1. Upper
Extremity
Shoulder Complex
Elbow
Wrist
(Hand)
Shoulder

2. Shoulder Complex sternoclavicular acromioclavicular coracoclavicular
scapulothoracic
glenohumeral

3. Shoulder Girdle sternoclavicular jt acromioclavicular jt
an “open” mechanical system
R and L sides not directly attached so can move independently
sternoclavicular jt
acromioclavicular jt
scapulothoracic jt

4. Sternoclavicular Articulation
site of most movement of shoulder girdle
elevation/depression (up and down, 30-40o)
rotation (40-50o)
protraction/retraction (A/P, rowing, 30o)
articulation between the sternum and clavicle
a modified ball-and-socket joint
mobile in frontal and transverse plane
limited sagittal movement
Interclavicular
Ligament
Clavicle
Clavicle
Sternoclavicular
Ligament
Articular
disk
Costoclavicular
Ligament
Costal
cartilage
Sternum

5. Acromioclavicular Articulation
articulation between acromion process and distal end of clavicle
coracoclavicular ligament
serves as axis of rotation for
associated scapular mvmts
very dense capsule + AC ligaments
provide support
Bony Support -- WEAK!

6. AC Mvmts 3 df protraction/retraction: acromion process
moves on meniscus, scapula rotates
about medial coracoclavicular ligament
(conoid) º
upward/downward rotation: clavicle
about lateral coracoclavicular
ligament (trapezoid) 60º
elevation/depression: relative motion of
acromion & clavicle with no rotation
30º
AC Mvmts
Note: AC joint will be
opposite those at SC joint
(e.g., AC elevation -- SC depression)

7. Scapulothoracic Articulation
“physiological” articulation (no bone-to-bone connection) between the anterior surface of the scapula (scapular fossa) and the thoracic wall
scapula rests on 2 muscles (serratus anterior and subscapularis)
60º ROM
Shoulder

8. Shoulder Joint (aka glenohumeral) - articulation of humerus and
glenoid fossa
- designed for mobility
(greatest ROM of any jt
in body)
- lacks bony and ligamentous
support
- shallow glenoid fossa
(1/4 size of humeral head)
-half-spherical humeral head

9. Supporting Structures for Shoulder
labrum
a lip of cartilage surrounding the joint
increases depth of fossa
increases contact area by 75%
assists in holding the humerus in place

10. coracohumeral
ligament
glenohumeral
ligaments
superior
middle
inferior
these ligaments
merge with the
articular capsule

11. Shoulder depends on ligamentous and muscular contributions for support
articular capsule
2X volume of humeral
head - laxity
anterior support
capsule, labrum, glenohumeral
ligaments 3 “reinforcements” in
the capsule coracohumeral
ligament, and fibers of the
subscapularis and pec. major
that blend into the jt capsule
posterior support
capsule, labrum, fibers from
the teres minor &
infraspinatus that blend into
the capsule

12. Shoulder Ligamentous Support
no ligament to prevent backward displacement
fossa angle slightly anterior
prevents backward displacement
Shoulder

13. Subacromial Arch
coracoacromial
ligament
provides a “buffer”
for the rotator cuff
muscle tendons

14. Rotator Cuff Muscles (S I T) Infraspinatus Subscapularis Supraspinatus
3 originate
on posterior
scapula
(S I T)
4th originates
on anterior
scapula
Teres Minor

15. Stabilizing Influence of Rotator Cuff
muscles have a large stabilizing component when active
all have a ‘large’ horizontal component
so play a significant role in stabilizing the humerus against the glenoid fossa

16. Bursae in Shoulder sacs secreting synovial fluid
distributed throughout shoulder complex to reduce friction between tissues
e.g. subacromial bursae
cushions rotator cuff muscles (supraspinatus) from laying directly on acromion process
overuse can lead to irritation of bursae
Shoulder

18. 2) humeral head stabilization 3) orienting the glenoid fossa
Abduction/Flexion
1) primary movers
2) humeral head stabilization
3) orienting the glenoid fossa

19. Abduction/Flexion
1) Primary movers
deltoid ~50%, rotator cuff ~50%

20. Abduction/Flexion 2) humeral head stabilization
early: teres minor depresses head
late: subscapularis & infraspinatus
stabilize head
>90º: supraspinatus remains active

21. Scapulohumeral Rhythm
scapular rotation to facilitate shoulder movements (abduction & flexion)
1st 30 º of abduction or 45º of flexion -- scapula moves to a position of stability on thorax
beyond this initial range -- a 5:4 ratio of glenohumeral to scapular movements
for total ROM have a 2:1 ratio (e.g. 180 º of abduction have 120 º of glenohumeral mvmt and 60 º of scapular mvmt.

