The Shoulder Complex
(Shoulder Girdle and Glenohumeral Joint)

Specific Readings:
Behnke: pgs. 35-62
Thompson and Floyd: pgs. 57 - 102

- Joint Type- Ball-&-Socket, allows for more movement

- Scapula & Clavicle

- 180° of movement in girdle and shoulder joint

Bones:

Scapula, Clavicle, Humerus, and Sternum

Joints:

Synovial: Glenohumeral, Acromioclavicular, Sternoclavicular

Bone-Muscle-Bone: Scapulothoracic Articulation

I. Sternoclavicular Joint

-         Between medial clavicle and superior lateral manubrium

-         Only joint between arm and upper body

Ligaments

1. Interclavicular: superior manubrium between each clavicle

2. Sternoclavicular- Anterior & Posterior: sternum and end of clavicle

3. Costoclavicular: medial end of clavicle to first rib

ROM:

II.  Acromioclavicular Joint

-         Acromion process of scapula and lateral clavicle

-         Synovial joint

Ligaments

1.  Inferior & Superior Acromioclavicular

2.  Coracoclavicular

Trapezoid:

Conoid:

III. Scapula thoracic Articulation

-         Scapula and torso

-         Not a true joint-no direct connection, only via muscle (serratus anterior and subscapularis between scapula and thorax)

Bone-muscle-bone articulation:

Muscles of the Shoulder Girdle:

• Elevation:
• Depression:
• Protraction (abduction):
• Retraction (adduction):
• Elevation w/ upward GH rotation:
• Depression w/ downward GH rotation:

IV. Glenohumeral Joint

-         Head of humerus and glenoid fossa of scapula

• Joint Capsule

• Glenoid Fossa (Cavity)

• Labrum

Ligaments

1. Superior Glenohumeral Ligament

2. Medial Glenohumeral Ligament

3. Inferior Glenohumeral

4. Coracoacromial Ligament

5. Coracohumeral (anteriorly)

6. Transverse humeral

Muscles

Rotator Cuffs: Supraspinatus, Infraspinatus, Teres Minor, & Subscapularis

Important factors for stability of GH joint:

1.      Having adequate glenoid fossa size

2.      Having superior and posterior tilt of glenoid fossa

3.      Having intact joint capsule and glenoid labrum

4.      Appropriate function of muscles that control anterior and posterior positioning of humeral head

• The muscles that act on the humerus, must act in concert with other muscles around the joint in order to prevent producing a dislocating force

• Many muscles crossing the GH joint also cross other joints; which usually change confirmation or position. If other joints change position, the muscles will change the GH joint position as well

• Due to shoulder’s large ROM, position of shoulder actually changes muscle motion on humerus

Slide                   

Just Gravity-                                          vs.                When Loaded-

Capsular passive tension,                                       Active supraspinatus

coracohumeral ligament, and                                  and posterior deltoid to

Inactive supraspinatus                                              keep inferior movement of joint

• Electromyography (EMG)

Muscle Analysis of Swimmers

Innervation of Shoulder

Brachial Plexus

• Supraclavicular – Brachial plexus above clavicle
• Infraclavicular – Brachial plexus underneath corocoid process and pectoralis minor

Supraclavicular Nerves:

1. Dorsascapular N
2. Long Thoracic N
3. N to subclavius
4. Suprascapular N

Infraclavicular Nerves:

1. Lateral Pectoral N
2. Medial Pectoral N

Posterior Cord Nerves:

1. Upper Subscapularis N
2. Axillary N
3. Thoracodorsal N
4. Lower Subscapular N

Injuries to Brachial Plexus

Mostly happens when head and shoulder become stretched (separated)

-          Partial Paralysis –If some of ventral rami are injured

-          Complete paralysis – All ventral rami damaged – paralysis of arm

-          Loss of sensation

Innervation of Shoulder

Innervation by Nerve:

C5                                           C6                                           C7

All Except:                              All Except:                              Long Thoracic

Medial Pectoral                     Dorsascapular                       Lateral Pectoral                    

Thoracodorsal                       Medial Pectoral                     Thoracodorsal

C8                                           T1

Medial Pectoral                     Medial Pectoral

Thoracodorsal