This document describes the muscles that contribute to various motions of the shoulder joint, including shoulder horizontal adduction, external rotation, internal rotation, and abduction to 90 degrees. For each motion, it lists the origin, insertion, action, and nerve supply of the main muscles involved. It also provides instructions for testing the strength of these muscles in normal, fair, and poor testing positions, including details on patient positioning, stabilization, palpation points, desired motion, and where to apply resistance.

1. Muscles contribute to
Shoulder Horizontal Adduction
Lower pectoralis major
• Origin:
• Anterior surface of costal cartilage of first six
ribs, adjacent portion of sternum
• Insertion:
• Intertubercle groove of humerus
• Action:
• Shoulder Horizontal Adduction
• Nerve supply:

2. Normal & Good
• Position:
• Supine with arm abducted to 90
degrees.
• Stabilization:
• Stabilize scapula to prevent abduction
of the scapula.
• Palpation:
• Below and near the origin at sternal
end of the clavicle.
• Desired Motion:
• Patient adducts arm through range of
motion.
• Resistance:
• Is given proximal to elbow joint.
Palpation

3. Fair
• Position:
• Supine with arm abducted to
90º.
• Stabilization:
• Stabilize scapula to prevent
abduction of the scapula.
• Palpation:
• Below and near the origin at
sternal end of the clavicle.
• Desired motion:
• Patient adducts arm to
vertical position.

4. Poor
• Position:
• Sitting with arm resting on
table in 90º of abduction.
• Stabilization:
• Stabilize trunk.
• Palpation:
• Below and near the origin at
sternal end of the clavicle.
• Desired motion:
• Patient brings arm forward
through ROM.

5. Trace & Zero
• Examiner palpates tendon of Pectoralis major near insertion
on anterior aspect of upper arm.
• Muscle fibers of both sternal and clavicular portions may be
observed and palpated on upper anterior aspect of thoracic.

6. Note
• Factor limiting Motion:
• Tension of shoulder extensor muscles
• Contact of arm with trunk.
• Fixation:
• In forceful horizontal adduction, contraction of
Obliquus externus abdominus muscle on same side.
• Substitution:
• 1-Anterior portion of deltoid
• 2-Coracobrachialis
• 3- Short Head of biceps.

7. Shoulder External Rotation
Teres Minor Infraspinatus

8. Muscles contribute to
Shoulder External Rotation
Teres Minor
• Origin:
• Posteriorly on upper & middle aspect
of lateral border of scapula
• Insertion:
• Posterior surface of greater tubercle of
the humerus
• Action:
Shoulder Extension
• Nerve supply:

9. Muscles contribute to
Shoulder External Rotation
Infraspinatus
• Origin:
• Posteriorly on upper & middle aspect of
lateral border of scapula
• Insertion:
• Posterior surface of greater tubercle of
the humerus
• Action:
Shoulder Extension
• Nerve supply:

10. Normal & Good
• Position:
• Prone with shoulder abducted to 90º,
upper arm supported on table and lower
arm hanging vertically over edge.
• Stabilization:
• Stabilize scapula with hand and
forearm, but allow freedom for rotation.
• Palpation point:
• None
• Desired motion:
• Patient swings lower arm forward and
up-ward and 'laterally rotates shoulder
through range of motion.
• Resistance:
• Is given above wrist on forearm.

11. Fair
• Position:
• Prone with shoulder abducted to 90º,
upper arm supported on table and lower
arm hanging vertically over edge.
• Stabilization:
• Stabilize scapula and place hand against
anterior surface of arm to prevent
abduction (without interfering with
motion).
• Palpation:
• None
• Desired motion:
• Patient swings lower arm forward and
up-ward and laterally rotates shoulder
through ROM.

12. Poor
• Position:
• Prone with entire arm over edge table
in medially rotated positron.
• Stabilization:
• Stabilize scapula.
• Palpation:
• None
• Desired Motion:
• Patient laterally rotates arm through
range of motion. (supination of the
forearm should not be allowed to
substitute for full range in lateral
rotation.)

13. Trace & Zero
• The Teres minor may be palpated on axillary
border of scapula, and Infraspinatus over body of
scapula below the spine.

14. Note
• Factors Limiting Motion:
• a- Tension of superior portion of scapular ligament.
• b- Tension of lateral rotator muscles of shoulder.
• Fixation:
• a- Weight of trunk.
• b- Contraction of Trapezius and Rhomboid major
and minor muscles to fix scapula
• Substitutions:
1. Wrist extensors
2. Roll the shoulder backwards.