22. Abduction/Flexion 3) orienting the glenoid fossa
requires protraction, elevation, upward
rotation with posterior clavicular rotation
upper trapezius and serratus anterior
responsible muscles

23. Adduction & Extension sternal portion of pectoralis major
Primary Movers: If no resistance then use eccentric actions of abduction/ flexion muscles BUT if resistance (e.g. weight machine or swimming) main contributors are
sternal portion of
pectoralis major
latissumus dorsi
teres major

24. Adduction & Extension Accompanying movements: retraction, depression,
downward rotation with anterior clavicular rotation
Pectoralis minor
depresses &
downwardly rotates
Rhomboid
downwardly rotates
& retracts
Mid & lower trapezius
retracts

25. Internal & External Rotation
Important to many sport skills plus a necessary
movement to accommodate mvmt when arm is at
90º or greater abduction or flexion
External rotation: infraspinatus & teres minor primary muscles on posterior side
insert posteriorly on humerus
Internal rotation: subscapularis & teres major
primary muscles on anterior side
insert posteriorly on humerus
(also lat. Dorsi and pect. major)

26. Horizontal Ab-/Adduction
Similar musculature as for flexion and abduction
BUT more sig. contribution from
pec. major & ant. deltoid for hor. adduction
infraspinatus, teres minor, & pos. deltoid for hor. abduction

27. Muscular Strength Shoulder Complex
adduction
extension
flexion
abduction
internal rotation
external rotation
STRONGEST
WEAKEST

28. Loads on Outstretched Arms
T = Fd
moment arms
a = 0 cm
b = 20 cm
c = 30 cm
shoulder torque
A. 0 N cm
B. 700 N cm
C N cm C
The moment arm(d) is the
perpendicular distance
from the line of action of the
weight to the axis of rotation. B A
if segment weight = 35 N c b

29. Shoulder Loading
ergonomists recommend workers seated at desk use arm position with 20 degrees or less of abduction and 25 degrees or less of flexion

30. Shoulder Girdle Injury
sternoclavicular joint
low rate of injury
sprain caused by force which displaces shoulder anteriorly
dislocation of medial end of clavicle medially, superiorly, and either anterior or posterior
posterior dislocation particularly dangerous because trachea, esophagus, veins, etc. located behind
dislocation in adults but usually fracture in children
Shoulder

31. Shoulder Girdle Injury
acromioclavicular joint
force applied laterally to acromion process
commonly known as shoulder separation
range from mild sprain of AC ligament to complete AC dislocation with tearing of clavicular attachments of deltoid and trapezius & complete rupture of coracoclavicular ligament
displaces the acromion anteriorly and inferiorly while clavicle does not move (95% of all dislocations for this joint)
scenario - fall on an outstretched arm to break a fall
force of impact transmitted through humerus such that entire scapula is displaced relative to unmoved clavicle
Shoulder

32. Shoulder Injuries Dislocation or subluxation
frequent due to lack of stability
usually occur when shoulder abducted and externally rotated
anterior-inferior dislocations most common (90%)
when arm is abducted, extended, and externally rotated
usually caused by a large external force
age of 1st dislocation inversely related to rate of recurrence
i.e. the younger you are the more likely you are to have a recurrence
Shoulder

33. Detecting a torn Rotator Cuff Tendon using an Arthrogram
Inject dye into joint to see if it leaks out where the rotator
cuff tendon is supposed to be

34. Detecting a torn Rotator Cuff Tendon using an MRI

35. Often associated with overarm motions such as throwing
Soft tissue injuries
Often associated with overarm motions such as throwing
Preparatory phase -- shoulder abducted to 90, shoulder ext rotation, scapular retraction, and elbow flexion
Anterior capsule and
subscapularis muscle are
susceptible to strain or tendinitis
at the insertion on the lesser
tubercle

36. Extreme External Rotation in Overarm Pitching
external rotation terminated by forces from
anterior joint capsule & ligaments
subscapularis
pectoralis major
triceps brachii
teres major
latissimus dorsi

37. Acceleration Phase explosive phase characterized by
initiation of elbow extension
shoulder internal rotation
maintenance of shoulder abduction at 90
shoulder transverse adduction
scapular protraction
posterior capsule and labrum susceptible to injury as anterior shoulder is tightened driving the humeral head backwards

38. Follow-Through Phase
Rotator cuff works to decelerate shoulder’s internal rotation
infraspinatus and teres minor very susceptible to muscle strain or tendinitis

39. Rotator Cuff Impingement
impingement of supraspinatus tendon
2 theories
GENETIC: too narrow a space between acromion and humeral head
OVERUSE: repeated stretching of supraspinatus weakens its ability to stabilize the humerus leading to deltoid pulling humerus up and impingement of tissues

40. Swimmer’s Shoulder recovery
near maximum tension in serratus anterior during recovery to rotate scapula and facilitate overhead arm movements
fatigued serratus will not rotate scapula so rotator cuff muscles impinged
Shoulder

41. Swimmer’s Shoulder “Impingement Syndrome”
@ hand entry
shoulder forced into extreme abduction, flexion and internal rotation
allows prox head of humerus to rub across the supraspinatus tendon
can “impinge” the supraspinatus tendon between humerus and coracoacromial ligament
increased internal rotation when elbow is held in place and arm pushes back
head of humerus is thrust forward close to ligamentous structure of shoulder joint where contact can occur
increase likelihood of impingement
Shoulder

42. Swimmer’s Shoulder (cont.)
at completion of arm pull
shoulder adducted such that supraspinatus tendon is stretched over the head of the humerus
cuts off blood supply to tendon
Shoulder