KinesiologyQuiz1Weeks1-3 Flashcards
Kinematics
branch of mechanics that describes the motion of a body, without regard to the forces or torque that may produce the motion
Translation vs. Rotation
Translation: linear motion in which all parts of a rigid body move parallel to and in the same direction as every other part of the body Rotation: motion in which an assumed rigid body moves in a circular path around some pivot point (axis of rotation)
Motion of the body during walking
center of mass of the human body (just anterior to the sacrum) moves in a curvilinear manner
Active vs. Passive movements
Active: caused by stimulated muscles Passive: caused by sources other than active muscle contraction i.e. gravity, tension in connective tissue, etc.
Osteokinematics
motion of bones relative to the three principal planes of the body: sagittal, frontal, and horizontal
Sagittal Plane
flexion and extension; dorsiflexion and plantar flexion; forward and backward bending
Frontal Plane
abduction and adduction; lateral flexion; ulnar and radial deviation; eversion and inversion
Horizontal Plane
internal (medial) and external (lateral) rotation; axial rotation
Axis of Rotation
bones rotate around a joint in a plane that is perpendicular to the axis of rotation, axis of rotation will shift throughout movement (imperfect sphere)
Medial-lateral (ML) axis of rotation (shoulder)
flexion and extension
Anterior-posterior (AP) axis of rotation (shoulder)
abduction and adduction
Vertical axis of rotation (shoulder)
internal and external rotation
Degrees of Freedom
number of independent movements allowed at a joint; up to 3 degrees of angular freedom at a joint (3 dimensions of space)
Accessory movements
slight passive translations that occur in most joints defined in 3 linear directions
Two perspectives of joint movement
1) proximal segment can rotate against the relatively fixed distal segment; 2) distal segment can rotate against a relatively fixed proximal segment; (knee flexion only describes relative motion)
Kinematic Chain
Open: distal segment of a kinematic chain is not fixed to the earth or other immovable object; Closed: distal segment is fixed to the earth or other immovable object; (used to describe relative segment kinematics)
Arthrokinematics
describes the motion that occurs between the articular surfaces of a joint, most surfaces are curved (convex and concave)
Fundamental movements between joint surfaces
Roll: multiple points contact multiple points; Slide: single point contacts multiple points; Spin: single point contacts single point
Convex-on-concave movement
roll and slide occur in opposite directions (abduction of shoulder)
Concave-on-convex movement
roll and slide occur in same direction (tibial-on-femoral knee extension)
Example of spin movement
radius of forearm on capitulum of humerus during pronation; internal and external rotation of the 90-degree abducted glenohumeral joint; flexion and extension of the hip
Close-packed position
position of joint’s maximal congruency, accessory motions are minimal (usually near the end range, knee’s is full extension)
Open (Loose)-packed position
all positions other than a joint’s close-packed position, accessory movements are maximal (typically at mid-range, biased toward flexion)
Kinetics
branch of mechanics that describes the effect of forces on the body
Force
a push or pull that can produce, stop, or modify movement (force is 0 when acceleration is 0 and vice versa)
Most common musculoskeletal forces
tension, compression, bending, shear, torsion, combo loading
Stress-strain curve
Small tension: collagen fibers within tissue must be drawn taut for tension to be measured; Elastic zone: initial nonlinear and subsequent linear region of the curve, tissue can return to original length if healthy; Yield point: tissue elongated beyond its physiologic range; Plasticity: behavior of an overstretched or over-compressed tissue, microscopic failure has occurred and tissue is permanently deformed ; Initial failure: tissue begins to lose ability to hold tension; Mechanical failure: tissue separates partially or completely and loses all ability to hold tension
Time load of application for stress-strain curve
Viscoelasticity: factor of time, causing curve to change; Creep: progress strain of a material when exposed to constant stress over a period of time
Internal vs. External forces
Internal: produced from structures located within the body and may be passive (gravity, tension in connective tissue) or active (muscles); External: produced by forces acting outside the body
