Articulations And Body Movements Review Sheet

Articulations and Body Movements: Your Comprehensive Review Sheet

Understanding the architecture of human movement is foundational for anyone in health sciences, sports, fitness, or simply for anyone curious about how their own body works. This review sheet distills the complex world of articulations (joints) and body movements into a clear, structured guide. Mastery of this terminology and these concepts is not just academic; it is the language of physiotherapy, athletic training, dance, and everyday functional activity. This guide will systematically break down joint classifications, the specific movements they allow, and the clinical relevance of this knowledge, providing a solid framework for exams, practical application, and deeper anatomical literacy.

1. Foundational Classifications of Articulations (Joints)

Joints are categorized based on two primary criteria: their structural composition (what they are made of) and their functional capacity (how much movement they permit). A complete review must internalize both systems.

A. Structural Classification (Based on Tissue & Presence of a Synovial Cavity)

This is determined by the material connecting the bones and whether a fluid-filled space exists.

• Fibrous Joints: Bones are connected by dense connective tissue (collagen). No joint cavity. Generally immovable or slightly movable.
  • Examples: Sutures of the skull (synarthrosis), syndesmoses (distal tibia/fibula), gomphoses (teeth in sockets).
• Cartilaginous Joints: Bones are connected by cartilage. No joint cavity. Allow limited movement.
  • Synchondroses: Hyaline cartilage only (e.g., epiphyseal plates in growing long bones, first sternocostal joint).
  • Symphyses: Hyaline cartilage on bone ends, with a fibrocartilage pad in between (e.g., intervertebral discs, pubic symphysis).
• Synovial Joints: The most common and movable type. Bones are separated by a synovial cavity filled with synovial fluid.
  • Key Features: Articular cartilage (hyaline) on bone ends, joint (synovial) cavity, synovial membrane (secretes fluid), articular capsule (fibrous), reinforcing ligaments, bursae, and often menisci. All movements described in this review occur at synovial joints.

B. Functional Classification (Based on Degree of Movement)

This describes the range of motion a joint permits.

• Synarthrosis: Immovable joint (e.g., cranial sutures).
• Amphiarthrosis: Slightly movable joint (e.g., symphysis pubis, intervertebral discs).
• Diarthrosis: Freely movable joint. All synovial joints are diarthroses. This is the category where the vast majority of body movements occur.

2. The Synovial Joint Family: Structures & Types

Synovial joints are further classified by the shape of their articulating surfaces, which dictates the specific movements possible. This is a critical section of any review sheet.

Crucial Note: The shoulder joint (glenohumeral) has the greatest range of motion due to its shallow socket, sacrificing stability. The hip joint is deep and reinforced by strong ligaments, prioritizing stability for weight-bearing.

3. The Lexicon of Body Movements: Anatomical Position as the Reference

All movement terms describe motion from the anatomical position (standing upright, facing forward, arms at sides, palms facing forward). Movements are often paired as opposites.

A. Uniaxial Movements (Occur in 1 Plane)

• Flexion: Decreasing the angle between two bones. Think bending.
  • Examples: Bending elbow, knee, or vertebral column forward.
• Extension: Increasing the angle between two bones, returning from flexion. *Think

straightening the elbow or standing up from a bent knee.

• Rotation: Pivotal movement around a single longitudinal axis. This is the only movement possible at a pivot joint.
  • Examples: Turning the head "no" (atlantoaxial joint), rotating the forearm to palm up or down (proximal radioulnar joint).

B. Biaxial Movements (Occur in 2 Planes)

These movements occur in the sagittal and frontal planes.

• Abduction: Moving a body part away from the midline of the body.
  • Examples: Raising the arm or leg to the side.
• Adduction: Moving a body part toward the midline of the body.
  • Examples: Lowering the arm back to the side, bringing the knees together.
• Circumduction: A circular or cone-shaped movement that combines flexion, extension, abduction, and adduction in sequence. The distal end of the moving segment describes a circle while the proximal end serves as a relatively stable pivot. This is only possible at condyloid, saddle, and ball-and-socket joints.
  • Examples: Swinging the arm in a full circle, describing a circle with the leg while standing on one foot.

C. Multiaxial & Specialized Movements

These occur at the highly mobile ball-and-socket joints and involve rotation around a third axis.

• Medial (Internal) Rotation: Rotating a body part toward the midline.
  • Examples: Turning the arm so the palm faces backward, rotating the thigh inward.
• Lateral (External) Rotation: Rotating a body part away from the midline.
  • Examples: Turning the arm so the palm faces forward, rotating the thigh outward.
• Supination: A specialized forearm rotation where the palm faces anteriorly (or upward when the elbow is flexed). The radius and ulna are parallel.
• Pronation: A specialized forearm rotation where the palm faces posteriorly (or downward). The radius crosses over the ulna.
• Opposition: The movement that brings the thumb to touch the pads of the fingers on the same hand. This is a combination of flexion, abduction, and medial rotation at the unique saddle joint of the thumb, a key movement for human dexterity.
• Inversion & Eversion: Specific to the foot at the talocrural and intertarsal joints.
  • Inversion: Turning the sole medially (inward).
  • Eversion: Turning the sole laterally (outward).
• Dorsiflexion & Plantar Flexion: Also specific to the foot/ankle.
  • Dorsiflexion: Flexing the ankle so the dorsum (top) of the foot moves toward the shin (toes up).
  • Plantar Flexion: Extending the ankle so the plantar surface (sole) moves downward (pointing toes, standing on tiptoes).
• Protraction & Retraction: Moving a body part anteriorly (forward) and posteriorly (backward) in the transverse plane.
  • Examples: Jutting the jaw forward (protraction), pulling it back (retraction); rounding the shoulders forward (protraction), squeezing shoulder blades together (retraction).
• Elevation & Depression: Moving a body part superiorly (upward) and inferiorly (downward).
  • Examples: