The Shoulder Complex
Overview
The shoulder complex, as the name implies, is an extremely complicated region of the body. Sports using the
shoulder in repetitive activities, such as throwing, blocking, tacking, or rolling over, as in tumbling, may produce a
serious injury. Injuries to the shoulder joint usually result from its structural vulnerability coupled with its extensive
freedom of movement, and the relatively poor correlation between the articular surfaces and the great strength of some of
the surrounding musculature. Subjected to both acute and chronic problems, the shoulder complex is one of the most
difficult regions of the body to evaluate.
The athletic trainer should become familiar with the various conditions of the shoulder complex and the specific
exercises used to strengthen the various structures. Shoulder rehabilitation is highly complicated and depends on the
nature of the injury and whether surgery has been performed. The athletic trainer and the physician should work together
to develop an appropriate program that will lead to the athlete's swift and total recovery.
Introduction:
A. The shoulder complex has a great degree of mobility, which requires some compromise in
stability, thus leaving the shoulder highly susceptible to injury
I.
Anatomy of the Shoulder
1. Bones
a. Clavicle
1. Supports the anterior portion of the shoulder, keeping it free from the
thoracic cage
2. The point where the clavicle changes shape and contour presents a
structural weakness (Largest number of fractures to the clavicle
occur at this point)
b. Scapula
1. Articulating surface for the head of the humerus
2. The spine, the acromion and the coracoid process
3. The glenoid labrum increases the depth of the glenoid fossa
c. Humerus
1. Articulates with the glenoid fossa of the scapula
2. Lying between the lesser and greater tubercles is the bicipital groove
2. Articulations (four major articulations)
a. Sternoclavicular Joint: (ST Joint)
1. Only direct connection between the upper extremity and the trunk
b. Acromioclavicular Joint: (AC Joint)
c. Glenohumeral Joint: (GH Joint)
1. Ball-and-socket joint
2. Maintained by both static (capsule and ligaments) and dynamic
stabilizers (muscles)
d. Scapulothoracic Joint: (ST Joint)
1. Not a true joint
2. Scapular stabilization is critical in providing a stable base for GH
motion
3. Ligaments
a. Sternoclavicular Joint Ligaments
1. Anterior sternoclavicular: prevents upward displacement of the
clavicle
2. Posterior sternoclavicular: prevents upward displacement of the
clavicle
3. Interclavicular: prevents lateral displacement of the clavicle
b.
c.
a.
b.
c.
II.
III.
4. Costoclavicular: Prevents lateral and upward displacement of the
clavicle
Acromioclavicular Joint Ligaments
1. Consists of anterior, posterior, superior and inferior portions
2. Coracoclavicular ligament: maintains the position of the clavicle in
relation to the acromion
Glenohumeral Joint Ligaments
1. Superior glenohumeral ligament:
2. Middle glenohumeral ligament
3. Inferior glenohumeral ligament
Shoulder Musculature
Muscles acting on the Humerus: Pectoralis Major, Latissimus dorsi, Deltoid,
Suprspinatus, infraspinatus, Subscapularis, Teres Major, Teres Minor, and
Coracobrachialis
Muscles acting on the Scapula: Trapezius, Rhomboid Major, Rhomboid
Minor, Levator Scapulae, Pectoralis Minor and Serratus Anterior
Rotator Cuff: SITS muscles
d.
