Chapter 1- Basic Principles of Kinesiology (book objectives)
Describe how force, torque, and levers affect biomechanical movement.
Forces provide the ultimate stimulus for movement and stabilization of the body. Torque can be considered the rotational equivalent of force, so same. Forces interact through a system of levers. Moment arms in levers convert forces into rotary torques.
Define commonly used anatomic and kinesiologic terminology.
• Anterior: Toward the front of the body • Posterior: Toward the back of the body • Midline: An imaginary line that courses vertically through the center of the body • Medial: Toward the midline of the body • Lateral: Away from the midline of the body • Superior: Above, or toward the head • Inferior: Below, or toward the feet • Proximal: Closer to, or toward the torso • Distal: Away from the torso • Cephalad: Toward the head • Caudal: Toward the feet (or "tail") • Superficial: Toward the surface (skin) of the body • Deep: Toward the inside (core) of the body • Origin: The proximal attachment of a muscle or ligament • Insertion: The distal attachment of a muscle or ligament • Prone: Describes the position of an individual lying face down • Supine: Describes the position of an individual lying face up • Sagittal plane: Divides the body into left and right halves. Typically, flexion and extension movements occur in the sagittal plane. • Frontal plane: Divides the body into front and back sections. Nearly all abduction and adduction motions occur in the frontal plane. • Horizontal (transverse) plane: Divides the body into upper and lower sections. Nearly all rotational movements such as internal and external rotation of the shoulder or hip and rotation of the trunk occur in the horizontal plane.
Describe the three biomechanical lever systems, and explain their advantages and disadvantages.
• First-class lever: axis of rotation (or fulcrum) located between the internal and external force [depends?] [ex: seesaw] • Second-class levers have an axis of rotation located at one end of the bony lever and always have an IMA that is longer than the EMA [good leverage, poor ROM ] [ex: wheelbarrow] • Third-class levers also have an axis of rotation located at one end of the bony lever. However, they always have an IMA that is smaller than the EMA [good speed and ROM, poor leverage] [ex: most body levers]
Describe the common movements of the body.
• Flexion: bone approaches the flexor surface of other bone • Extension: approximation of the extensor surfaces of two bones • Abduction: away from midline • Adduction: toward midline • Rotation: spins about longitudinal axis • Internal rotation: rotation toward mid line • External rotation: rotation away from midline • Circumduction: circular motion through two planes • Protraction: translation of bone away from midline in a plane parallel to the ground • Retraction: translation of bone toward the midline in a plane parallel to the ground • Horizontal adduction: arms brought together in horizontal plane • Horizontal abduction: arms away from midline in horizontal plane • Pronation: rotational movement of forearm, palms down • Supination: rotation of forearm, palms up • Radial deviation: hand moves laterally—toward the radius • Ulnar deviation: hand moves medially—toward the ulna • Dorsiflexion: bringing foot upward • Plantar flexion: pushing foot downward • Inversion: sole of foot face medially • Eversion: sole of foot facing laterally
Describe the arthrokinematic principles of movement.
1. Roll: Multiple points along one rotating articular surface contact multiple points on another articular surface. Analogy: A tire rotating across a stretch of pavement. 2. Slide: A single point on one articular surface contacts multiple points on another articular surface. Analogy: A stationary tire skidding across a stretch of icy pavement. 3. Spin: A single point on one articular surface rotates on a single point on another articular surface. Analogy: A rotating toy top spinning on one spot on the floor.
Differentiate between osteokinematic and arthrokinematic movement.
Arthrokinematics describes the motion that occurs between the articular surfaces of joints. Osteokinematics describes only the path of the moving bones. A door swings open in the horizontal plane (osteokinematics) about the spinning of a hinge (arthrokinematics).
Analyze the planes of motion and axes of rotation for common motions.
The axis of rotation is always perpendicular to the plane of motion. • Adduction/abduction: frontal plane, anterior-posterior axis • Flexion/extension: sagittal plane, medial-lateral axis • Internal/external rotation: horizontal/transverse plane, vertical/longitudinal axis
Explain how muscular force vectors are used to describe movement.
Vectors are used in kinesiology to represent the magnitude (length of arrow) and direction (orientation of arrowhead) of a force.
Analyze how muscular lines of pull produce specific biomechanical motions.
• Muscles with a line of pull anterior to the medial-lateral axis of rotation will produce flexion in the sagittal plane. Posterior to the medial-lateral axis of rotation produces extension in the sagittal plane. • Muscles with a line of pull passing superior or lateral to the anterior-posterior axis of rotation will produce abduction in the frontal plane. A line of pull that courses inferior and medial relative to the anterior-posterior axis of rotation produces adduction in the frontal plane. • Lines of pull about a vertical axis are tricky. Anterior deltoid produced internal rotation about a vertical axis. Posterior deltoid has a line of pull that produces external rotation of the shoulder.
