Applied Anatomy & Kinesiology LEC - Prelim Notes

Course Overview

• Focus on understanding human movement and forces affecting the body for injury prevention, functional restoration, and performance optimization.

Kinesiology

• The study of human movement emphasizes beauty and scientific principles of motion.

Cardinal Planes

• Reference Position: Standard anatomical position where body parts are oriented forward, palms facing forward, and fingers extended.

Three Cardinal Planes

• Frontal (Coronal) Plane:

  • Divides body into front and back.
  • Motion includes abduction/adduction at joints.

• Sagittal (Midsagittal) Plane:

  • Divides body into left and right.
  • Motion includes flexion/extension and dorsiflexion/plantarflexion.

• Transverse (Horizontal) Plane:

  • Divides body into upper and lower parts.
  • Motion includes medial/lateral rotation, pronation/supination, and eversion/inversion.

Kinematics and Kinetics

• Kinematics: Study of motion without considering forces, divided into osteokinematics and arthrokinematics.
• Kinetics: Focuses on forces producing or resisting movement.

Degrees of Freedom

• Joints can move in multiple planes with maximal freedom found in shoulder and hip joints (three degrees).

Types of Motion

• Translatory Motion: Motion along or parallel to an axis (e.g., elevator moving straight).
• Curvilinear Motion: Object travels in a curved path (e.g., tossing a ball).
• Rotary (Angular) Motion: Occurs around an axis (e.g., spinning on a turntable).

Kinematic Chains

• Open Kinematic Chain (OKC): Distal segment moves independently in space (e.g., kicking a ball).
• Closed Kinematic Chain (CKC): Distal segment is fixed, requiring proximal segments to move (e.g., push-ups).

Arthrokinematics

• Examines movements between articulating joint surfaces, vital for normal joint function.

Joint Surfaces

• Ovoid Surface: Common in synovial joints where concave and convex relationships impact movement.
• Sellar Surface: Features both convex and concave surfaces (e.g., thumb joint).

Positional Terms

• Open Pack Position: Joint surfaces are not congruent, allowing for slack.
• Close Packed Position: Joint surfaces fit perfectly, promoting stability and requiring less muscular force to maintain position.

Forces in Motion

• Newton's Laws of Motion:
  • First Law: A body at rest remains at rest unless acted upon; motion remains constant unless affected by an external force.
  • Second Law: Acceleration is proportional to net forces acting on an object and inversely proportional to its mass.
  • Third Law: For every action, there is an equal and opposite reaction.

Levers in Motion

• Types of Levers:
  • First-Class Lever: Fulcrum between force and resistance (e.g., neck joint).
  • Second-Class Lever: Resistance between force and fulcrum (e.g., wheelbarrow).
  • Third-Class Lever: Force between fulcrum and resistance, common in the human body, allowing greater range of movement.

Force Vectors

• Characteristics include magnitude and direction; they can be combined to determine resultant forces acting on the body or segments.

Torque

• Defined as the effectiveness of a force in producing rotation, calculated as the product of force and distance to the axis of motion.

Significance of Motion Dynamics

• Understanding forces, degrees of freedom, and motion types is crucial for analyzing human movement and developing efficient movement strategies in clinical practice and sports science.### Muscle Fiber Types
• Muscles may consist of varying proportions of type I (slow twitch) and type II (fast twitch) fibers, which can change due to activity levels and hormone influences over a lifetime.
• Type I fibers resist fatigue and support sustained activities, while type II fibers produce rapid force and power but have lower endurance.

Muscle Function and Roles

• Agonist: The prime mover muscle responsible for a specific action.
• Antagonist: Opposes the action of the agonist, often inactive during the primary activity to allow movement.
• Synergist: Assists the agonist in performing an action and stabilizes other muscles.

Muscle Characteristics

• Viscosity: Resistance of muscle tissue to deformation; reducing temperature increases viscosity, while applying heat decreases it.
• Elasticity: The ability to stretch and return to original shape; more elastic tissues have greater extensibility but lower viscosity.
• Extensibility: Ability to stretch; greater extensibility results in less viscosity.