4. Bursae
a. Most important bursa is the subacromial bursa (subdeltoid); located between
the coracoacromial arch and the glenohumeral capsule
b. In overhead positions the subacromial bursa can become compessed under
the coracoacromial arch
5. Nerve Supply
a. Axillary (C5 – C6), Musculcutaneous (C5-C7), Subscapular (C5-C6),
Suprascapular (C5-C6), Dorsal Scapular (C5), Pectoral (C5-T1) and Radial
(C5-T1) Nerves
6. Blood Supply
a. Subclavian Artery -> Axillary Artery -> Brachial Artery
Functional Anatomy
1. Critical to maintain the position of the humeral head in the glenoid fossa especially
with overhead motions
2. The RTC muscles along with the long head of the biceps provide dynamic stability of
humeral head in the glenoid
3. Supraspinatus compresses the humeral head in the glenoid, while cocontraction of the
infraspinatus, teres minor and subscapularis, depress the humeral head during
overhead movements
4. Dynamic movement as well as stabilization of the shoulder complex requires all four
joints acting together
5. Scapulohumeral Rhythm
a. As humerus elevates to 30º there is no movement of the scapula (Setting
Phase)
b. From 30º to 90º scapula abducts and upwardly rotates 1 degree for every 2
degrees of humeral elevation
c. From 90º to full abduction the scapula abducts and upwardly rotates 1 degree
for each 1 degree of humeral elevation
Prevention of Shoulder Injuries
1. Strengthening through full range of motion of all the muscles involved in movement
of the shoulder complex is essential
2. Perform a proper warm-up prior to explosive movements
3. Athletes should be instructed and drilled on how to fall properly
4. Wear protective padding in collision sports
IV.
V.
5. Teach proper techniques and biomechanics related to sport specificity
Assessment of the Shoulder Complex
1. History
2. Observation
3. Palpation
4. Special Tests
a. Active and Passive ROM
b. Muscle Testing
c. Tests for Glenohumeral Instability
1. Load and Shift Test
2. Sulcus Test
d. Apprehension Test and Relocation Test
e. Tests for Supraspinatus Muscle Weakness
1. Drop Arm Test (Figure 22-17A)
2. Empty Can Test (Figure 22-17B)
f. Tests for Serratus Anterior Muscle Weakness
1. Push-up movement against the wall – winging of one scapula can
indicate injury to long thoracic nerve
g. Tests for Biceps Irritation
1. Yergason’s Test (Figure 22-19A)
h. Sensation and Circulation Testing
Recognition and Management of Specific Injuries
1. Clavicular Fractures
2. Scapular Fractures
3. Fractures of the Humerus
a. Humeral Shaft
b. Proximal Humerus
c. Epiphyseal Fracture
4. Sternoclavicular Sprain
5. Acromioclavicular Sprain
a. Contusions to the distal end of the clavicle
6. Glenohumeral Joint Sprain
7. Acute Subluxations and Dislocations
a. Subluxations
b. Anterior Glenohumeral Dislocation
1. Bankart Lesion: Anterior defect on the labrum
2. Hill-Sachs Lesion: Defect on the posterior lateral aspect of the
humeral head
3. SLAP Lesion: Defect caused by an injury to the superior aspect of
the labrum
c. Posterior Glenohumeral Dislocation
8. Chronic Recurrent Instabilities of the Shoulder
a. Recurrent Anterior Instability
b. Recurrent Posterior Instability
c. Multidirectional Instability
9. Shoulder Bursitis
10. Frozen Shoulder (Adhesive Capsulitis)
11. Thoracic Outlet Compression Syndrome
a. Compression of neurovascular bundle between the first rib and clavicle
(costoclavicular syndrome)
b. Compression between the anterior and middle scalene muscles
VI.
c. Compression by the pectoralis minor muscle as the neurovascular bundle
passes beneath the coracoid process or between the clavicle and first rib
12. Biceps Brachii Ruptures
13. Bicipital Tenosynovitis
14. Contusions of the Upper Arm
15. Peripheral Nerve Injuries
Throwing Mechanics
1. Wind-Up Phase
a. From first movement until the ball leaves the gloved hand
2. Cocking Phase
a. Begins when the hands separate and ends when maximum external rotation
of the humerus has occurred
3. Acceleration Phase
a. From maximal external rotation until ball release
b. Velocities approach 7,000 degrees per second with a force approaching 800
N
4. Deceleration Phase
a. Lasts from ball release until the shoulder reaches maximal internal rotation
b. External rotators contract eccentrically
5. Follow-Through Phase
a. Lasts from maximum shoulder internal rotation until the end of motion –
when athlete is in a balanced position