Chapter #8: Joints Flashcards
(83 cards)
1
Q
Joints
A
(articulations) the site where two bones meet (may or may not allow movement)
2
Q
What are the general functions of joints?
A
Mobility & Stability
3
Q
Mobility
A
Allow movement of various body parts
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Q
Stability
A
hold the skeleton together (holds bones in place and prevent damage to internal structures)
5
Q
Which skeleton has more mobility?
A
Appendicular skeleton
6
Q
Which skeleton has more stability?
A
Axial skeleton
7
Q
Structural Classifications of Joints
A
Fibrous, cartilaginous, and synovial
8
Q
Fibrous joints
A
joints composed of collagen fibers of connective tissue (no joint cavity present; movement allowed with mostly synarthroses and a few amphiarthroses)
9
Q
Types of fibrous joints
A
sutures, syndesmoses, and gomphoses
10
Q
Sutures
A
Found only between bones of the skull (composed of bundles of very short & strong collagen fibers) and permits very little movement
11
Q
Why do you want little movement with sutures?
A
don’t want anything injuring your brain
12
Q
What happens to sutures over time?
A
ossifies over time in adults to form syntoses
13
Q
Syndesmoses
A
bones are connected to each other only by ligaments (movement allowed by joint depends on the length of the ligament bands)
14
Q
Ligaments
A
bands of fibrous tissue that join bone to bone
15
Q
What is the relationship between length and movement allowed within ligaments?
A
more length = more movement
16
Q
Gomphoses
A
only joint type that does not join bone to another bone (joins tooth to bony alveolar socket)
-fibers of joint are very short, providing very limited movement (exception: braces)
17
Q
Periodontal Ligament
A
joins the bone of the mandible/maxilla to the tooth
18
Q
Cartilaginous Joints
A
bones joined by cartilage
-no joint cavity
-movement allowed: synathroses & amphiarthroses
19
Q
Types of cartilaginous joints
A
Synchondroses & symphyses
20
Q
Synchondroses
A
bones unites with a plate of hyaline cartilage
-mostly synathroses
-ex. epiphyseal plate in long bones, costal cartilage
21
Q
Symphyses
A
fibrocartilage joins bone
-some movement allowed, but limited (see this with joints that bear a lot of weight)
-ex. intervertebral joints (discs can herniate)
-ex. pubic symphysis
22
Q
What is the benefit of fibrocartilage at symphyses joints?
A
Permitting small amount of movement prevents injury
23
Q
Synovial joints
A
possesses joint cavity, diarthroses, most joints fall under this category
24
Q
Why are almost all synovial joints found in the appendicular skeleton?
A
we need lots of movement
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Structures found in synovial joints
articular cartilage, joint cavity, articular capsule, synovial fluid, reinforcing ligaments, innervation & vascularization
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Articular Cartilage
hyaline cartilage covering bone ends
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What is the function of articular cartilage?
prevents bone from rubbing on bone
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Joint cavity
small space between articulating bones
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What is the function of a joint cavity?
responsible for temporarily storing synovial fluid
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Articular capsule
two-layered capsule that encloses the joint cavity
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What two layers make up the articular capsule?
Fibrous layer and synovial membrane
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Fibrous layer
outer layer that is continuous with periosteum of bones
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What is the function of the fibrous layer?
connects one bone to the bone it joins with; reinforces structure
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Synovial membrane
inner layer that lines joint cavity
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Where is the synovial membrane NOT found?
never found where articular cartilage is found; never found wrapped around bone ends
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What is the function of the synovial membrane?
produce and secrete synovial fluid
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Synovial fluid
slippery fluid occupying space in joint capsule & articular cartilages
-when the joint is not active, fluid is viscous
-when the joint is active, fluid thins, becomes watery
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What is the function of synovial fluid?
allow joints to slide past one another; prevents articular cartilage from breaking down
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Where is the synovial fluid found when the joint is not active?
fluid will soak up into articular cartilage and become thicker
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Where is the synovial fluid found when the joint is active?
in the joint cavity
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Reinforcing ligaments
bandlike ligaments that join articulating bones (reinforce articular capsule; extend from one bone to joining bone)
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What is the function of reinforcing ligaments?
reinforce joint to prevent bones from coming out of place & excessive movement; may limit mobility to an extent
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Innervation & Vascularization
Innervation to synovial joints: joints supplied with sensory nerve fibers
Vascularization: rich blood supply to joints, nutrients to synovial fluid
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What sensation(s) do we typically perceive at joints?
Stretch, pain, and position
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Why is innervation to the joints important?
-sensing overstretch which can lead to injury
-position: you can feel if bones are not lined up properly
-if you ignore stretch and position, you feel pain
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Structures that may (or may not) be associated with synovial joints (depends on the joint)
Bursae & tendon sheath
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Bursae
flattened sacs that contain a small amount of synovial fluid
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Where are you most likely to find bursae?
in between structures that would otherwise rub together
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What is the function of bursae?
reduce friction between adjacent structures
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Tendon sheath
elongated bursa that wraps completely around a tendon subjected to frequent friction
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Where in the body do you typically see tendon sheaths?
found where tendons are packed closely together; avoid rubbing tendons
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What is the function of tendon sheaths?
prevents excessive friction for a particular tendon
ex. wrists & ankles have tendon sheaths and if there are not enough tendon sheaths, then tendonitis can occur
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Factors influencing joint stability
articular surfaces, ligaments, muscle tone
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Articular surfaces
how well do the two articulating bones fit together
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Ligaments
the more ligaments, the stronger the joint; reinforcing ligaments however must be joined by other factors
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Muscle tone
tendons attach muscle to bone & often wrap around/over joints; this braces the joint and holds it in place; most important because tendons are thicker than ligaments
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What is the relationship between mobility and stability?
