Musculo-Skeletal System Unit 1

Musculo-Skeletal System Overview

• The skeletal system provides body shape, protection for internal organs, and a framework for muscle attachment facilitating movement.
• Comprised of two primary types: appendicular (extremities) and axial (skull, ribcage, vertebral column).

Bones and Cartilage

• Bone structure consists of collagen fibers infused with minerals, primarily calcium salts.

Joints

• Joints connect bones, enabling movement and stabilization.
• Movement is facilitated by the contraction of skeletal muscles across joints, typically with two attachment points on opposite sides.

Movements of Synovial Joints

• Flexion and Extension: Flexion moves a body part forward; extension moves it backward.
• Horizontal Flexion and Extension: Horizontal flexion brings the arm closer to the body; horizontal extension moves the arm away from the body.
• Abduction and Adduction: Abduction moves a body part away from the midline; adduction draws it toward the midline.
• Rotation: Involves turning a body part around its long axis.
• Circumduction: A conical movement where the end of a body part moves in a circular pattern.
• Pronation and Supination: Specific to the forearm; supination occurs in the anatomical position, while pronation refers to rotation inward.
• Lateral Flexion: Bending of the spine sideways, unique to spinal movement.
• Dorsiflexion and Plantar Flexion: Dorsiflexion brings the foot towards the shin; plantar flexion moves the foot away from the shin.

Joint Types and Movements

• Left shoulder: Ball & socket, capable of flexion.
• Right wrist: Condyloid joint, capable of extension.
• Right knee: Hinge joint, allows for extension.

Muscular System Overview

• Muscles are responsible for pulling bones to produce movement, working in pairs to create movement and return to original positions.
• Antagonistic Muscle Action: One muscle contracts (agonist) while its counterpart (antagonist) lengthens to stabilize and facilitate movement.

Muscle Types

• Agonist Muscles:

  • Prime movers (e.g., biceps, hamstrings).
  • Contract to produce movement by pulling and shortening during actions.

• Antagonist Muscles:

  • Perform the opposite action of agonists (e.g., triceps to biceps).
  • Stabilize movement by lengthening when agonists contract.

Rotator Cuff Muscles

• Key muscles include infraspinatus and subscapularis, crucial for shoulder stabilization and movement.