Line of Force or Line of Gravity
direction of a muscle force and the direction of gravity
Angle of Insertion
angle formed between a tendon of a muscle and the long axis of the bone to which it inserts (changes depending on the bone’s spatial orientation)
Joint Reaction Force
force through the center of a joint, produced between the surfaces of the joint
Center of Mass
gravity always acts on this portion of the body segment
Static Linear Equilibrium
all forces equal, no movement occurs
Two outcomes of forces exerted on the body
potentially translate a body segment; if applied at some distance perpendicular to the axis of rotation, can produce a potential rotation at the joint
Moment Arm
perpendicular distance between the axis of rotation of the joint and the force
Torque
product of force and its moment arm (rotary equivalent to force)
Static Rotary Equilibrium
internal torque = external torque; internal moment = external moment; No rotation, isometric status
Types of Muscle Activation
Isometric: muscle is producing a pulling force while maintaining a constant length; Concentric: muscle produces a pulling force as it contracts (shortens), internal torque > external torque; Eccentric: muscle produces a pulling force as it is being elongated by another more dominant force, external torque > internal torque
Muscle Action at a Joint
potential to cause a torque in a particular rotation direction and plane; can occur distal-on-proximal or opposite, depending on stability; ex. posterior deltoid at glenohumeral joint adduction in frontal plane, external rotation in horizontal plane, or extension in sagittal plane
Agonist vs. Antagonist
agonist: most directly related to the initiation and execution of a particular movement, ex. biceps flexion at elbow; antagonist: opposite action of a particular agonist, ex. triceps to biceps
Synergists
cooperate during execution of a particular movement, ex. glutes and hamstrings; injury to one muscle will affect the other
Force-Couple
two or more muscles simultaneously produce forces in different linear directions, although the resultant torques act in the same rotary direction, ex. hip flexors and back extensors
Musculoskeletal Levers
First Class: axis of rotation between the opposing forces, ex. head and neck extensor muscles that control the posture of the head; Second Class: axis of rotation is located at the end of a bone, muscle (internal force) possesses greater leverage than the external force, very rare in the body, ex. calf muscles producing torque to stand on toes; Third Class: axis of rotation located at the end of a bone, external force is greater than internal force, most common, ex. biceps during elbow flexion
Mechanical Advantage
ratio of the internal moment arm to the external moment arm; MA>1 - able to balance the torque equilibrium equation by an internal force that is less than external force; MA<1 - requires greater force (most of the musculoskeletal system)
Three Classifications of Joints
Synarthrosis (fibrous): dense connective tissue, no movement, ex. sutures of skull; Ampiarthrosis (cartilaginous): hyaline or fibrocartilage, restrained movement and shock absorption, ex. intervertebral discs, SC joint; Diarthrosis (synovial joint): synovial fluid and capsular, ex. glenohumeral, IP
Composition of Diarthrodial (Synovial) Joint
synovial fluid; articular cartilage; articular capsule; synovial membrane/bursa; capsular ligaments; blood vessels; sensory nerves; may also include labrum, fat pads, plica, menisci or discs
Hinge Joint
flexion and extension; ex. humero-ulnar, interphalangeal
Pivot Joint
spinning of one member around a single axis of rotation; ex. humeroradial, atlanto-axial
Ellipsoid Joint
biplanar motion (flexion-extension and abduction-adduction); ex. radiocarpal
Ball-and-Socket Joint
triplanar motion (flexion-extension, abduction-adduction, and internal-external rotation); ex. glenohumeral, coxofemoral (hip)
Plane Joint
typical movements include slide (translation) or combined slide and rotation; ex. carpometacarpal (digits II-IV), intercarpal, intertarsal
Saddle Joint
biplanar motion; spin may be limited by interlocking nature of joint; ex. carpometacarpal of thumb, SC
Condyloid Joint
biplanar motion; either flexion-extension and abduction-adduction or flexion-extension and axial rotation (internal-external rotation); ex. metacarpophalangeal, tibiofemoral