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Sagittal
splits body into left and right
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What actions occur in the sagittal plane?
flexion and extension
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Frontal plane:
splits the body into front and back
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Transverse plane:
splits the body into tops and bottoms
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What actions occur in the frontal plane?
abduction and adduction
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What actions occur in the transverse plane?
internal/external rotation
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Each plane is oriented in relation to the body,
not to the world. When the body or any of its segments change position, the planes change their orientation along with them
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axis
a line that is perpendicular to the plane
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Plane: Sagittal
Axis:
lateral
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Plane: sagittal
Movement:
flexion and extension
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Plane: sagittal
Special class:
hyperextension; dorsiflexion and plantar flexion of ankle
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Plane: frontal
Axis:
anterior-posterior
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Plane: frontal
Movement:
abduction/adduction
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Plane: frontal
special class:
fingers/toes; ulnar and radial deviation of wrist
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Plane: transverse
Axis:
longitudinal (or vertical)
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Plane: transverse
Movement:
rotation
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Plane: transverse
Special class:
horizontal abduction and adduction
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Plane: Multi-planar
Axis:
oblique
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Plane: Multi-planar
Movement:
pronation/supination
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Plane: Multi-planar
Special Class:
subtalar joint; midtarsal joint; radio-ulnar joint
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Open Chain Joint Movements:
- proximal joint is fixed or stable while the distal joint moves
- reaching to grasp an object in space or kicking a ball
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Closed Chain Joint Motion:
- distal joint is fixed or stable, and proximal joint moves
- stance phase of walking and rising from chair or performing a pull-up
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Mass:
- the property of matter that causes it to have weight in a gravitational field
- F=ma
- m=F/a
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Are weight and mass the same?
no
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What is weight?
an example of a FORCE, specifically, the force of gravity acting at or near the surface of the Earth
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Weight is a gravitational force that is the product of:
- a mass and a constant gravitational acceleration (g)
- W=mg
- g=32ft/sec2 or 9.8mt/sec2
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Center of Mass (Center of Gravity [COG])
(geometric) point around which every particle of a body's mass is equally distributed. A body behaves as if its entire mass acts or is acted upon at its center of gravity
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COG located at:
sacral promontory, anterior to S2 (PSIS), at 55% of body height
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Superincumbent mass:
therapists often analyze weight-bearing activities where, for example, a person stands and controls a mass atop the hip joint
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The COG of the entire lower extremity, the body segment that lies distal to the hip joint, is located just proximal to the:
knee
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With a large mass, is the joint more stable or mobile?
stability
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With a low position of center of gravity, is the joint more stable or mobile?
stable
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With a small mass, is the joint more stable or mobile?
mobile
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With a large base of support (BOS), is the joint more stable or mobile?
stable
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With a vertical projection of COG to a point near the boundary of the BOS, is the joint more stable or mobile?
mobile
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With a high position of center of gravity, is the joint more stable or mobile?
mobile
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With a small base of support, is the joint more stable or mobile?
mobile
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With a vertical projection of COG to a point near the center of BOS, is the joint more stable or mobile?
stable
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What are the three major types of joints?
- fibrous
- cartilaginous
- synovial
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Fibrous joints
- synarthroses; immobile
- ex: sutures b/w bones in skull
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Cartilaginous joints
- amphiarthroses; slightly moveable
- ex: disc articulations b/w bones in vertebral column; symphysis pubis; inferior tibiofibular joint
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Synovial joints
- diarthroses; freely movable
- permit relatively free movement b/w body segments
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Name the types of synovial joints:
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Name the uniaxial synovial joints:
- ginglymus (hinge)
- trochoid (pivot)
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Ginglymus (Hinge):
interphalangeal joints; elbow
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Trochoid (Pivot):
proximal radio-ulnar joint
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Name the biaxial synovial joints:
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Saddle:
carpal-metacarpal joint of the thumb
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Name the triaxial synovial joints:
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Ball and socket:
gleno-humeral joint, hip joint
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Planar:
facet joints in spine
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What are some features of synovial joints?
- two bones whose articular surfaces are covered with hyaline cartilage
- joint space enclosed by a fibrous capsule
- synovial membrane lining joint space
- has position(s) in its joint range of motion where the joint space's volume is at a minimum, and the joint is close-packed
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What does the synovial membrane lining a synovial joint secrete?
synovial fluid, which fills the joint space and provides lubrication and nourishment to the articular cartilage
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What is a closed packed position of a synovial joint?
- each synovial joint has a point in its range of motion where:
- its surfaces are maximally congruent
- its capsule and ligaments are maximally elongated and taut
- its surfaces are maximally compressed
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Points in the range of motion that are not close-packed positions are:
"loose-packed positions"
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Is the joint more stable in close-packed or loose-packed positions?
close-packed: more stable and least mobile
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Osteokinematics:
study of gross movements of bones and joints
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Arthrokinematics:
- study of small amplitude motions of bones at joint surface:
- roll
- glide (or slide)
- spin
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Arthrokinematics:
general term for specific movements of joint surfaces. Normal joint surface movement is necessary to ensure long-term joint integrity
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What can "roll" of arthrokinematics be compared to?
rolling of a tire on a surface
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What can "glide" of arthrokinematics be compared to?
tire slipping without rolling
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What would happen if the moving joint surface rolls on its partner without simultaneously gliding?
the surfaces would separate in some places and impinge in others
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What produces roll and glide motions?
forces
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Movements at joint surfaces (arthrokinematics) follow the rules of:
- concavity and convexity
- each joint or articulation involves two bony surfaces, one that is convex and one that is concave
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When the concave surface is fixed and the convex surface moves on it, the conves surface rolls and glides in:
opposite directions
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When the convex surface is fixed and the concave surface moves on it, the concave surface rolls and glides in:
the same direction
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