Chapter 9: Joints

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Chapter 9 Joints

• Anatomy 32

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• I. Articulations bones are rigid structures but
  become moveable at the joint or articulations
  (Greek- arthro). Joints may occur as bone to
  bone, bone to cartilage, or teeth to bone.
• A. Classification of Joints- when classified by
  function the focus is placed one the amount of
  movement. When classified by structure the focus
  is on the tissue type that makes the joint. See
  table 9.1 pg 202for structural and functional
  (mobility) characteristics.
• 1. synarthrosis- immovable
• 2. amphiarthrosis- slightly moveable
• 3. diarthroses-freely moveable

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• B. Fribrous joints- These are immobile or
  minutely mobile. Examples are the joints of the
  cranium and the teeth. They are lined with
  fibrous tissues (dense regular tissue).
• 1. Sutures- immoveable joints formed by skull
  bones and connected by fibrous tissue.

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• 2. Syndesmosis- slightly moveable but no true
  movement, formed by a ligament band of fibrous
  tissue

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• 3. Gomphoses-peg in socket as in the tooth and
  gum containing a small ligament

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• C. Cartilaginous joints-articulating bones are
  united by cartilage, no joint cavity, not highly
  moveable.
• 1. Synchondroses- hyaline cartilage that unites
  bones as in the ribs and sternum

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• 2. Symphyses- fibrocartilage that unites bones as
  in the pubic symphysis and intervertebral bones.

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• D. Synovial joints-most moveable, has fluid
  filled cavity with synovial fluid, called
  diarthrosis.
• 1.Basic Features-hyaline cartilage lines the
  ends of bones, a cavity filled with fluid
  called synovial fluid is contained by a fibrous
  capsule. It that has an outer layer of dense
  irregular tissue and joins the periosteum and
  an inner layer of synovial membrane (makes
  synovial fluid). The synovial fluid is viscous
  liquid that lubricates the joint. Ligaments
  reinforce the joint and nerves protect it from
  over stretching. Some joints also have a
  meniscus (articular discs) such as the knee
  joint.

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Typical Synovial Joint
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Synovial Joint with articulate disc (meniscus)
in the middle
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• 2. Function (mobility)- these joints are highly
  lubricated to facilitate motion, they routinely
  experience compression and the fluid moves to
  accommodate the pressure.
• 3. Joint stability- some joints have
  articulating surfaces that stabilize the joints
  such as the elbow and hip joint. Ligaments
  strengthen the joint and prevent it from moving
  incorrectly, they are not as flexiable and
  capable of reshaping.
• 4. Joint classification- the following
  classifications are based on joint shape.
• a. plane joints- flat articulating surfaces that
  allow for short gliding movements as in the wrist
  bones (intercarpals), ankle bones (intertarsals),
  and vertebral bones, no rotation around an axis
  (non-axial).

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• b. hinge joints- movement is along one plane
  (uniaxial) such a hinged door. Examples are the
  elbow and knee.

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• c. pivot joints- rounded end of one bone fits
  into the other, also uniaxial, examples are the
  radius and ulna and atlas and dens.

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• d. condyloid joints-(knuckle like) oval like
  shape of one bone fits into an oval bowl like
  shape of the other. It does not rotate around its
  axis but can move sided to side and back and
  forth, it is biaxial.

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• e. saddle joints- the two ends fit into one
  another as a person sitting in a saddle does.
  They are biaxial such as the thumb joint (first
  carpometacarpal joint)

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• f. ball and socket joints- spherical end fits
  into round socket, allows movement in multiple
  planes of axis (triaxial) such as the hip and
  shoulder.

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• 5. Selected synovial joint
• a. temporomandibular joint- this is a synovial
  joint that has an articular capsule, hinge like
  movement, and anterior movement. Because it is so
  shallow it can be easily dislocated.

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Lateral Movement of TMJ
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• b. shoulder joint- less stable but more
  moveable, the glenoid fossa is lined with
  fibrocartilage called the genoid labrum,
  ligaments support limb weight and muscle tendons
  contribute to stability. This joint has a rotator
  cuff formed by tendons. It also has bursa and
  tendon sheaths.

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• c. elbow joint- stable hinge joint, ligaments
  stabilize and prevent lateral/medial movements.

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Lateral View
Medial View
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• d. hip joint- stable ball-and-socket joint, wide
  range of motion but less than shoulder joint due
  to more depth. Also has a rim of fibrocartilage
  called acetabular labrum that prevents the femur
  from slipping. Capsular ligaments provide
  stability.

