Joints

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Joints
Chapter 14
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Joints

• aka articulations
• Point at which two bones join together
• Allow movement
• Transmit forces
• Anatomy
• Capsule or ligaments
• Synovial membrane
• Articular cartilage
• Joint space filled with
  synovial fluid

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Classifications

• Structural Categories
• Fibrous
• Cartilaginous
• Synovial
• Functional Categories
• Synarthrosesimmoveable
• Amphiarthrosesslightly moveable
• Diarthrosesfreely moveable

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Synarthroses

• Immoveable joints
• Lack synovial cavity
• Held together by fibrous connective tissue
• Structural types
• Sutures
• Syndesmoses
• Gomphoses

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Synarthroses

• Sutures
• Thin layer of dense fibrous connective tissue
• Unites bones of skull
• Syndesmosis
• Joints where bones connected by ligaments
• i.e. fibula/tibia and radius/ulna
• Gomphosis
• Conical process fits into socket and is held in
  place by ligaments
• i.e. tooth in alveolus (socket), held in place by
  peridontal ligament

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Amphiarthroses

• Slightly moveable
• Connected by hyaline cartilage or fibrocartilage
• i.e. ribs to sternum or vertebrae

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Diarthroses

• aka synovial joints
• Freely moveable
• Ends of opposing bones are covered with articular
  cartilage
• Separated by joint cavity
• Components of joints enclosed in dense fibrous
  joint capsule

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Synovial joint
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Synovial Joint Anatomy

• Articular capsule
• Aka Joint capsule
• Consists of bundles of collagen and functions to
  maintain a relative joint position

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Synovial Joint Anatomy

• Ligaments
• Bundles of collagen fibers forming a connection
  between bones

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Synovial Joint Anatomy

• Intrinsic ligaments found where the articular
  capsule has become thickened in places
• Shoulder, Hip
• Extrinsic ligaments separate from the capsular
  thickening
• ACL

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Synovial Joint Anatomy

• Ligaments are strongest in the middle and weakest
  at the ends
• Constant compression and tension will cause
  ligaments to deteriorate
• Intermittent compression and tension will
  increase strength and growth

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Synovial Joint Anatomy

• Synovial Membrane and Synovial Fluid
• Lines the synovial joint(articular) capsule
• Made of connective tissue with flattened cells
• Synovial fluid acts as a lubricant.
• Able to vary its viscosity (thicker with slower
  movements and it thins with faster movements)

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Synovial Joint Anatomy

• Articular Cartilage
• Hyaline cartilage Found on the articular ends of
  our long bones
• Fibrocartilage cushioning type of cartilage
• Found in the menisci in our knees, intervertebral
  disks, pubic symphysis
• Elastic cartilage found in the external ear and
  eustachian tube

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Synovial Joint Anatomy

• Bursa
• Fluid-filled sac of synovial tissue found in our
  synovial joints.
• Found in between anatomical structures to reduce
  friction
• Can become chronically inflammed

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Synovial Joint Stabilization

• Muscle tension is important in limiting unwanted
  joint movement
• If joint capsule is overstretched, reflex
  contraction of muscles in the area prevent
  overstretching (Hiltons Law)

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Synovial Joint Stabilization

• Joints that are shallow and fit poorly must
  depend on capsular structures or muscles for
  support

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Synovial Joint Stabilization

• Capsular and ligamentous tissue help to maintain
  anatomical integrity and structural alignment of
  synovial joints

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Synovial Joints

• 6 Types Synovial Joints
• Pivot joint
• Gliding joint
• Hinge joint
• Condyloid joint
• Ball-and-Socket joint
• Saddle joint

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Pivot Joint

• Radius, ulna

• Freely moveable joint in which bone moves around
  central axis, creating rotational movement

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Gliding Joint

• Allows bones to make sliding motion
• Carpals and tarsals
• Between vertebrae
• and spine

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Hinge Joint

• Allows only flexion and extension
• Convex surface of one bone fits concave surface
  of other
• Knee, elbow, phalanges

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Condyloid Joint

• aka ellipsoidal joint
• Bones can move about one another in many
  directions, but cannot rotate
• Named for condyle-containing bone
• Metacarpals, phalanges

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Ball Socket Joint

• One bone has rounded end that fits into concave
  cavity on another bone
• Widest range of movement possible
• Hips, shoulders

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Saddle Joint

• Two bones have both concave and convex regions,
  shape of two bones complementing one another
• Wide range of movement
• Thumb only saddle joint in body

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Movements of Diarthroses

• Flexion
• Extension
• Hyperextension
• Abduction
• Adduction
• Rotation
• Circumduction
• Elevation
• Depression