more mobility = less stability
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Types of movements allowed by synovial joints
Nonaxial movement, uniaxial movement, biaxial movement, and multiaxial movement
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Nonaxial Movement
-No axis around which movement takes place
-bones that articulate have flat surfaces
-movement allowed: gliding
-Joint shape: plane joint
-ex. intercarpal & intertarsal joints
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Uniaxial Movement
-Allows for movement of joint around a single axis
-Movement allowed: flexion, extension, rotation
-joint shape: hinge joint (ex. between humerus & ulna)
-joint shape: pivot joint (ex. between radius & ulna)
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Biaxial Movement
-Allows for movement of a joint around two axes
-Movement allowed: flexion/extension AND adduction/ abduction
-joint shape: condylar joint (ex. knuckle of finger)
-joint shape: saddle joint (ex. joint at base of thumb)
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Multiaxial Movement
-Allows for movement of a joint around multiple axes
-Movement allowed: flexion/extension, abduction/adduction, AND rotation
-joint shape: ball-and-socket joints (ex. should & hip joints)
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Specific Examples of Synovial Joints
TMJ, Glenohumeral joint, elbow joint, coxal joint, knee joint
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Temporomandibular Joint (TMJ)
-where the mandible articulates to the temporal bone
-Joint shape: modified hinge joint
-Articular disc divides synovial cavity into superior and inferior portions
-Superior: allows lateral excursion
-Inferior: allows elevation/depression
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Glenohumeral (shoulder) Joint
-where the humerus articulates with the scapula
-Most freely moving joint in the body, but still needs some stability:
1) Reinforcing ligaments are very thin and loose
-Coracohumeral ligament & glenohumeral ligaments
2) Rotator cuff
-4 muscles (and their tendons) encircle the joint
3) Glenoid labrum
-Rim of fibrocartilage around glenoid fossa; provides some stability
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How does the glenoid labrum provide stability?
serves to slightly deepen sockets
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Elbow Joint
-where the humerus articulates with the ulna
- Stability provided by:
1) Close fit of trochlea (on humerus) and trochlear notch (on ulna)
2) Muscle and tendon of arm muscles wrap around elbow to provide further stability
3) Ulnar collateral ligament (medial side) and radial collateral ligament (lateral side) prevent lateral movement
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Coxal Joint
-where the head of the femur articulates with the os coxa
-Stability provided by articular surfaces and strong ligaments
-Acetabulum of os coxa has acetabular labrum to further deepen socket
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Ligaments of the articular capsule
Iliofemoral ligament, pubofemoral igament, ischiofemoral ligament
-twist and wrap around joints; help brace for standing & walking
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Ligamentum teres
ligament of the head of the femur
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Knee Joint
single joint cavity shared by 3 separate joints
1) Femoropatellar joint (1): between patella and femur
2) Tibiofemoral joint (2) : between femur and tibia (1 medial, 1 lateral)
-Muscle and tendon reinforces joint with several ligaments
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Important Stabilizing Structures in the Knee Joint
Menisci, Extracapsular & capsular ligaments, Intracapsular ligaments
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Menisci
thin layer of fibrous cartilage at outer margins of tibiofemoral joints
-Forms ridges along outer margins of joint
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Extracapsular & capsular ligaments
prevent hyperextension of knee
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Intracapsular ligaments
(cruciate ligaments) secure articulating bones, prevent displacement
-Anterior crulate ligament (ACL)
-Posterior crulate ligament (PCL)
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Anterior crulate ligament (ACL)
prevents forward sliding of tibia & prevents hyperextension of knee
-Attaches to anterior portion of tibia
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Posterior crulate ligament (PCL)
prevents backward sliding of tibia and forward sliding of femur
-Attaches to posterior portion of tibia
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Homeostatic Imbalances of joints
Arthritis
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Arthritis
-Can be inflammatory or degenerative
-Most widespread crippling disease in North America
-Can be acute or chronic
-Acute forms: bacterial, inflammatory
-Easily treated with antibiotics
-Chronic forms: inflammatory/degenerative, long-lasting
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Types of arthritis
1)Osteoarthritis (OA)
2)Rheumatoid Arthritis (RA)
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Osteoarthritis (OA)
-Most common form of chronic arthritis (progresses slowly & is irreversible - treatment but no cure)
-affects females more than males
-affects farmers and long term labor careers
-Caused by: more articular cartilage being destroyed than is replaced
-Effect: exposed bone rubs together, forming bone spurs
-Bone ends deform, which restricts movement at joint
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Rheumatoid Arthritis (RA)
-autoimmune chronic inflammatory disorder
-bilateral & degenerative condition (bilateral: if it's on one side, it's on the other)
-Joints of fingers, wrist, ankles, feet most likely to be affected
-Individuals with condition have flare-ups followed by periods of remission
-Pain and swelling felt in joints affected by RA during flare-ups
-During periods of remission; no pain/swelling in joints affected by RA
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Progression of Rheumatoid Arthritis
1) Synovial membrane becomes inflamed
2) Lymphocytes and macrophages flood area to destroy cause of inflammation
-Macrophages also destroy some of synovial membrane
3) Synovial fluid accumulates and a pannus forms
-Pannus is a thickening of synovial membrane
-Pannus breaks down cartilage tissue over time
-Ankylosis can occur due to cartilage destruction
-Bones fuse together where cartilage/joints used to be
