1. Shoulder Biomechanics

2. Sternoclavicular and Acromioclavicular Joints
SC Joint
Saddle-type, but functions as ball & socket
4 ligaments
Strong, but MOBILE
ROM=60° elevation and 25-30° anterior and posterior movement
AC Joint
Plane synovial articulation
Axioappendicular muscles cause acromion of scapula to rotate on acromial end of clavicle, which increases scapulothoracic joint movement
SC Joint:
Saddle-type joint, but functions as ball and socket
2 compartments divided by an articular disc
Strong ligamentous attachments: dislocation of clavicle=unusual
fracture of clavicle=common
Surrounded by joint capsule with synovial membrane
4 ligaments: anterior sternoclavicular ligament
posterior sternoclavicular ligament
both reinforce joint capsule anteriorly and posteriorly
interclavicular ligament strengthens capsule superiorly (sternal end to sternal end and over the superior border of the manubrium)
costalclavicular ligament limits elevation of pectoral girdle (inferior surface of sternal end to 1st rib and its costal cartilage)
Strong, but MOBILE
ROM=60° elevation and 25-30° anterior and posterior movement
AC Joint:
Plane synovial articulation
Articular surfaces of acromion and clavicle are separated by an articular disc
Sleeve-like joint capsule with synovial membrane WEAK! –strengthened by trapezius fibers
4 ligaments: acromioclavicular ligament (acromion->clavicle) strengthens superiorly
coracoclavicular ligament STRENGTH –prevents acromion from being drawn under clavicle (clavicle->coracoid process of scapula)
conoid ligament (coracoid->conoid tubercle)
trapezoid ligament (coracoid->trapezoid line)
both provide the means at which the scapula and free limbs are (passively) suspended from the clavicle
Axioappendicular muscles cause acromion of scapula to rotate on acromial end of clavicle, which increases scapulothoracic joint movement

3. Glenohumeral Joint (scapulohumeral &scapulothoracic)
Ball & socket synovial joint
WIDE ROM, mobile, UNSTABLE
Cavity only accepts 1/3 of humeral head
Held in cavity with rotator cuff muscles
3 ligaments
Most freedom in body
Lateral rotation of humerus increases abduction ROM
Ball and socket, synovial, WIDE ROM, mobile, UNSTABLE
Humeral head with glenoid cavity (with glenoid labrum)
Hyaline cartilage
Cavity only accepts 1/3 of humeral head
Held in cavity by rotator cuff muscles: supraspinatus, infraspinatus, teres minor, and subscapularis
Has a joint capsule with a synovial membrane
inferior part=weakest no rotator support
lax, lies in folds: ADducted
taught: Abducted
3 ligaments strengthen anterior aspect of capsule:
coracohumeral ligament STRONG –strengthens superiorly (coracoid process->anterior aspect of greater tubercle
transversehumeral ligament BROAD (greater tubercle->lesser tubercle) -bridges over intertubercular groove
coracoacromial ligament overlies head of humerus (coracoid->acromion) –prevents superior displacement from GH cavity
***coracoacromial arch is so strong that a forceful superior thrust of humerus will not fracture it!
-shaft of humerus or clavicle fracture first!
Most freedom in body laxity of joint capsule and bony fit movement in 3 axes (flex, ext, AB, AD, med rot, lat, rot, and circumduction)
Lateral rotation of humerus increases abduction ROM (greater tubercle does not hit coracoacromial arch –shifted posteriorly)
Stiffening or fixation of joints of the pectoral girdle results in a much more restricted ROM, even if the GH joint is normal
Axioappendicular muscles move joint indirectly (pectoral girdle)
Scapulohumeral muscles move the joint directly
Shunt muscles: act to resist dislocation without producing movement at the joint, or maintain the head of humerus in the GH cavity
ex: deltoid when arms are at side
Usually all joints move simultaneously . Functional deficits in any impair overall pectoral girdle ROM. Mobility of the scapula is essential for elevation. The initial 30° of ROM can occur without scapular motion in elevation, but then a 2:1 ration occurs. Scapulohumeral Rhythm=for every 3° of elevation, 2° occurs at the GH joint and 1° occurs at the ST joint.

