Skeletal System Articulations

Skeletal System Articulations

• Articulations are the junctions between bones.
• Articulations are classified by their structure and function.
• Bony Fusion (Synostosis): A fusion of bones, considered a non-moving joint (Synarthrosis), example: frontal suture fusion.
• Fibrous Joint: Bones united by fibrous connective tissue, offering limited movement (Synarthrosis or Amphiarthrosis). Subtypes include suture (skull sutures), gomphosis (tooth in jaw), and syndesmosis (distal tibia-fibula joint).
• Cartilaginous Joint: Bones united by cartilage, providing slight movement (Synarthrosis or Amphiarthrosis). Types include synchondrosis (epiphyseal plates) and symphysis (pubic symphysis).
• Synovial Joint: Characterized by a synovial cavity, allowing free movement (Diarthrosis). Subtypes include monaxial (elbow), biaxial (wrist), and triaxial (hip, shoulder).

General Description of Articulations

• Joints are classified into three structural functional categories:

  • Synarthroses (no movement): bones held together tightly. Suture, gomphosis, synchondrosis, and synostosis exemplify this category.
  • Amphiarthroses (little movement): bones with limited movement. Syndesmosis and symphysis fit into this functional category.
  • Diarthroses (free movement): bones with substantial movement, like synovial joints.

• Synovial Joints: A joint containing a synovial cavity.

  • Essential structures: joint capsule, synovial membrane, articular cartilages, and joint cavity containing synovial fluid.

• Additional structures of synovial joints: Menisci (knee), articular discs (TMJ, sternoclavicular joint), and labra (shoulder).

Types of Movements

• Linear motion (Gliding): One bone slides against another. Example: intercarpal joints.
• Angular motion: Angles between bones change, with additional subtypes like:
  • Flexion: Bending a joint.
  • Extension: Straightening a joint.
  • Abduction: Movement away from the midline.
  • Adduction: Movement towards the midline.
• Circumduction: A circular movement of a limb.
• Rotation: Movement around an axis. Subtypes include medial (internal) and lateral (external) rotation.

Special Movements

• Additional movements beyond basic motions, including:
  • Eversion: Turning the sole of the foot outward.
  • Inversion: Turning the sole of the foot inward.
  • Dorsiflexion: Bending the foot upwards.
  • Plantar flexion: Bending the foot downward.
  • Lateral flexion: Side-to-side bending of the spine.
  • Retraction: Moving a part backward.
  • Protraction: Moving a part forward.
  • Depression: Lowering a body part.
  • Elevation: Raising a body part.
  • Opposition: Moving the thumb to touch other fingers.

Representative Articulations

• Temporomandibular Joint (TMJ): The joint connecting the mandible (lower jaw) with the temporal bone (skull). Includes specific structures like articular tubercle, articular surface, articular disc, condyloid process, and various ligaments.
• Sternoclavicular Joint: The articulation where the clavicle meets the sternum.
• Shoulder Joint: The glenohumeral joint, ball-and-socket type, high range of motion but less stable.

Problems with the Intervertebral Discs

• Slipped disc: Abnormal displacement of an intervertebral disc.
• Herniated disc: A bulge or rupture of the intervertebral disc.

Articulations of the Pelvis

• Includes several joints and ligaments, playing a critical role in the stability and mobility of the pelvic girdle. Key components include sacroiliac joint, pubic symphysis and numerous ligaments (Iliolumbar, sacrotuberous, sacrospinous etc.).

Articulations of the Thoracic Cage

• Costovertebral joints: between ribs and thoracic vertebrae.
• Sternocostal joints: between ribs and sternum.
• Costochondral joints: between ribs and costal cartilage.
• Interchondral joints: between costal cartilages.

Anatomy of the Knee, Elbow, and Ankle

• Detailed descriptions of the structures composing these joints, including bones, ligaments, and other connective tissues.

Radioulnar Joints

• Articulations between the radius and ulna, significant for forearm rotation.

The Joints of the Wrist

• Articulations between the radius/ulna and carpal bones.

Hip Joint

• Detailed anatomy of hip joint components including specific ligaments and cartilage structures.

Explore the fascinating world of skeletal system articulations in this quiz. Learn about the various types of joints, including bony, fibrous, cartilaginous, and synovial joints, and their classifications. Test your understanding of how these joints influence movement and stability in the human body.