1. The Shoulder Joint (Glenohumeral Joint)
What bones make up the shoulder joint?
Clavicle
Scapula
Humerus
Joint involved
The shoulder joint is made up of the
glenohumeral joint. This is an enarthrodial,
or multiaxial, ball and socket joint. It is
very mobile, but sacrifices stability.

3. The Shoulder Joint Many variable movements occur at the shoulder.
Movement of the humerus usually involves
movement at the shoulder girdle, known as
“scapulohumeral rhythm.”
What are the 8 movements that occur at the
shoulder joint?
Abduction
Adduction
Flexion
Extension
Horizontal abduction
Internal Rotation
External Rotation
Horizontal adduction

4. The Shoulder Joint To study the 9 muscles of the shoulder joint,
we will break them into intrinsic and extrinsic
groups. The intrinsic group originate on the
clavicle and scapula.
What are the 7 intrinsic muscles of the shoulder
joint?
Supraspinatus
Infraspinatus
Subscapularis
Teres minor
Coracobrachialis
Deltoid
Teres major

5. The Shoulder Joint Intrinsic muscles of the shoulder joint
What are the two extrinsic muscles of the
shoulder joint?
Latissimus dorsi
Pectoralis major
Intrinsic muscles of the shoulder joint
The first group of intrinsic muscles are the SITS
muscles. The band of tendons of these four
muscles compose the rotator cuff of the shoulder
joint. The functions of the SITS muscles include
rotation of the humerus, and to provide stability,
especially against subluxation.

6. Rotator Cuff

7. Supraspinatus

8. The Shoulder Joint A. Supraspinatus muscle - This muscle is most
superior of the rotator cuff. It pulls the head
of the humerus into the glenoid fossa to
initiate abduction and provide an effective
angle of pull for the deltoid. It helps reinforce
the shoulder joint.
Actions - assist abduction, stabilize head of
humerus

9. The Shoulder Joint Testing the supraspinatus for injury
1. Resisting against abduction - if the patient has
trouble abducting the arm against resistance
and tries to substitute the scapular muscles, it
can indicate supraspinatus damage.
2. Drop arm test - if the patient can not slowly
lower the arm from an abducted position, it
can indicate supraspinatus injury.

10. Infraspinatus

11. The Shoulder Joint B. Infraspinatus muscle - located just inferior to
the supraspinatus, it also helps reinforce the
shoulder capsule and stabilize the humerus
during abduction.
Actions of the infraspinatus
External rotation - most powerful external
rotator of SITS muscles
Extension of humerus
Horizontal abduction

12. The Shoulder Joint Exercises involving the infraspinatus
Chinning, dips, rope climbing. Any exercise
in which the arms are pulled down forcefully.
Works in conjunction with teres major and
latissimus dorsi.
Testing of the infraspinatus muscle
External rotation against resistance. Patient
lays prone with arm hanging. Fixate the scapula
and have them rotate up against resistance.

13. Teres Minor

14. The Shoulder Joint C. Teres minor - Inferior to the infraspinatus,
this muscle also reinforces the shoulder
capsule and helps stabilize the head of the
humerus during abduction.
Actions of the teres minor
External rotation
Horizontal abduction
Extension

15. The Shoulder Joint Exercises to strengthen the teres minor
Same as infraspinatus - chinning, rope climbing,
dips, any movement in which arms go down
forcefully.
Testing the teres minor
Same test as for infraspinatus, prone test
for external rotation with scapula stabilized.

16. Subscapularis

17. The Shoulder Joint D. Subscapularis - the final muscle in the four
“rotator cuff” muscles. As with the others,
helps stabilize shoulder capsule. This is the
only rotator cuff muscle to originate on the
anterior surface of the scapula.
Actions of the subscapularis
Internal rotation - main action
Adduction
Extension - from flexed position

18. The Shoulder Joint Exercises involving the subscapularis
As with infraspinatus and teres minor, it is
involved in chinning, dips and rope climbing.
A specific exercise for this muscle is internal
rotation against resistance.
Testing the subscapularis
Similar to other muscles, have the patient lay
prone, and internally rotate against resistance.

