HMB470 Lecture 10 study guide top-rated

3 articulations form synovial joints - - gleno-humeral (GH joint = the main "ball and socket" / enarthrosis) - sterno-clavicular (also 3 DoF, 2 significant, 1 limited) - acromio-clavicular (also 2 DoF, all 3 limited) 2 shoulder motion components - - scapulo-humeral (GHJ movement) - scapulo-thoracic (combines movement of SCJ, ACJ, and C-T spine) ISB JCS for GH Joint - • horizonal ab-adduction (Yp) bi-polar axis -lines of latitude • internal-external rotation (Yd)= long axis of humerus, axial rotation of humerus • elevation (F) = floating axis -lines of longitude • gimbal lock in AnPos(Yp=Yd) Scaulothoracic movements - Elevation -component of total shoulder elevation rotation in the scapular plane accomplished mostly by SC elevation Protraction -retraction: compound / multi-joint multi-axial translation + multi-planar rotation Shrug -compound / multi-joint vertical translation Constraints of Isolated GH RoM - GH Elevation is (always in everyone) constrained by subacromial impingement - humeral head vs. acromion - interposed tissues: cuff, bursa, tendon of long head of biceps - earlier constraint if humerus is in IR (greater tuberosity on top) GH HAd is constrained by coraco-acromial impingement GH HAb and GH IR-ER constrained by ligamentous capsulo-labral complex IGHL (inferior glenohumeral ligament) constrains Gh EHAbER - GH ligaments are lax in neutral position or GHJ would not move! IGHL tightens with elevation, migrates anteriorly with ER, tightens with HAb Constrains GH EHAbER ("wind-up") Constraints of GH Translation - Anterior, posterior, inferior and lateral translation of humerus constrained by capsulo-labral complex