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Joints
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Structure determines combination of strength an flexibility
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Shape of articulating bones
Flexibility of the ligaments
Tension of associated muscles and tendons
Hormones
Structural classification
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Closer the fit = stronger joint = less movement
Movement is determined by:
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Joints
Fibrous joints
Cartilaginous joints
Synovial joints
Functional classification:
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Synarthrosis – immovable
Amphiarthrosis – slightly moveable
Diarthrosis – freely movable
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Fibrous joints
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Suture
 Composed of thin layer of dense
fibrous connective tissue
 Unite bones of skull
 Synarthrosis
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Syndesmosis
 Distance between bones and amount
of DFCT < than in a suture
 Distal articulation between the tibia
and fibula
 Amphiarthrosis
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Gomphosis
 Cone shaped peg fits into a socket
 roots of the teeth with the sockets of
the alveolar processes
 synarthrosis
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Cartilaginous joints
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Synchondrosis
 Connected by hyaline
cartilage
 Epiphyseal plate
 Synarthrosis
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Symphysis
 ends of bones are covered in
hyaline cartilage; bones are
connected by a flat disc of
fibrocartilage
 Pubic symphysis and
intervertebral joints
 amphiarthrosis
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Structure of synovial joints
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the synovial (joint) cavity
 Allows the joints to be diathroses
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Bones are covered by articular cartilage > friction
and helps absorb shock
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Articular capsule
 Surrounds joint
 Encloses synovial cavity
 Unites articulating bones
 2 layers
 Outer (fibrous capsule)- consists of DICT
that attaches to the periosteum (ligaments)
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Inner (Synovial membrane) – secretes
synovial fluid
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lube joint, supply nutrients to and
remove waste from the chondrocytes of
articular cartilage
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Continued
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Articular fat pads
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Accessory ligaments
 Inside ex: anterior and posterior cruciate
ligaments of the knee
 Outside ex: fibular (lateral) and tibial (medial)
collateral ligaments of the knee
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Articular discs (menisci)
 Pads of fibrocartilage between the surfaces of
the bones, attached to the fibrous capsule
 allow bones of different shapes to fit together
more tightly
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maintain stability of the joint , direct the
flow of synovial fluid to the areas of
greatest friction
Bursae
 Saclike structures (knee, shoulder)
 Cushion the movement of one body part over
another
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Types of movement at synovial
joints
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Gliding
 Relatively flat bone surface moves
back and forth or side – side
relative to one another
 Ex:
 Between the acromion of the
scapula and the clavicle
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Angular movements
 Flexion
 > in angle
 Extension
 < in angle
 Hyperextension
 extension beyond the
anatomical position
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Types of movement at synovial
joints
Abduction
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Movement of a bone away
from the midline
Adduction
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Movement of a bone
toward the midline of the
body
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Types of movement at synovial
joints
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Circumduction
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Movement of the distal
end of a part of the body
in a circle
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Types of movement at synovial
joints
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Rotation
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Bone revolves around its
own longitudinal axis
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Medial (internal) rotation
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Anterior surface of a bone
of the limb is turned
toward the midline
Lateral (external ) rotation
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Anterior surface of the
bone is turned away from
the midline of the body
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Types of movement at synovial
joints
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Special movements
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Elevation
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Depression
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Protraction
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Bending of the foot toward plantar surface
Supination
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Bending of the foot toward dorsum
Plantar flexion
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Movement of the soles laterally
Dorsiflexion
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Movement of the soles medially
Eversion
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Movement of a part of the body back towards
anatomical position
Inversion
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Movement of a part of the body forward
Retraction
Movement of the forearm so the palm is turned
forward (defining feature of the anatomical position)
Pronation
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Movement of the forearm so that the palm is turned
backwards
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Subtypes of synovial joints
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Planar joints
 Articulating surfaces of bones are flat
or slightly curved
 Ex: Intercarpal, intertarsal,
sternoclavicular, acromioclavicular
 Permit gliding
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Hinge joints
 Convex surface of one bone fits into
concave surface of another
 Ex: Knee, elbow, ankle, interphalangeal
 Permit flexion, extension
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Pivot joints
 Rounded or pointed surface of one
bone joins with a ring formed partly by
another bone and ligaments
 Ex: Atlantoaxial joint, radioulnar joints
 Permit rotation around its own
longitudinal axis
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Subtypes of synovial joints
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Condyloid joints
 Convexed oval-shaped projection of one bone
fits into the concave oval-shaped depression of
another bone
 Ex: Wrist, metacarpophalangeal joints digits 25
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flexion, extension, abduction, adduction,
circumduction
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Saddle joints
 surface of one bone is saddle-shaped and the
surface of the other fits into it
 Ex: carpometacarpal joint
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flexion, extension, abduction, adduction,
cirumduction
Ball-and-socket joints
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Ball-like surface of one bone fits into cuplike
depression of another
Ex: Shoulder, hip
flexion, extension, abduction, adduction,
circumduction, rotation
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The knee joint
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Main structure of the knee joint
 Articular capsule
 Patellar ligament –strengthens the
anterior surface
 Oblique popliteal ligament –
strengthens the posterior surface
 Arcuate popliteal ligament –
strengthens the lower lateral posterior
surface
 Tibeal (medial) collateral ligament –
strengthens the medial aspect
 Fibular (lateral) collateral ligament –
strengthens the lateral aspect
 Anterior cruciate ligament –
 Posterior cruciate ligament – limits
anterior/posterior movement of femur
 Medial meniscus
 Lateral meniscus
 Bursae
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Aging and joints
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> production of synovial fluid
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Articular cartilage becomes thinner
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Ligaments shorten and lose flexibility
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Influenced by genetics, wear and tear
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By 80 most everybody has some form of degeneration in
knees, elbows, hips, shoulders
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Elderly develop degenerative changes in vertebral column