15. Shoulder Internal Rotation
Subscapularis U. Pectoralis Major Latissimus DorsiL. Pectoralis Major

16. Muscles contribute to
Shoulder Internal Rotation
Subscapularis
• Origin:
• Anterior surface of subscapular
fossa
• Insertion:
• Lesser tubercle of the humerus
• Action:
• Shoulder Internal Rotation
• Nerve supply:

17. Muscles contribute to
Shoulder Internal Rotation
Upper pectoralis major
• Origin:
• Medial half of anterior surface of clavicle
• Insertion:
• Intertubercle groove of humerus
• Action:
• Shoulder Internal Rotation
• Nerve supply:

18. Muscles contribute to
Shoulder Internal Rotation
Lower pectoralis major
• Origin:
• Anterior surface of costal cartilage of first six
ribs, adjacent portion of sternum
• Insertion:
• Intertubercle groove of humerus
• Action:
• Shoulder Internal Rotation
• Nerve supply:

19. Muscles contribute to
Shoulder Internal Rotation
Latissimus dorsi
• Origin:
• a- Spines of lower 6 thoracic and lumbar vertebrae
• b- Posterior surface of sacrum& Posterior aspect of
crest of ileum
• c- Lower 3-4 ribs
• d- Inferior angle of scapula
• Insertion:
• Intertubercle groove of humerus
• Action:
• Shoulder Internal Rotation
• Nerve supply:

20. Normal & Good
• Position:
• Prone with shoulder abducted to 90 degrees,
upper arm supported on table and lower arm
hanging vertically over edge.
• Stabilization:
• Stabilize scapula with hand and forearm, but
allow freedom for rotation.
• Palpation:
• None
• Desired Motion:
• Patient swings lower arm backward and up-
ward and medially rotates shoulder through
range of motion.
• Resistance:
• Is proximal to wrist on forearm.

21. Fair
• Position:
• Prone with shoulder abducted to 90 degrees, upper arm
supported on table and lower arm hanging vertically over
edge.
• Stabilization:
• Stabilize scapula.
• Palpation:
• None
• Desired Motion:
• Patient swings lower arm backward and up-ward and
medially rotates shoulder through range of motion.

22. Poor
• Position:
• Prone with arm over edge of table in lateral rotation.
• Stabilization:
• Stabilize scapula.
• Palpation:
• None
• Desired Motion:
• Patient medially rotates arm through range of motion.
(Pronation of the forearm should not be
allowed to substitute for full range in medial
rotation.)

23. Trace & Zero
• Fibers of Subscapularis may be palpated deep in axilla
near insertion.

24. Shoulder Abduction to 90º
Middle Deltoid Supraspinatus

25. Muscles contribute to
Shoulder Abduction to 90º
Middle Deltoid
• Origin:
• Acromion process
• Insertion:
• Deltoid tuberosity on the lateral humerus
• Action:
• Shoulder Abduction to 90º
• Nerve supply:

26. Muscles contribute to
Shoulder Abduction to 90º
Supraspinatus
• Origin:
• Supraspinatus fossa
• Insertion:
• Greater tubercle of the humerus
• Action:
• Shoulder Abduction to 90º
• Nerve supply:

27. Note
• Factors Limiting Motion:
• None: range of motion incomplete.
• Fixation:
• Contraction of Trapezius and Serratus anterior
muscles.
• Serratus anterior and upper fibers of trapezius
assist in upward rotation of scapula as well as
in fixation.

28. Normal & Good
• Position:
• Sitting with arm at side in mid-position
between medial and lateral rotation.
• Elbow flexed a few decrees.
• Stabilization:
• Stabilize scapula.
• Palpation:
• Just below the acromion process of the
scapula.
• Desired Motion:
• Patient abducts the humerus to 90º(palm
down).
• Resistance :
• Is given proximal to elbow

29. Fair
• Position:
• Sitting with arm at side in midposition
between medial and lateral rotation.
• Elbow flexed a few degrees.
• Stabilization:
• Stabilize scapula.
• Palpation:
• Just below the acromion process.
• Desired Motion:
• Patient abducts arm to 90º (palm down).

30. Poor
• Position:
• Supine with arm at side in
midposition between medial and
lateral rotation.
• Elbow slightly flexed.
• Stabilization:
• Stabilize scapula over acromion.
• Desired Motion:
• Patient abducts arm to 90º
without Lateral rotation at
shoulder joint
Alternate