Shoulder Complex

Shoulder Complex

1. Comprised of: 1) Scapulo-thoracic junction 2) Glenohumeral Joint 3) Acromio-clavicular joint 4) Sterno-clavicular joint

   • Scapula-thoracic Junction
     • Does not have the common characteristics of a synovial joint therefore it is not a true articulation.
     • Provides stability to the GH joint.

2. Position of Scapular-thoracic Junction

   • Normal resting position is in an oblique angle to the frontal plane.
     • Lateral border of scapula is angled anterior 30-45 degrees from frontal plane. Upwardly rotated 10-20 degrees and anteriorly tipping ~ 10-20 degrees.
   • Movement
     • The scapula moves around a dorso-vental axis, resulting in rotation in the frontal plane.
     • Scapulohumeral Rythm
       • Phase 1: 0-30 degrees of ABD - Humerus 30/ Clavicle 0-5 elevation/ Scapula minimal medially
         • Phase 2: 30-90 degrees of ABD - Humerus/Scapula = 2:1 - Humerus 40 ABD/ Scapula 20 ER/ Clavicle 15 elevation
           • Phase 3: 90-180 degrees - Humerus 60 ABD & 90 ER/ Scapula 30-40 ER/ Clavicle 30-50 posterior rotation & 15 elevation

3. Force Couple of Scapula-thoracic Junction

   • Defined as a relationship of multiple muscles working together
   • Deltoid and Rotator CUff
     • 1) Scapula-humeral muscles not scapula-thoracic. 2) The RTC acts primarily as a stabilizer while the deltoids function as the mover. The RTC provides normal compressive force of humeral head into the glenoid fossa. If the deltoids were stronger than the RTC the result would be upward/superior migration of the humeral head during arm movements causing pathological compression of the greater tuberosity of the humerus into the underside of the coraco-acromial carch. 3) Poor strength ratios of the deltoid and RTC will impact a person's ability to raise their arm in ANY PLANE.
   • Upper + Lower Trapezius + Serratus Anterior
     • 1) Elevation requires upward rotation of the scapula. 2) Upward rotation occurs secondary to contractile pull of the Upper Trap and Serratus Anterior.
       • 4 Functions
         • 1) Maintains anterior-lateral position of glenoid surface allowing rotation of scapula.
           • 2) Maintains efficient length tension relationship for the deltoid.
             • 3) Prevents impingement of the RTC from the coraco-acromial arch.
               • 4) Stabilizes the scapula during movement to allow for the recruitment and action of the scapula-humeral muscles
   • Anterior and Posterior Rotator Cuff
     • Functions to maintain stability throughout ROM at the glenohumeral joint.
       • Collectively the muscles depress the humeral head away from the coracoacromial arch while creating compression of the humeral head into the glenoid fossa.
         • The RTC musculature seats the humeral head within the concavity created by the glenoid labrum.
           • The subscapularis (anterior RTC), the infraspinatus and teres minor (posterior RTC) are particularly important in maintaining GH depression and compression.

4. Glenohumeral Joint

   • ○ The primary stability at the shoulder does not come from the osseous components of the scapula
     • ○ The humeral head is 3-4x larger than the shallow concave glenoid fossa
       • Humeral head faces posteriorly/medially/superiorly
         • ○ Glenoid fossa faces lateraly/slight posterior orientation referencing the scapula alone, but relative to the frontal plane facing ~30 degrees anterior/ tilted superiorly
           • ○ The superior placement of the glenoid fossa and the humeral head may contribute to stability in the inferior direction.

5. Acromioclavicular joint

   • Synovial, planar joint
     • ○ Relies on the AC and coracoclavicular(CC) ligaments
       • ○ Stability of the AC joint comes by an articular disc between each articular surface
         • ○ Treatment plane may vary depending on the particular facet that each have their own articular surfaces § Superior-posterior to inferior-anterior § Superior-posterior with medial direction to inferior-anterior with a lateral direction § Superior-posterior with lateral direction to inferior-anterior with a medial direction

6. Sternoclavicular Joint

   • ○ Saddle joint ○ Unstable to minimal to no musculature stability, however one of the least dislocated joints in the body.

Bilder und Dateien der Mindmap

• Scapulohumeral Rhythm (Einbetten)