Joints and Dislocations Flashcards
What is the skeleton made of?
Bones and cartilage
What is bone made of?
Hard connective tissue
What are the (4) main functions of bones?
Support & Protection
Calcium Metabolism
Red blood cell formation
Attachment (for skeletal muscles)
What defines cartilages and where is it located?
Less rigid than bone
Located where mobility is required at articulation (joints)
What are the three types of joints and their relative stability & mobility?
Fibrous - most stable / least mobile
Cartilaginous - moderate stability / mobility
Synovial - least stable / most mobile
What are the subtypes of Fibrous joints and their features
Syndesmoses - unite bones with fibrous sheet (partially movable)
Sutures - highly stable
What is an example of a Syndesmoses?
Interrousseous membrane between the fibula and tibia
What is an example of a suture?
Coronal suture
What are fontanelles?
Essentially precursors to sutures - found in neonatal skull - allow growing frontal, parietal, temporal and occipital bones to ‘slide’ over each other –> make’s baby’s head smaller for passage through birth canal
What are the types of cartilaginous joints?
Primary and secondary
What distinguishes primary cartilaginous joints?
Synchondroses: Bones joined by hyaline cartilage
What is the function of synchondroses?
Permit growth in length of bone / ossification and fusion
What distinguishes secondary cartilaginous joints?
Symphyses:
- strong
- slightly movable
A slipped disc can compress which neural structures?
Spinal cord or spinal nerves
What are the 8 typical features of synovial joints?
- Two or more bones articulating with each other
- Articular surfaces covered in hyaline cartilage
- Capsule (wraps around joint)
- Joint cavity (contains synovial fluid)
- (Supported by) ligaments
- Associated with skeletal muscle & their tendons
- Associated with bursae
- Often have special features (unique to each joint)
What makes up a capsule in a synovial joint?
Superficial strong fibrous layer + deeper synovial membrane layer (secretes synovial fluid)
What are ligaments?
Fibrous bands from bone to bone
What is the function of ligaments?
Strengthen and improve stability of the joint
In what way is hyaline cartilage involved in osteoarthritis?
Doesn’t grow back very well
What is the function of bursae?
Prevent friction around the joint
What are tendons?
Fibrous bands from muscle to bone
What are the 5 subtypes of synovial joints?
Pivot, Plane, Hinge, Biaxial, Ball & Socket
What is the range of movement of a pivot (synovial) joint?
> 45° of “shaking the head” rotation
E.g. Atlanto-axial joint
What is the ROM of a ball & socket (synovial) joint?
Good ranges of multi-axial movement (e.g. circumduction)
E.g. Hip joint
What is the ROM of a plane (synovial) joint?
Minimal movement in one plane
E.g. Acromioclavicular joint
What is the ROM of a hinge (synovial) joint?
Reasonable movement in one plane
E.g. Elbow joint
What ist the ROM of a biaxial (synovial joint)?
Reasonable ROM in one plane and less in another
E.g. Caropometacarpal joint
What is mobility and stability determined by?
Joint type, i.e. shape & fit
What is hypermobility?
Pathological or physiological increased mobility at joints
What is subluxation?
Reduced area of contact between articular surfaces
What is dislocation?
Complete loss of contact between articular surfaces
What is the Temporomandibular joint?
Each TMJ is the synovial articulation between the mandibular fossa & the articular tubercle of the temporal bone superior and the head of the condylar process of the mandible inferiorly
The articular disc of the TMJ divides the joint into ___?
superior & inferior cavity
Muscles in the TMJ _____ to allow the mouth to open wide
naturally subluxes
What happens in dislocation of the TMJ?
the head of the condylar process of the mandible becomes ‘stuck’ anterior to the articular tubercle of the temporal bone
What is proprioception
Allows brain to sense where something (e.g. joint) is in space
What are periarticular arterial anastomoses?
periarticular = around the joint anatomises = connection between arteries
What is the purpose of anastomoses?
Prevents blood flow restriction to the joint when the muscle flexes - can be dangerously compromised during dislocation