4. Clavicular Elevation (SC joint)
Elevation & Depression
Clavicular elevation /depression(SC)
Subtle anterior/posterior tipping (AC)
Subtle internal/external rotation (AC)
Upward & Downward Rotation (abd/add)
2:1 humoral:scapular
Upward/downward rotation (AC)
Clavicular elevation/depression (SC)
Subtle posterior/anterior rotation (SC)
Protraction & Retraction
Clavicular protraction/retraction (SC)
Winging
Excessive internal rotation (AC)
Scapula loss of contact with thorax, medial border prominence results
Clavicular Elevation (SC joint)
Winging
Upward Rotation (AC)
Protraction (SC)

5. Hawkins-Kennedy Test Neer Impingement Test
Group 1
Group 2
Group 3
Group 4
Trunk to Head
Trunk to scapula
Trunk to Humerus
Shoulder Girdle to Humerus
SCM
Subclavius
Trapezius
Levetor scapulae
Serratus anterior
Rhomboids major & minor
Pectoralis minor
Latissimus dorsi
Pectoralis major
Deltoideus
Subscapularis*
Supraspinatus*
Infraspinatus*
Teres minor*
Teres major
Scapular Movement
Muscles Producing Movement
Elevation
Trapezius (superior part)
Levator Scapulae
Rhomboids
Depression
Pectoralis major (inferior sternocostal head)
Latissimus Dorsi
Trapezius (inferior part)
Serratus anterior (inferior part)
Pectoralis minor
Protraction
Serratus anterior
Pectoralis major/minor
Retraction
Trapezius (middle part)
Latissimus dorsi
Upward Rotation
Downward Rotation
Levator scapulae
Tests:
Hawkins-Kennedy  Test Neer Impingement Test

6. Research Article
Evaluated the effectiveness of FES in shoulder subluxation and pain for patients who have developed hemiplegia due to stroke
Shoulder pain measured during resting, passive range of motion (PROM) and active range of motion (AROM) using visual analog scale (VAS)
50 patients with shoulder subluxation and shoulder pain randomly split into either the study group or the control group
FES applied to supraspinatus and posterior deltoid muscles
Study groupconventional rehabilitation therapy and applied FES
Control group conventional rehabilitation therapy
Results decreased subluxation levels in the study group compared to the control group
Conclusion Conventional therapy with FES is more beneficial than just conventional therapy alone when examining shoulder subluxation
This article looks at the effects of functional electrical stimulation (FES) for the treatment of shoulder subluxation and shoulder pain in hemiplegic patients
Subluxation is partial or incomplete dislocation. The humeral head slips out of the glenoid cavity due to weakness in the rotator cuff or a force/blow to the shoulder area
The term hemiplegic means paralysis of one side of the body, and in this case, is due to trauma, stroke or tumors.
Functional electrical stimulation (FES) is the “stimulation of muscles with disturbed nerve function by an electrical current to achieve functional and beneficial movement”
 The effectiveness of functional electrical stimulation for the treatment of shoulder subluxation and shoulder pain in hemiplegic patients: A randomized control trial
Koyuncu, E., Nakipoglu-Tuzer, G., Dogan, A., and Ozgirgin, N. (2010). The effectiveness of functional electrical stimulation for the treatment of shoulder subluxation and shoulder pain in hemiplegic patients: A randomized controlled trial. Disability and Rehabilitation, 32 (7),

7. Shoulder Instability
Most common are anterioinferior capsololabral auvlsions (Degen,2013), more commonly known as Bankart Lesions
Glenoid Bone Grafting
Bristow Coracoid Transfer
Latarjet Coracoid Transfer (subscapularis)

8. References
Degen, R. M., Giles, J. W., Thompson, S. R., Litchfield, R. B., & Athwal, G. S. (2013). Biomechanics of Complex Shoulder Instability. Clinics In Sports Medicine, 32(4), doi: /j.csm
Itoi E, Lee SB, Berglund LJ, et al. (2000). The Effect of a Glenoid Defect on Anteroinferior Stability of the Shoulder After Bankart Repair: a cadaveric study. J Bone Joint Surg Am,82(1), 35–46.
Koyuncu, E., Nakipoglu-Tuzer, G., Dogan, A., and Ozgirgin, N. (2010). The effectiveness of functional electrical stimulation for the treatment of shoulder subluxation and shoulder pain in hemiplegic patients: A randomized controlled trial. Disability and Rehabilitation, 32(7),
Moore, K., Agur, A., and Dalley, A. . (2015). Essential Clinical Anatomy. Lippincott Williams & Wilkins, 5,
Netter. F. (2014). Atlas of Human Anatomy. Saunders Elsevier, (6), , 417
Tortora, G., Derrickson, B. (2012) Principles of Anatomy and Physiology. Biological Science Textbook Inc, 13,