Joints and Dislocations Flashcards
Where is cartilage located?
Where mobility is required at articulations (joints)
What causes movement of bones?
Skeletal muscles contracting
What are the 3 types of joint?
Fibrous, cartilaginous, synovial
What is the compromise that has to be made in joints?
Between mobility and stability
What is the relative stability and mobility of fibrous joints?
Limited mobility and stable
What are two types of fibrous joint?
Syndesmoses and sutures
What do syndesmoses do and what is an example?
Unite bones with a fibrous sheet e.g. interosseous membrane
Which of sutures and syndesmoses are more stable?
Sutures
Where are sutures found?
Between the bones of the skull
What are fontanelles?
Wide sutures in the neonatal skull (anterior, posterior, lateral)
What do fontanelles allow?
Frontal, parietal, temporal and occipital bones to slide over each other, making the head smaller for birth
What is the mobility/stability compromise in cartilaginous joints?
Fairly limited motility and relatively stable
What are synchondroses?
Primary cartilaginous joints
Where are synchondroses (primary cartilaginous joints) found?
In bones joined by hyaline cartilage e.g. epiphyseal growth plate
What are symphyses?
Secondary cartilaginous joints (fibrocartilage)
What is an example of a secondary cartilaginous joint?
Intervertebral disc
What occurs when a primary cartilaginous bone slips?
Slipped femoral epiphysis
What occurs when a secondary cartilaginous bone slips?
Slipped disc
What can a slipped disc do?
Compress neural structures (spinal cord or spinal nerves)
What is the outer part of an intervertebral disc?
Outer fibrous annulus fibrosus (fibrous ring)
What is the inner part of an intervertebral disc?
Inner soft nucleus propulsus
Where are synovial joints found?
Two or more bones articulating with each other
What secretes synovial fluid?
Deeper synovial membrane layer
What are synovial joints supported by?
Ligaments
What are the 5 types of synovial joint?
Pivot, ball and socket, plane, hinge, biaxial
What does a pivot joint allow and give an example?
> 45 degree shaking of the head rotation- atlanto-axial joint
What does a plane joint allow and give an example?
Minimal movement in one plane- acromioclavicular joint
What does a hinge joint allow and give an example?
Reasonable range of movement in one plane- elbow joint
What does a biaxial joint allow and give an example?
Reasonable range of movement in one plane and less in another- metacarpophalangeal joint
What does a ball and socket joint allow and give an example?
Good ranges of multi axial movement- hip joint
What is the mobility/stability compromise in synovial joints?
Fairly mobile- not so stable
What does subluxation mean?
Reduced area of contact between articular surfaces
What is a dislocation?
Complete loss of contact between articular surfaces
What type of joint is the TMJ?
Synovial
What is the TMJ an articulation between?
Mandibular fossa and articular tubercle of temporal bone and the head of the mandibular condyle
What happens in a dislocation of the TMJ?
The head of the condylar process of the mandible becomes stuck anterior to the temporal bone tubercle
What will a dislocation of the TMJ show physically?
Mouth wide open and cannot be shut
Dislocation of the TMJ can be bilateral or unilateral, how can you tell the difference?
If the chin is remaining in the midline, it is bilateral
Do the joints have good sensory nerve supply or not?
Yes, they do
What are the 4 sensations detected by the sensory receptors of the joint nerves?
pain, touch, temperature and proprioception
What is a big risk of dislocations?
Damage arteries and compromise blood supply distal to the joint
