Arthrology + Bones of the shoulder Flashcards
Joint definition + functions
- where two bones meet
Functions: - allow movt to occur
general structure + relative amount of movt: fibrous joint
Fibrous = suture, syndesmosis (fibrous joint held together by ligs or strong membrane)
STRUCTURE:
- bones joined by dense connective tissue
MOVEMENT:
- tend to be immoveable
general structure + relative amount of movt: cartilaginous joint
cartilaginous - primary cartilaginous/synchondrosis, secondary cartilaginous/ symphysis
STRUCTURE:
Cartilaginous (fibrocartilaginous): bone joined by hyaline cartilage
- E.g. primary synchondrosis (b/w the ends of the bones involved is a continuous layer of hyaline cartilage) = immovable as plate of hyaline cartilage is relatively rigid e.g. growth plates in long bones (physes),
- E.g. secondary symphysis (occur in the midline of body = slightly more specialised) = their structure allows for a small amount of controlled movt e.g. pubic symphysis, fibrocartilage pad b/w hyaline cartilage bone ends
general structure + relative amount of movt: synovial joint
- Synovial: class of freely mobile joints e.g. shoulder (most common)
- Movt limited by associated joint capsules, ligaments + muscles crossing the joint
- Articular surfaces are covered w/ articular (hyaline) cartilage = because of its hardness + smoothness enable bones to move against each other w/ min friction
- low coefficient of friction: don’t offer much resistance to movement but depends on compressive load, health of articular cartilage, synovial fluid (lubrication)
Classify synovial joints according to:
i) degrees of freedom – uniaxial, biaxial, multiaxial
Degrees of freedom (movt about how many axes):
- Uniaxial (1 degree) = hinge, pivot E.G. elbow joint
- Biaxial (2 degrees) = condyloid, ellipsoid, saddle E.G. metacarpophalangeal joint
- Multiaxial (3 degrees) = ball + socket, plane (gliding) E.G. glenohumeral joint
Classify synovial joints according to:
ii) structure – hinge, pivot, ellipsoid, condyloid, saddle, ball and socket, plane
(gliding)
Shape: hinge
- Hinge: e.g. the acromioclavicular joint
- Pivot: e.g. the atlantoaxial joint
- condyloid (joints are long + oval) e.g. radiocarpal joint
- ellipsoid (oval): e.g. also the radiocarpal joint?
- Saddle: e.g. carpometacarpal joint of the thumb
- ball + socket: e.g. hip joint, glenohumeral
- plane (flat areas on each other)
Types of Joint Movement
Active, passive
Active
- Produced by muscles - normal movement: voluntary motion
Passive
- Movt is produced by an externally applied force, no muscle activation: no contribution from subject
Define and give an example of capsular, extracapsular and intracapsular ligaments.
- Capsular ligaments - form part of and blend w/ the capsule
- Intracapsular ligaments - are wholly within the capsule
- Extracapsular ligs - cross the joint completely outside the capsule
- ligaments can be one or more of these
Explain the functions of ligaments
Function of ligaments
- Provide mechanical restraints - acting at end of physiological range to:
- prevent unwanted movt,
- limit normal movt
- Contain sensory organs for kinaesthesis/proprioception
To improve joint stability we need good
- Joint congruency
- Passive restraints (capsule / ligaments / disc)
- Active restraints (muscles) close to the joint
Define and list 5 functions of articular discs
- Articular discs: Fibrocartilage inclusions inside synovial joints e.g. menisci (knee cartilages), acromioclavicular (part disc) and sternoclavicular joints
- Improves joint congruency (as thicker on outside + thinner on inside)
- Aids shock absorbency
- Increases area for force distribution
- Guide motion
- May divide a single joint into 2 spaces which aids ROM
Define and list the functions of bursae
Bursa (plural bursae)
- Is a synovial fluid filled sac b/w 1-3mm thick
Functions to:
- Reduce friction b/w tissues (muscle/bone; skin/muscle; muscle/muscle)
- Provide minimal shock absorbency
- Most you are born with - some develop through life because of rubbing
BONES OF SHOULDER = LOOK AT IMAGES