Stress-Strain Curve

• Toe region: Tissue displays a crimped appearance, taking up slack under stress.
• Plastic range: Results in permanent tissue change; continued stress leads to micro-ruptures.
• Creep: The gradual elongation due to a sustained low-level load.

Muscle Strength Factors

• Influenced by muscle size, architecture, passive components, moment arm length, and speed of contraction.
• Larger cross-sectional muscles generate greater force and can experience hypertrophy with exercise or atrophy with inactivity.

Length-Tension Relationships

• Muscles demonstrate optimal tension at resting length; active tension declines when muscles shorten past optimal length due to fewer actin-myosin cross bridges.

Gender and Age Differences

• Males typically possess greater muscle mass post-puberty, leading to about 50% more muscle mass than females.
• Muscle strength peaks between ages 20-30 and declines thereafter, with developmental differences between genders.

Active and Passive Insufficiency

• Active insufficiency occurs when a multijoint muscle is at its shortest length, preventing effective force production.
• Passive insufficiency arises when a muscle is stretched over multiple joints, limiting shortening potential.

Exercise-Induced Muscle Injury

• Delayed-onset muscle soreness (DOMS) typically begins 24 hours post-activity, lasting up to 10 days, potentially reducing range of motion and force output significantly.

Shoulder Complex Anatomy

• Composed of 20 muscles, 3 bony articulations, and 3 soft tissue surfaces, enabling extensive mobility.
• Functions include stabilizing the glenohumeral joint, allowing diverse hand placements, and facilitating body elevation and respiration.### Shoulder Girdle Structure
• Manubrium connects left and right clavicles to the axial skeleton.
• Glenoid fossa faces anteriorly, tilted 30° to 45° from the frontal plane; significantly affects shoulder movement.
• Scapula is tipped 10° to 20° in the sagittal plane, with the superior aspect more anterior than the inferior angle.

Clavicle Characteristics

• S-shaped and slightly elevated at 20° to the frontal plane, acts as a lateral strut to enhance glenohumeral mobility.
• Ends of the clavicle: convex at the sternal end, concave at the acromial end; contributes to shoulder range of motion.

Humeral Head Positioning

• Positioned medially and superiorly in the frontal plane, with a posterior rotation in the transverse plane.

Movements of the Shoulder Girdle

• Elevation: Scapula slides upward; clavicle elevates about 60° at the SC joint.
• Depression: Scapula moves downward; minimal range (5° to 10°) from seated position.
• Protraction (Scapular Abduction): Scapula moves anteriorly; lateral border extends 5-6 inches (13-15 cm) from the midline.
• Retraction (Scapular Adduction): Scapula moves posteriorly towards the midline.

Joint Types in the Shoulder Girdle

• True Joints:

  • Sternoclavicular (SC) Joint: Connects upper extremity with the axial skeleton; has 3 degrees of freedom.
  • Acromioclavicular (AC) Joint: 3 degrees of freedom, facilitating shoulder mobility.
  • Glenohumeral (GH) Joint: Major ball-and-socket joint providing extensive range of motion.

• False/ Pseudo Joint:

  • Scapulothoracic Joint: Lacks bony articulation; relies on soft tissue connections.

Sternoclavicular Joint Mechanics

• Acts as a strut with elevation and depression movements occurring in the frontal plane.
• Elevation: clavicle moves upward-backward (30-45°), limited by costoclavicular ligament and subclavius.
• Depression: clavicle moves forward-downward (5-10°), limited by interclavicular and superior capsule ligaments.
• Arthrokinematics involve the convex shape of the clavicle rolling and sliding; stability provided by ligaments.

Acromioclavicular Joint Mechanics

• Plane joint allowing 3 degrees of freedom; medial face of acromial end helps accommodate arm movements.
• Facilitates dynamic movement of the shoulder, enhancing function during activities requiring arm mobility.