AC Joint Flashcards
what 2 structures make up the AC joint?
lateral clavicle + acromion of scapula
what type of joint is the AC joint?
planar synovial
What are the articulating surfaces of the AC joint? Are they congruent or incongruent?
- lateral end of clavicle + small facet on acromion
- surfaces are incongruent
true or false: the AC joint disc may not be present in all bodies
true, it varies from person to person
what are 2 common causes of AC joint dislocation?
- FOOSH (falling on outstretched hand)
- falling directly onto the joint
AC joint pain is very ____
- specific
- pt will usually point directly at the joint when describing their pain
what is the primary function of the AC joint?
- allows scapula to rotate during arm movement
- increases UE motion
- positions glenoid beneath humeral head
- maintains congruency of scapula on thorax
OK of the AC joint
- IR/ER
- ant/post tilting (tipping)
- upward/downward rotation
the scapular plane is ____ degrees off the ____ plane
- 35
- frontal
why is IR/ER of AC joint important?
helps maintain contact of scapula on curved thorax during protraction/retraction of clavicle
why is ant/post tilting of the AC joint important?
helps maintain contact of scapula on curved thorax during elevation/depression of clavicle
why is upward/downward rotation of the AC joint important?
helps for positioning glenoid fossa in optimal position
Describe what occurs during upward rotation of the AC joint
scapula swings upwardly & outwardly during ABD or FL of shoulder
Describe what occurs during downward rotation of the AC joint
brings scapula back to anatomical position during ADD or EX of shoulder
What is the closed pack position of the AC joint?
full upward rotation
-occurs in flexion or ABD
