functional anatomy of shoulder girdle

Abstract

Functional anatomy of shoulder girdle

1. first link in a chain of levers from shoulder to fingertips 2. lots of motion possible - price is stability 3. natural diminition in ROM with aging 4. simple ADLs generate 3000-4000 shoulder movements per day

Movement A. flexion - forward elevation in the plane of the scapula is the most functional form - supra and deltoid are optimally aligned for elevation. (180) muscle - anterior deltoid, coracobrachialis, clacicular fivers of pec major, long head of the biceps limiting factors - coracohumeral lig. resistance from teres monor and major, infraspinatus B. Internal / external rotation (90 degree in each direction) 1. internal rotators : latissimus dorsi, teres major, subscapularis, pectoralis major 2. external rotators : infraspinatus, teres minor a. weak in comparison to medial rotators b. different nerve supply, but same root level (C5, 6 ) C. Adduction ( 75 degree) 1. muscles : teres major, latissimus, pectoralis major, rhomboids 2. couple formed by rhomboids and teres major : rhomboids prevents scapular roation upwards and allows teres major to adduct 3. couple formed by long head of the triceps and latissimus dorsi : triceps opposes inferior displacement of humeral head by strong latissimus action D. Extension (60 degree) 1. muscles : teres major, minor, posterior fibers of deltoid, latissimus dorsi 2. for extension at the scapulothoracic joint, by adduction of the scapula, also need rhomboids, middle transverse fibers of the trapezius, latissimus dorsi