2.2 Articulations Flashcards
Joints (articulations)
-point of contact between: *bones
*bones and cartilage
*bones and teeth
-can involve bony surface+ tendons + ligaments + cartilage + muscles + accessory structures
Joints (articulations) major functions
- skeletal mobility
- structural support
- protection
*greater mobility = less stability - lesser mobility = greater stability
classification of joints
- based on function:
*synarthrosis (immovable)
*amphiarthrosis (slightly movable)
*diarthrosis (freely movable) - based on structure:
*fibrous
*cartilaginous
*synovial
functional classification
- Synarthroses: immovable joints
ex: cranial sutures - Amphiarthroses: slightly movable joints
ex: pubic symphysis - Diarthroses: freely movable joints
ex: most appendicular joints
fibrous
(immovable)
- joined by fibrous tissue (dense fibrous connective tissue)
- no joint cavity present
cartilaginous
(immovable or slight movable)
- joined by cartilage tissue
- no joint cavity present
synovial
(freely movable)
- most common type
- bones separated by fluid-filled joint cavity
syndesmosis
fibrous joint
- connection via ligaments
- little movement
ex: tibia/fibula
suture
fibrous joint
- seam of connective tissue that interlocks bone
- immovable
ex: cranial structure
gomphosis
fibrous joint
- peg-in socket joint
- immovable
ex: tooth & jaw
synchondrosis
cartilaginous joints
- hyaline cartilage connects bone
- immovable joints
symphysis
cartilaginous joints
- fibrocartilage connects bone
- shock absorption + limited range of motion
synovial joints
- bone separated by fluid-filled joint capsule
- freely movable joint
- most joints of the body
articular cartilage
synovial joints
- layer hyaline cartilage
- reduce shock, friction
joint cavity
synovial joints
- filled with accessory structures and small amount of synovial fluid
joint capsule
- fibrous capsule - dense irregular connective tissue that is continuous with the periosteum
- synovial membrane - loose connective tissue
*covers everything not covered by articular cartilage
*makes synovial fluid
synovial fluid
- fills open space within the joint (typically <3 mL)
- lubricates articular cartilages to reduce friction, absorbs shock, carries nutrients via diffusion to chondrocytes
- largely made of hyaluronic acid and lubricin (polysaccharide)
reinforcing ligaments
- support, strength, reinforce
- can be inside (intracapsular) or outside (extracapsular) the joint capsule
- most common = thickened portion of fibrous layer of articular capsule
nerves and blood vessels
- sense movement at joints
- rich blood vessel supply to synovial membrane
fat pads
synovial joints - accessory structure:
- packing material at periphery, fill space as bone move
articular discs
synovial joints - accessory structure:
- pads of fibrous cartilage
- AKA meniscus
tendons
synovial joints - accessory structure:
- pass through or around joint
bursae
synovial joints - accessory structure:
- bags of synovial fluid
- reduce friction and absorb shock
- common where tendons, ligaments, muscles, skin, or bones typically rub
articular surface
synovial joints - stabilizing factors
- shapes dictates possible movement at joint
ex: hip vs. shoulder joints
ligaments
synovial joints - stabilizing factors
- capsules & ligaments restrict range of motion
- more ligaments –> stronger joint
- work with other structures for stability
muscle tone
- constant, low level of skeletal muscle contraction –> taught tendons –> more stable joint
- stronger muscles around joint –> greater tone –> greater stability
synovial joint type
- ball & socket
- pivot
- hinge
- plane
- condylar
- saddle
articulation example
- direct relationship between structure and function
ex: shoulder, hip, knee
synovial joints - shoulder
- ball & socket joints
ball = head of the humerus
socket = glenoid cavity of the scapula - greatest range of motion of any joint in the body
ex: *bones (humerus & scapula)
*ligaments (coracohumeral)
*cartilage ( glenoid labrum)
*muscle + tendons (rotator cuff)
*bursae (subdeltoid)
synovial joints - hip
- ball & socket joint:
ball = head of femur
socket = acetabulum of the os coxae - deeper socket = lesser range of motion than the shoulder = greater stability
ex: *bone (femur & os coxae)
*ligaments (iliofemoral)
*cartilage (labrum)
*bursae (greater trochanteric)
*muscles (gluteal group)
subluxation
- partial dislocation of the joint
—> little tissue damage - head of femur comes completely away from acetabulum->dislocation
synovial joints - knee
- supports body weight (and greater)
- hinge joint + slight rotation when flexed:
*tibia + femur
*fibula + femur
ex: *bone (femur, fibula, tibia)
*cartilage (lateral meniscus)
*bursae
*fat pads
*ligaments - muscles (quadriceps & hamstrings groups)
cartilage tears
break in continually of cartilage
ex: meniscus
sprains
stretching or tearing of tendons/ligaments
ex: ankle
dislocations
bones at joint are forced out of alignment
ex: shoulder
bursitis/tendonitis
inflammatory/ degenerative diseases that affect joints
arthritis
collection of inflammatory / degenerative diseases that affect joints
