Musculo-Skeletal System Unit 1

Study Notes

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).

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

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.

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.

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.

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.