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Anterior View Posterior View
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Knee Joint Information

• e. knee joint- largest and most complex, it
  includes the femur, tibia, and patella. It
  contains
• 1) several bursae,
• 2) lateral and medial menisci (fibrocartilage
  rings) that guide the condyles.
• 3) three anterior ligaments originating from
  patella to tibia patellar ligament, medial and
  lateral ligament
• 4) fibular and tibial collateral ligaments
  support the joint capsule
• 5) anterior and posterior cruciate- attaches
  across joint internally
• 6) ligaments from fibula to femur anterior or
  posterior

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• Anterior view of the knee.
• A lateral blow can cause the femur and tibia to
  separate tearing several ligaments that are
  attached to each other.
• Pg. 234

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• E. Joint disorders
• 1. Sprain-stretch or torn ligaments
• 2. Dislocation (luxation)- bones are forced out
  of alignment and must be reduced (returned to
  original location). Subluxation is a partial
  dislocation.
• 3. Torn cartilage- when it is subjected to high
  compression and tension, example meniscus
  tearing. It does not heal itself thus broken
  fragments are removed by arthroscopic surgery.
• 4. bursitis/tendonitis- swelling of the bursa or
  tendon sheaths
• 5. arthritis- inflammation or degeneration of
  the joints.
• a. osteoarthiritis- related to aging, the
  joints wear out. Use of joint causes enzyme
  that breakdown the cartilage to breakdown,
  occurs more often in misaligned joints may form
  bone spurs. It happens often in non-synovial
  joints.

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Deformity caused by rheumatoid arthritis
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• b. rheumatoid arthiritis- it is an autoimmune
  disease in which the immune system attacks the
  cartilage causing inflammation and muscle
  weakness. It affect women more than man and
  joints bilaterally and simultaneously.
• c. gouty arthiritis- uric acid accumulates in
  joints causing inflammation at the joints. It
  affects men more than women and if untreated can
  lead to fused bones.
• d. Lyme disease-bacteria transmitted by tick
  bites causes joint inflammation and many other
  symptoms. It is difficult to diagnose and treat.
• F. Joints throughout life
• Synovial joints originate from mesenchyme,
  joints are modified after use by movement and
  use- more active joints are more massive.
  Epiphyseal plates are vulnerable during youth.
  With aging the joint become arthritic although
  this can be delayed with exercise.
• Good luck preparing for the test!!!!!

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• Movement of synovial joints-
• Angular movements- increase or decrease the joint
  angle and bring limb towards or away
• 1. Flexion- reduces joint angle (bending at the
  joint) brings bones closer, usually in the
  sagittal plane
• 2. Extension- increases joint angle
  (straightening joint) brings bones further apart
• 3. Hyperextension- increasing joint angle beyond
  its normal range
• 4. Abduction- moving the joint such that limbs
  are moved away from the body
• 5. Adduction- moving the joint such that limbs
  are moved toward the body
• 6. Circumduction- a combination of flexion,
  extension, abduction, and adduction. (making a
  circle)
• 7. Rotation-movement of bone along its own long
  axis only three areas can do this atlas and
  axis, shoulder joint, hip joint. Medial
  rotation- movement towards the median . Lateral
  rotation- movement away from the median
• 8. Supination- lateral radial rotation to turn
  palm anteriorly
• 9. Pronation-medial radial rotation to turn palm
  posteriorly
• 10. Dorsiflexion-lifting foot to superior side of
  foot approaches shin
• 11. Plantar flexion-depressing the foot (pointing
  toes)
• 12. Inversion-turn sole of foot medially
• 13. Eversion-turn sole of foot laterally
• 14. Protraction and Retraction- non angular
  movement, forward protaction backretraction
• 15. Elevation- moving body part superiorly
• 16. Depression- moving body part inferiorly

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1. Flexion- reduces joint angle (bending at the
joint) brings bones closer, usually in the
sagittal plane 2. Extension- increases joint
angle (straightening joint) brings bones further
apart 3. Hyperextension- increasing joint angle
beyond its normal range
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1. Flexion- reduces joint angle (bending at the
joint) brings bones closer, usually in the
sagittal plane 2. Extension- increases joint
angle (straightening joint) brings bones further
apart 3. Hyperextension- increasing joint angle
beyond its normal range
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1. Flexion- reduces joint angle (bending at the
joint) brings bones closer, usually in the
sagittal plane 2. Extension- increases joint
angle (straightening joint) brings bones further
apart 3. Hyperextension- increasing joint angle
beyond its normal range
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4. Abduction- moving the joint such that limbs
are moved away from the body 5. Adduction- moving
the joint such that limbs are moved toward the
body 6. Circumduction- a combination of flexion,
extension, abduction, and adduction. (making a
circle) 7. Rotation-movement of bone along its
own long axis only three areas can do this atlas
and axis, shoulder joint, hip joint. Medial
rotation- movement towards the median . Lateral
rotation- movement away from the median
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8. Supination- lateral radial rotation to turn
palm anteriorly 9. Pronation-medial radial
rotation to turn palm posteriorly 10.
Dorsiflexion-lifting foot to superior side of
foot approaches shin 11. Plantar
flexion-depressing the foot (pointing toes)
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12. Inversion-turn sole of foot medially 13.
Eversion-turn sole of foot laterally 14.
Protraction and Retraction- non angular movement,
forward protaction backretraction
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15. Elevation- moving body part superiorly 16.
Depression- moving body part inferiorly