19. Deltoid

20. Shoulder Joint Muscles
Additional Intrinsic Muscles
A. Deltoid Muscle - This muscle forms the rounded
muscle bulk of the shoulder joint. It is a strong
abductor, but cannot initiate that movement
because the angle of pull is parallel to the humerus
when the arm is by the side. Recall that the
supraspinatus initiates the movement.
The deltoid muscle is divided into three portions,
and hence is sometimes called “deltoids” muscle.
The three portions are anterior, middle, and posterior.

21. Shoulder Joint Muscles
What are the actions of the anterior deltoid?
Abduction
Internal rotation
Horizontal adduction
Flexion
What are the actions of the middle deltoid?
Abduction
What are the actions of the posterior deltoid?
Abduction
External rotation
Horizontal abduction
Extension

22. Shoulder Joint Muscles
Exercises to strengthen the deltoid muscle
Bench press
Overhead press
Front arm raise
Lateral arm raise
Prone flies
Supine horizontally adducted dumbbell raises will strengthen the anterior deltoid.
Prone horizontally abducted dumbbell raises will strengthen the posterior deltoid

23. Coracobrachialis (not brachialis)

24. Shoulder Joint Muscles
B. Coracobrachialis muscle - This muscle is named
for its origin and insertion.
What actions does the coracobrachialis perform?
Adduction
Horizontal Adduction
Flexion
Exercises to strengthen would include:
When arm is abducted above 90 degrees, assists with adduction. Assists with flexion.
Floyd text suggests lat pulls for coracobrachialis – okay until arm reaches 90 degree elevation.
Bench press
Lat pulls
Supine flies
Not particularly strong, most functional in
Horizontal Adduction

25. Teres Major

26. Shoulder Joint Muscles
C. Teres Major muscle - Together with the
infraspinatus and teres minor, it helps stabilize
the humerus during abduction. It is also known
as the latissimus dorsi’s little helper.
What are the actions of the teres major?
Adduction
Internal Rotation
Extension

27. Shoulder Joint Muscles
Exercises to strengthen the teres major muscle
Rope climbing
Lat pulls
Internal rotation against resistance
As with the coracobrachialis, this muscle is not
very powerful on its own.

28. Shoulder Joint Muscles
Latissimus dorsi – latissimus means widest &
dorsi means back (Latin). Powerful in adduction, extension and internal rotation of humerus.
Powerful contraction in chinning. Assisted in all
actions by teres major.
What are the actions of the latissimus dorsi?
Adduction
Internal Rotation
Extension
Horizontal abduction

29. Latissimus Dorsi

30. Shoulder Joint Muscles
What are some activities involving or strengthening the Latissimus dorsi?
Lat pull downs Chinning Rope climbing
Dips Rowing Pull over

31. Pectoralis Major

32. Shoulder Joint Muscles
Pectoralis Major (pectus, breast bone) –
works closely with anterior deltoid.
It is divided into upper and lower sections.
Actions of Pectoralis Major
Upper fibers (clavicular head): internal rotation,
horizontal adduction, some flexion, some abduction
Lower fibers (sternal head): internal rotation,
horizontal adduction, extension, some adduction

33. Shoulder Joint Muscles
Exercises or activities involving the pectoralis
major?
Bench press Push ups Dumbell flies
Pull ups Incline press Decline press
Incline press muscles combine bench & overhead presses.
Decline press made up of bench press & the dip.

34. Shoulder Joint Muscles
Biceps brachii (short and long heads) originate on the scapula and insert on the radius. It crosses two joints. Short head assists flexion, adduction; Long assists with abduction.
Triceps brachii (long head) originates on the scapula just below the glenoid fossa. It assists with shoulder extension and adduction.

35. Shoulder Joint Injuries
Dislocation: the head of the humerus is pushed out of the glenoid fossa. The glenohumeral joint is the most commonly dislocated joint in the body.
Rotator cuff damage: this is the most common disorder of the shoulder. Supra-spinatus is most commonly injured.

36. Shoulder Joint Injuries
Rotational injuries: tears of the labrum, the rotator cuff muscles, and the biceps brachii tendon among injuries resulting from repeated, forceful rotation at shoulder. Tears of rotator cuff attributed to extreme tension during deceleration phase of throwlike motion.
Subscapular neuropathy: compression of subscapular nerve.