

    • Deltoid: shoulder muscle that allows a wide range of motion.

    • Biceps brachii: involved in elbow flexion.

    • Trapezius: stabilizes shoulder and controls scapula movement.

    • Latissimus dorsi: involved in shoulder movement and extension.

  • Lower Extremity Muscles:

    • Gluteus maximus: moves the thigh backwards (hip extension).

    • Quadriceps: straightens knee; important in jumping and kicking.

    • Hamstrings: flexes knee and extends hip.

    • Gastrocnemius: plantar flexion at the ankle, important for running and jumping.

Key Points

  • Muscles typically act in pairs (agonist and antagonist).

  • Tendons connect muscles to bone, while ligaments connect bone to bone.

  • Structure-function relationship is fundamental in understanding movement mechanics.