Joint Classifications and Axial Skeleton Lecture Notes

Assessment Strategy and Terminology

  • Terminology Overlap:
    • Joint classifications involve a collection of terms that sound and appear very similar.
    • Quizzes are structured intentionally with these similar terms to identify and correct points of confusion early.
    • Missing questions on a quiz serves as a learning step so that the material is answered correctly on the big test.
    • The big test is the primary target for performance because it accounts for the most points.

Functional Classifications of Joints

  • Synarthrosis (Sinothyrosis):

    • Definition: A joint that does not move (immovable joint).
    • Prefix Meaning: "Sin" (syn-) signifies no movement.
    • Primary Characteristic: Provides maximum stability and immobility.

  • Amphiarthrosis (Ampiarthrosis):

    • Definition: A joint that allows for a small amount of movement, but not very much (slightly movable joint).
    • Prefix Meaning: "Ampi" (amphi-) signifies little movement.

  • Diarthrosis:

    • Definition: A freely movable joint.
    • Functional Purpose: Facilitates wide ranges of motion necessary to carry out daily activities and tasks.

Skeletal System Functions and Anatomical Examples

  • Axial Skeleton Mechanics:

    • Core Function: Protection is the single defining function of the axial skeleton.
    • Movement Needs: Structures dedicated strictly to protection do not require movement.
    • Joint Type Association: Because the axial skeleton does not need to move, most axial skeleton bones come together at synarthrotic joints.
    • Skull Sutures: The sutures of the skull represent prime examples of synarthrotic joints. Immutability in skull sutures is essential to safeguard the brain and preserve protective structural integrity.

  • Diarthrotic Joint Locations:

    • Knee Joint: A major freely movable joint.
    • Elbow Joint: Another prime example of a freely movable joint.
    • Functional Role: Freely movable joints exist specifically to generate movement and enable a diverse repertoire of actions.

Specific Joint Movements in Anatomical Study

  • Concept of Specific Movements:
    • Joint movements required for human activity are classified technically as "specific movements."
  • Curricular Expectations:
    • Determining the precise, specific movements permitted by individual joints.
    • Mapping individual joints directly to their designated movements.
    • Providing specific anatomical examples for each category of joint movement throughout the study of the chapter.

Questions & Classroom Discussion

  • Question: "If you got some of them messed up on the quiz, I'd rather you miss it on the quiz and get it right where?"

    • Response: On the big test, because that is where the most points are earned.

  • Question: "Somebody give me an example of where one of these [synarthrosis] is found?"

    • Response: Your skull.

  • Question: "Why do you not want your sutures to move? What's the function of your axial skeleton?"

    • Direct Acknowledgment: "Thank you, miss McCann."
    • Response: Protection.

  • Question: "Do you need to move if you're protected?"

    • Response: No.

  • Question: "But diathrosis means what?"

    • Response: Freely movable.

  • Question: "So shoot me one of those [diarthrosis]?"

    • Response: Your knee joint; your elbow.

  • Question: "Why do you need some freely movable joints?"

    • Response: For movement; to do all of the things that you need to do.