Joints and Muscles Quiz

Joints and Muscles

• Joints connect bones, enabling movement
• Muscles cause movement by contracting, pulling on bones

Joint Classification

• Fibrous joints: Immobile or slightly mobile; bones joined directly (e.g., skull sutures)
• Cartilaginous joints: Slightly movable; bones connected by cartilage (e.g., ribs to sternum)
• Synovial joints: Freely movable; bones separated by a fluid-filled cavity (e.g., knee, shoulder) and have a capsule surrounding the joint

Synovial Joints

• Synovial joints have an articular capsule composed of an outer fibrous layer and inner synovial membrane.
• The synovial membrane secretes synovial fluid to lubricate the joint, reducing friction
• Cartilage covers the ends of bones within the joint to cushion and reduce friction
• Ligaments strengthen the joint and stabilize it.
• Joint cavities contain synovial fluid

Types of Synovial Joints

• Ball-and-socket joints (e.g., shoulder)
• Hinge joints (e.g., elbow, knee)
• Pivot joints (e.g., atlas joint)
• Condylar joints (e.g., wrist)
• Saddle joints (e.g., thumb)
• Plane joints (e.g., intercarpal)

Anatomical Axes

• Sagittal axis: Runs from front to back.
• Vertical axis: Runs from top to bottom.
• Frontal axis: Runs from side to side.

Movement Types

• Flexion: Decreasing angle between body parts
• Extension: Increasing angle between body parts
• Abduction: Moving a limb away from the midline.
• Adduction: Moving a limb towards the midline.
• Rotation: Movement around an axis.
• Lateral flexion: Side-bending of the torso.
• Supination: The forearm rotates so the palm is facing upward.
• Pronation: The forearm rotates so the palm is facing downward.
• Inversion: Turning the sole of the foot inward.
• Eversion: Turning the sole of the foot outward.
• Dorsiflexion: Bending the foot upward.
• Plantar flexion: Bending the foot downward.

Muscles

• Myology: The study of muscles
• Skeletal muscles: Attached to bones, voluntary movement
• Smooth muscles: Found in internal organs, involuntary movement
• Cardiac muscles: Found in the heart, involuntary movement
• Muscles are classified by shape, location, and function.
• Muscles are composed of muscle fibers
• Attachments of muscles to bones are via tendons/aponeurosis

Muscle Contraction

• Muscle actions lead to movement.
• Skeletal muscle movements occur when the muscle contracts
• Types of contractions:
  • Isometric: no change in muscle length.
  • Isotonic: change in muscle length.
• Attachments of muscles to bones define the action of the muscle.
• Muscle actions are described in terms of origin, insertion and action.

Motor Units

• A motor neuron and all the muscle fibers it controls.
• All motor units do not need to contract at the same time for a smooth muscle movement.