Anatomy Exam 4 - Ligaments & Extra

Scapulohumeral Rhythm

• synergistic relationship

• generally accepted ratio is 2 to 1 – for every 2 degrees of glenohumeral motion, there is 1 degree of scapular motion

Characteristics of the Shoulder Joint (GH joint)

• Wide range of motion of the shoulder joint in many different planes requires a significant amount of laxity

• The price of mobility = reduced stability

Common Instability Problems of the GH Joint

• Rotator cuff impingement

• Subluxations

• Dislocations

Normal GH Flexion

0-180 degrees

Normal GH Extension

40-60 degrees

Normal GH Abduction

0-180 degrees

Normal GH Internal Rotation

70-90 degrees

Normal GH External Rotation

70-90 degrees

Normal GH Horizontal Abduction

45 degrees

Normal GH Horizontal Adduction

130-135 degrees

GH Joint Problems

Frequently Injured due to Design:

• shallowness of glenoid fossa

• laxity of ligamentous structures

• lack of strength and endurance in muscles

• anterior or anteroinferior glenohumeral subluxations and dislocations are common

• posterior instability problems somewhat common

• posterior dislocations are rare

GH Joint - Common Pathologies

1) Tendonitis - inflammation of tendon

• biceps tendon (long head), supraspinatus tendon, infraspinatus tendon

2) Rotator Cuff Injuries

• made up of supraspinatus, infraspinatus, teres minor, subscapularis

3) Impingement Syndrome - Tendons become irritated and inflamed as they pass through the subacromial space

• Supraspinatus and Infraspinatus = Most commonly affected

• can cause frozen shoulder

4) GIRD (Glenohumeral internal rotation deficit)

• difference in internal rotation range of motion between an individual’s throwing and non throwing shoulders

• overhead athletes with a gird of greater than 20% had a higher risk of injury