Axis and Planes of Motion

Axis and planes of motion

• Axis of rotation is an imaginary or real point around which movement occurs
• Planes of motion are imaginary flat surfaces that pass through the body

Sagittal Plane

• It is a vertical plane that divides the body into equal right and left halves
• It works on the medial and lateral axis
• Movements in this plane include flexion, extension, hyperextension, dorsiflexion, and plantar flexion

Frontal Plane

• Divides the body into anterior and posterior halves
• It works on the anterior and posterior axis
• Movements include abduction, adduction, inversion, eversion, and lateral flexion of the trunk

Horizontal Plane

• Divides the body into superior and inferior halves
• It works on the longitudinal axis
• Movements include medial rotation, lateral rotation, supination, pronation, horizontal abduction, and horizontal adduction

Oblique Plane

• Includes movements that occur in two or more planes
• Opposition of the thumb and circumduction of the shoulder

Types of Joints

• Joints are composed of two or more bones that come close to each other via ligaments or cartilage
• There are different types of joints

Fibrous Joints (Immovable)

• Held firmly together by thin layers of connective tissue
• There is no movement between the bones like skull joints

Cartilaginous Joints

• The articular surfaces of bone are attached by fibrocartilaginous ligaments
• Allows limited or partially movement like joints between vertebrae

Synovial Joints (Freely Movable Joints)

• Distinct characteristics of these joints

  • The two ends of bones are covered by smooth cartilage to reduce friction
  • The joint is enclosed by a capsular ligament
  • The capsular ligament is lined with a synovial membrane
  • The synovial membrane secretes synovial fluid, which acts as waterproofing, lubricates joints, and absorbs shock
  • The joint is covered by strong ligaments and connective tissue for normal ROM and to prevent dislocation

Types of Synovial Joints

• Ball and socket: shoulder and hip joints
• Hinge joint: concave and convex surfaces such as the elbow and knee
• Gliding joint: Allows gliding movement between bones such as the carpal and tarsal bones
• Pivot joint: One bone rotates around another like the radioulnar joint
• Saddle joint: like riding a horse, joint of the thumb

Types of Muscle Fibers

• Skeletal muscles are voluntary muscles which facilitates joint movement

Slow Twitch Muscle Fibers (Type 1)

• These fibers efficiently use O₂ to generate fuel
• They fire slowly compared to type 2
• Highly resistant to fatigue
• Useful in endurance activities and sports
• Have a red color due to a high amount of myoglobin and mitochondria

Fast Twitch (IIa)

• Transitional fibers between type 1 and type IIb, having a pink color
• Intermediate resistance to fatigue
• Responsible for rapid movements like jumping
• They produce more muscular force and strength

Fast Twitch (IIb)

• Low resistance to fatigue
• Responsible for rapid movement
• Recruited for max strength
• White in color
• The type of fibers used depends on the goal of the exercise; endurance uses type 1, and strength uses type 2

Types of Muscle Contractions

• Muscle contraction means producing tension in the muscle

Static Contraction

• The muscle contracts without movement in the joint and without resistance

Isometric Contraction

• The muscle contracts without movement in the joint, against resistance, which makes more tension without a change in length

Isotonic Contraction

• The muscle contracts with movement in the joint

Concentric Contraction

• Tension in the muscle with shortening of muscle fibers
• The origin and insertion close together

Eccentric Contraction

• Tension in the muscle with lengthening of the muscle fibers
• The origin and insertion move away from each other

Isokinetic Contraction (Constant Speed)

• This type of contraction is done with isokinetic equipment to test and improve strength and endurance
• Controlling resistance and speed helps to:
  • Prevent injury
  • Increase muscle flexibility
  • Control muscle development

Co-operating Muscle Groups

• Agonists (prime movers): the main muscles responsible for movement
• Antagonists: the group of muscles opposite the agonists, responsible for relaxation
• Synergists: assist the agonists to perform normal ROM
• Fixators: provide support to the body during movement and are called stabilizers