Upload
marjorie-hodge
View
246
Download
3
Tags:
Embed Size (px)
Citation preview
Joints
Articulations
• Articulations (joints) are places where two or more separate bones in the body meet
• Bones will endure extreme friction if they rub against each other, therefore all joints have at least one of these two traits:– Immobile– Padded with other tissues such
as cartilage
Structural Classification of Joints
• Based on material binding bones together and whether or not a joint cavity is present• Three structural classifications:• Fibrous joint• Cartilaginous joint• Synovial joint• The only movable one
Functional Classification of Joints
• Based on amount of movement allowed by the joint• Three functional classifications:• Synarthrosis—immovable • Amphiarthrosis—slightly movable • Diarthrosis—freely movable
Fibrous Joint
• A fibrous joint is always completely immobile (synarthrosis)
• Composed of dense fibrous connective tissue
• Major example are the sutures in the skull Dense
fibrousconnectivetissue
Sutureline
(a) Suture
Joint held together with very short,interconnecting fibers, and bone edges
interlock. Found only in the skull.
Cartilaginous Joint• A cartilaginous joint is composed of hyaline cartilage
attached to both bones and is often a synarthrosis• Sometimes a disc of fibrocartilage sits between the
articular cartilages of the bones– This is called a symphysis– This type of joint is an amphiarthrosis
Fibrocartilaginousintervertebraldisc
Pubic symphysis
Body of vertebra
Hyaline cartilage
(b) Symphyses
Bones united by fibrocartilage
Cartilaginous Wear
• Remember that cartilage is ossified to bone over time– This continues slowly in
adulthood!• Many cartilaginous joints
becomes less flexible over time– This includes the cartilage of
the ribcage and the pubic symphysis
Synovial Joint
• Any joint that is designed to move more than 2 millimeters is a synovial joint– This includes knee, elbow,
shoulder, jaw, etc.• Each end of the bone is
covered in cartilage, the space between the bones is filled with synovial fluid, and the entire joint is covered in the fibrous capsule
Synovial Joint Structure
• The fibrous capsule protects the joint from the outside
• The synovial fluid prevents the cartilage or bone from ever grinding against each other
• Additionally, ligaments hold the bones together– Ligaments are prevented from
wearing down bone or cartilage by fluid-filled membrane sacs called bursae (sing. bursa)
Anatomy of Major Joints
Basic Joint Movements
• Synovial joints have many types of joints and movements– Flexion/Extension– Abduction/Adduction– Circumduction– Rotation
• These will be covered in lab as well– There are many more specialized movements not
covered here
Flexion/Extension• Movement in the sagittal
plane– Decreased angle = flexion– Increased angle =
extension– Beyond straight =
hyperextension• Vertebral joints
(amphiarthroses) may collectively perform flexion/extension as well
Adduction/Abduction
• Movement in the frontal plane– Away from body =
abduction– Adding to body =
adduction
• Available in many appendicular joints
Circumduction and Rotation
• Circumduction is to inscribe a cone (simultaneous use of flexion/extension and adduction/abduction)– What joints can perform
circumduction?• Rotation is to rotate in
place– What joints can perform
rotation?
Joint Inflammation• A joint may become inflamed
with age– Referred to as arthritis– Rheumatoid arthritis is an
immune reaction to the joint– Osteoarthritis is a wearing down
of the cartilage on a joint and the subsequent thickening of the bone due to friction
• If a bursa becomes inflamed it is called bursitis
That’s all folks!
• Have an excellent weekend!• Don’t forget to take the online quiz!• Next week: Electrical activity, then muscles!