Joint Structure Flashcards
What are the classifications of joints?
- Diarthrosis (synovial/mobile joint)
- Synarthrosis (immobile joint)
- Amphiarthrosis (between)
What are the subclassifications of diarthrosis/synovial joints based on movement?
- Uniaxial
- Biaxial
- Polyaxial
- Plane
What type of joints are the ulnohumeral joint, and proximal and distal radioulnar joints?
Uniaxial diarthoses
What type of joint is the radiocarpal joint?
Biaxial diarthrosis
What type of joints are the shoulder and hip?
Polyaxial diarthsosis
What type of joints are zygapophyseal joints, patellofemoral joint, and carpal/tarsal joints?
Plane (flat joint) diarthrosis
What are five types of synarthroses?
- Symphysis
- Suture
- Synchondrosis
- Syndesmosis
- Synostosis
What type of joints are the pubic symphysis and intervertebral discs?
Symphysis synarthrosis (technically amphiarthrosis)
What is found within symphysis synarthrosis joints?
Fibrocartilage and ligaments
What is found within suture synarthrosis joints?
Interdigitating bones with ligamentous connections
Where can suture synarthrosis joints be found?
Skull
What type of joint are manubriosternal and costochondral joints?
Synchondrosis synarthrosis
What is found within synchondrosis synarthrosis joints?
Structures with cartilage ends, but no synovium
What type of joint are interosseous membranes are tibiofibular and radioulnar joints?
Syndesmosis synarthrosis
What is found within syndesmosis synarthrosis joints?
Fibrous connections between bones without cartilage
What is a normal variant of synostosis synarthrosis?
5th toe synphalangism
What is a pathological fusion of bones classified as synostosis synarthosis?
SI ankylosis in ankylosing spondylitis
What is a unit load?
Compressive force expressed as kg/cm3
What is the unit load threshold for cartilage injury?
20-26kg/cm3
Excessive unit loads lead to…
damage of articular cartilage
What protects the joint cartilage from exceeding unit load?
- M/C adjacent muscles, tendons
- Extra-articular ligaments
- Joint and bone deformation
- Intra-articular structures (ligaments and menisci)
What are the external support structures of the knee?
Tendons: biceps femoris, patellar
Ligaments: medial and lateral collateral ligaments
Muscles: quadriceps
What are the three types of articular cartilage?
- Hyaline cartilage
- Fibrocartilage
- Elastic cartilage
What type of collagen is found in hyaline cartilage?
Type 2 collagen (resists compressive forces)
What type of collagen is found in fibrocartilage?
Type 1 collagen (resists tensile forces)
What type of collagen is found in elastic cartilage?
Type 2 collagen (and elastin)
What is the weakest type of cartilage?
Hyaline cartilage (susceptible to chondral fractures from tensile forces)
What type of cartilage is found in synovial joints and ribs?
Hyaline cartilage
What type of cartilage is found in the following?
- Menisci
- Triangular cartilage (wrist)
- Labrum (shoulder and hip)
Fibrocartilage
What is the strongest type of cartilage?
Fibrocartilage
What type of cartilage is found in the pinna of the ear, nose, Eustachian tube, and epiglottis?
Elastic cartilage
What is the makeup of extracellular matrix of hyaline cartilage?
70-80% water
20-30% type II collagen and proteoglycans
How does hyaline cartilage appear?
Smooth and white, generally no thicker than 6mm
What is the function of hyaline cartilage?
- Shock absorption
- Low coefficient friction
What are the six zones of joint histology?
- Tangential zone
- Transitional zone
- Radial zone
- Tidal zone
- Calcified zone
- Subchondral bone plate
joint histology
What is found in the tangential zone?
Flat chondrocytes, lots of type II collagen, aka skin of cartilage/armor plate
joint histology
What is found in the transitional zone?
Round chondrocytes, lots of matrix