• Supination
• Pronation
• Plantar flexion
• Dorsiflexion
• Inversion
• Eversion
• Protraction
• Retraction
• Opposition

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Flexion/Extension
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Abduction/Adduction

• Abductionmoving a body part away from midline
• Adductionmoving a body part toward the midline

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Abduction/Adduction
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Internal/External Rotation

• Internal rotationrotation towards the center of
  the body
• aka medial rotation
• External rotationrotation away the center of the
  body
• aka lateral rotation

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Internal/External Rotation
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Hip Internal Rotation
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Foot Dorsal/Plantar
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Plantar Flexion/Dorsiflexion
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Supination/Pronation
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Elevation/Depression
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Inversion/Eversion
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Joints of Upper Extremity

• Shoulder Joint
• Glenohumeral
• Sternoclavicular
• Acromioclavicular
• Elbow Joint
• Radiohumeral
• Humeroulnar
• Radioulnar

• Wrist
• Radiocarpal
• Intercarpal
• Carpalmetacarpal
• Hand
• Intermetacarpal
• Metacarpalphalangeal
• Interphalangeal

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Shoulder

• Glenohumeral
• Sternoclavicular
• Acromioclavicular

Glenohumeral joint
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shoulder
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Elbow

• Radiohumeral
• Humeroulnar
• Radioulnar

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Wrist

• Radiocarpal
• Intercarpal
• Carpalmetacarpal

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Hand

• Intermetacarpal
• Metacarpalphalangeal
• Interphalangeal

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Joints of Lower Extremity

• Sacroiliac
• Acetabulofemoral
• Patellofemoral
• Tibiofemoral
• Tibiofibular

• Ankle/Foot
• Talocural
• Subtalar
• Intertarsal
• Tarsometatarsal
• Intermetatarsal
• Metatasophalangel
• Interphalangeal

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Sacroiliac joint
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• TIBIOFIBULAR JOINT

• Tibiofemoral joint

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Foot/Ankle
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Synovial Joint Injuries

• Acute
• Sprains
• Synovitis
• Subluxations
• Dislocations

• Chronic
• Osteochondrosis
• Arthritis
• Bursitis
• Capsulitis/synovitis

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Sprains

• General Symptoms
• Joint swelling
• Local temperature increase
• Pain
• Point tenderness
• Skin discoloration

• Injury to ligamentous and capsular tissue
• Traumatic joint twist that results in stretching
  of total tearing of the stabilizing connective
  tissue
• One of most common disabling sports injuries

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Sprains

• Grade 3
• Severe sprain
• Extremely painful initially
• LOF
• Severe instability
• Tenderness
• Swelling
• May represent subluxation that reduced
  spontaneously

• Grade 1
• Some pain
• Minimum LOF
• Mild point tenderness
• Little or not swelling
• No abnormal motion
• Grade 2
• Pain
• Moderate LOF
• Swelling
• Slight to moderate instability

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Synovitis

• Irritation of synovial membrane
• Causes increase in fluid production, swelling
• Joint pain during motion, skin sensitivity from
  pressure
• Diminish in few days

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Acute Joint Injuries

• Subluxation
• Occurs when bone displaces, then returns to
  normal position

• Dislocation
• Occurs when significant force displaces bone so
  that the two bone ends in a joint no longer add up

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Osteochondrosis

• Degenerative changes in the ossification centers
  of the epiphysis of bones
• During periods of rapid growth in children
• Osteochondritis dissecans
• Suggested causes
• aseptic necrosis circulation to epiphysis
  disrupted
• Trauma causes particles of articular cartilage to
  fx, resulting in fissures that penetrate to
  subchondral bone

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Arthritis

• Inflammation of an entire joint
• Usually involves all tissues of the joint
• Most often in WB joints
• 100 varieties of arthritis
• 10 population
• No cure

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Rheumatoid Arthritis

• Connective tissue disorder resulting in severe
  inflammation of small joints
• Cause unknown
• Severely debilitating
• Synovial membranes of joint and connective
  tissues grow abnormally to form layer in joint
  capsules? destroys cartilage and fuses bones of
  joint

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Osteoarthritis
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Osteoarthritis
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Bursitis

• Inflammation of the synovial cavity caused by
  excessive stress or tension

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Open Closed Kinematic Chains

• Open Kinematic Chain
• Sequence of action in which the body part
  farthest from the trunk is free during movement
• i.e. Seated leg extension
• Closed Kinematic Chain
• Sequence of action in which the body part
  farthest from the trunk is fixed during movement
• i.e. In a squat, feet are fixed and the rest of
  leg chain moves

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