Week 2 - Joints Flashcards
Name all the types of joints
- synovial joints
- syndesmosis
- synchondrosis
- synostosis
- symphysis
- gomphosis
What is a synovial joint and where is it found?
Joint with two opposing surfaces covered by cartilage, bathed in synovial fluid within a joint capsule
- found in most appendicular joints
- posterior joints of spine
What is a syndesmosis and where is it found?
Joint where two bones are joined by fibrous tissue only.
- found in skull sutures
- found between distal end of tibia and fibula
What is a synchondrosis and where is it found?
Two bones are joined by cartilage.
- found in physis (joins epiphysis & metaphysis)
What is a synostosis and where is it found?
Bones are fused together obliterating joint.
- found in bones of the pelvis
What is a symphysis and where is it found?
Two bones joined by cartilage but with no synovial fluid (and therefore very little movement).
- found at symphysis pubis
- found between vertebrae
What is a gomphosis and where is it found?
Fibrous connection between a tooth and its socket. Blood vessels and nerves cross the joint
When do synovial joints begin to develop?
At 6-9 weeks in development.
Which develops first: upper or lower extremity?
upper extremity
What are the 4 stages of joint development?
- Homogenous Interzone
- Three-layer interzone
- Early liquefaction of middle layer
- Full separation and joint cavitation
What is found in the homogenous interzone of developing bone?
Mesenchymal cells
What will the mesenchymal interzone develop into?
- articular cartilage
- meniscus
- cruciate ligaments
- collateral ligaments
(these happen before development of synovial fluid
What is found in the three-layered interzone?
- two layers of densely packed cells (become articular surfaces).
- one layer of loosely packed undifferentiated cells in between the dense layers.
What is the tiny sesamoid bone located BEHIND the knee called?
flabella
What are the layers of the synovium?
- briefly decribe each
Outer: rich supply of blood vessels, nerves, and lymph
Inner: thin syncytium
What cells are found in the inner layer of the synovial membrane?
Type A –> cells specialized to clear waste material
Type B –> cells specialized to synthesize hyaluronic acid
What is synovial fluid composed of?
dialyzed plasma with glycoprotein and hyaluronic acid
Approximately how much synovial fluid would you find in the knee?
~5 cubic cm
What is the joint capsule?
tough fibrous tissue that joins the two bones of a joint
What is a bone bruise?
Injury to the subchondral bone
Name a couple examples of tendons that are intra articular.
Biceps; popliteus
What happens when a joint is injured?
- injury (twist/fall/etc)
- inflammation (redness, swelling, pain, heat)
- effusion (increase in joint fluid volume)
- healing/resolution
What is immediate joint swelling after an injury indicative of?
hemarthrosis
- -> fracture
- -> significant ligament/capsular injury
What is development of a bruise indicative of?
bleeding into subdermal tissue
What is the healing response for a synovial joint injury?
substitution of collagen into hemorrhagic tissue
What are the two main mechanisms for injury to joint cartilage?
Abnormal force on normal joint (seen more often in younger patients involved in high-intensity sports)
Normal force on abnormal joint (seen more often in older patients)
How does articular cartilage heal?
Doesn’t heal except in very young patients.
Instead will get replaced with fibrocartilage (Type I collagen) but this is not as durable
Why does blood not clot within the knee capsule?
The synovial fluid mixes with the blood and has factors that prevent clotting
How do extraarticular ligaments heal?
With a fibrin clot
- fibroblasts proliferate & secrete matrix
- forms early tissue type III collagen
- remodels to resemble normal ligament (Type I collagen)
- contraction of healing tissue
What are the extra articular ligaments of the knee?
MCL & LCL
What are the effects of decreased loading on a joint?
Loss of PGs
Muscle, tendon, & bone become deconditioned
What are the components of a synovial joint?
- bone
- Articular cartilage
- two opposing bones
- fibrous capsule & ligaments
- synovial membrane
- synovial fluid
- supportive fibrocartilage (tissue inside a specific joint for stability)
- tendons
- associated nerves and vessels
What are the categories of intrinsic causes of joint pain?
Articular & Non-articular
What are the categoris of extrinsic causes of joint pain?
Generalized, Neurologic, & Referred pain
What are some examples of articular causes of joint pain?
- arthritis
- neoplasm
- trauma
What are some examples of non-articular causes of intrinsic joint pain?
- bursitis
- tendonitis
- myositis
What are some examples of neurologic causes of joint pain?
- nerve root compression
- HCV
What are some examples of generalized causes of joint pain?
- fibromyalgia
- dermatomyositis
