Transcript Skeletal System 4 - anderson1.k12.sc.us

Skeletal System 4
Honors Anatomy
to be copied
Joints & Homeostasis
• Joints contribute to homeostasis by holding
bones together in ways that allow movement
& flexibility
Joints
• aka: “articulation” or “arthrosis”
• a point of contact between 2 bones, a bone
& cartilage, or between a bone & tooth
Joint Classification
• 1. structural classification
– based on anatomical characteristics
• Fibrous joints
• Cartilagenous joints
• Synovial joints
• 2. functional classification
– based on type of movement they permit
• Synarthrosis
• Amphiarthrosis
• Diarthrosis
Fibrous Joints
• Articulating bones held very closely together
by fibrous CT
• 3 types:
1. Sutures
– skull bones
2. Syndesmoses
– interosseous membrane
3. Gomphoses
– dentoalveolar joint
Gomphoses
Cartilagenous Joints
• allows little or no movement
• bones are tightly connected by either hyaline
cartilage or fibrocartilage
• 2 types:
1. Synchondoses
– hyaline cartilage connects bones
– epiphyseal plate
2. Symphyses
– fibrocartilage connects bone
– pubic symphysis
Symphyses
Synovial Joints
• distinguishing characteristics:
– synovial joint cavity
• filled with synovial fluid
– bones covered by articular cartilage
• reduces friction
Synovial Fluid
• secreted by synovial membrane
• viscous, clear, pale yellow fluid
• forms film over surfaces w/in articular
capsule
• functions:
1. reduce friction
2. absorbing shocks
3. supporting chondrocytes in w/in articular
cartilage
By the way….
• cracking sounds heard as joints move or
popping sounds people make when the
“crack” their knuckles explanation:
– When synovial cavity expands  creates partial
vacuum  suction from that draws CO2 & O2
out of blood vessels in synovial membrane 
form bubbles in synovial fluid  bubbles pop
Sprains
• a forcible wrenching or twisting of a joint
that stretches or tears ligaments but does
not dislocate the bones
• occurs when ligaments are stressed beyond
their capacity
• may have associated damage to surrounding
blood vessels, muscles, tendons, or nerves
Strains
• stretched or partially torn muscle
• often due to muscle contracting suddenly &
powerfully
Bursae
• saclike structures situated to alleviate
friction in some joints
• filled with fluid similar to synovial fluid
• located between:
– skin & bones
– tendons & bones
– muscles & bones
– ligaments & bones
Bursitis
• inflammation of a bursa
• usually caused by irritation from repeated,
excessive exertion of a joint
• or by: trauma, infection (syphilis or TB), RA
• symptoms: pain, swelling, tenderness,
limited movement
Types of Movements
@
Synovial Joints
• 1. Gliding
• relatively flat surfaces move back-and-forth
& side-to-side
Types of Movements
@
Synovial Joints
• 2. flexion/extension/ hyperextension:
• opposite movements
– flexion: decrease in angle between articulating
bones
– extension: increase in angle between articulating
bones
– hyperextension: continuation of extension beyond
the anatomical position
Types of Movements
@
Synovial Joints
• 3. abduction/adduction/ circumduction
– abduction: movement of bone away from midline
– adduction: movement of bone toward midline
– circumduction: movement of distal end of a body
part in a circle
Types of Movements
@
Synovial Joints
• 4. elevation/depression:
• elevation: upward movement of part of body
(closing mouth, shrugging shoulders)
• depression: downward movement of part of
body (opening mouth, returning elevated
shrugged shoulders to anatomical position)
Types of Movements
@
Synovial Joints
• 5. protraction/retraction
• protraction: movement of part of body
anteriorly in transverse plane
• retraction: returning a protracted part of
body to anatomical position
Types of Movements
@
Synovial Joints
• 6. inversion/ eversion
• inversion: movement of soles medially @
intertarsal joints (soles face each other)
• eversion: movement of soles laterally @
intertarsal joints
Types of Movements
@
Synovial Joints
• 7. dorsiflexion/ plantar flexion
• dorsiflexion: bending foot @ ankle in
direction of dorsum (superior surface)
• plantar flexion: bending foot @ ankle in
direction of plantar surface
Types of Movements
@
Synovial Joints
• 8. supination/pronation
• supination: movement of forearm in which
palm is turned anteriorly
• pronation: movement of forearm in which
distal end of radius crosses over distal end
ulna & palm is turned posteriorly
Types of Movements
@
Synovial Joints
• 9. opposition
• movement of thumb in which thumb moves
across palm to touch tips of the fingers on
same hand
Ball - & - Socket Joint
• ball-like surface of one bone fits into a
cuplike depression of another bone
• permits movement around 3 axis + all
directions in between
– flexion
– extension
– abduction
– adduction
– circumduction
– rotation
Homeostatic Imbalances
• Rheumatoid Arthritis (RA)
• autoimmune disease: immune system
attacks joint linings
• characterized by:
– inflammation of joint  swelling, pain, loss of
function
– usually bilateral joints involved but may not be
to same degree
Medical Terminology
• arthralgia: pain in a joint
• subluxation: partial or incomplete
dislocation of a joint