Muscle Test: Deltoid

Test, Exam and Sign Description

Muscle Testing: Deltoid

Origin: Anterior fibers:

Clavicle (shaft: anterior border and superior suface of lateral 1/2)

Middle fibers:

Scapula (acromion, lateral margin and superior surface)

Posterior fibers:

Scapula (spine on lower lip of posterior border)

Insertion: Humerus (deltoid tuberosity on lateral mid-shaft via humeral tendon)

Innervation: Cervical root(s): C5 and C6

Nerve: axillary nerve (ventral rami)

Grading of muscle strength:

Grade	Strength	Description
5*	Normal	Completes full range of motion against maximal finger resistance
4*	Good	Tolerates moderate resistance
3	Fair	Completes full range of motion with no resistance
2	Poor	Completes partial range of motion
1	Trace	Slight contractile activity
0	Zero	No contractile activity
*The distinction between Grades 4 and 5 is based on comparison with the normal hand and, barring that, extensive experience in testing the hand.

Testing

Anterior deltoid (shoulder flexion)
Position of patient	Short sitting with arms at sides, elbow slightly flexed, and forearm pronated
Examiner’s actions	Stands at test side; hand applying resistance is contoured over the distal Humerus just above the elbow; the other hand may stabilize the shoulder
Instructions for the patient	“Raise your arm forward to shoulder height. Hold it. Don’t let me push it down.”
Posterior deltoid (shoulder extension)
Position of patient	Prone with arms at sides and shoulder internally rotated (palm up)
Examiner’s actions	Stands at test side; hand applying resistance is contoured over the posterior arm just above the elbow
Instructions for the patient	“Lift your arm as high as you can. Hold it. Don’t let me push it down.”

*Posterior deltoid (shoulder abduction, horizontal)*
Position of patient	Prone with shoulder abducted to 90° and forearm off the edge of the table with elbow straight
Examiner’s actions	Stands at test side; hand applying resistance is contoured over the posterior arm just above the elbow
Instructions for the patient	“Lift your elbow up toward the ceiling. Hold it. Don’t let me push it down.”
Middle deltoid (shoulder abduction)
Position of patient	Short sitting with arm at side and elbow slightly flexed
Examiner’s actions	Stands behind the patient; hand applying resistance is contoured over the arm just above the elbow
Instructions for the patient	“Lift your arm out to the side to shoulder level. Hold it. Don’t let me push it down.”

Presentation Photos and Related Diagrams

Deltoid muscle

Definition of Positive Result

In muscle testing, a normal result is a positive one. During a normal muscle test, the examiner should observe a normal muscle contraction that can move the joint or tendon against full resistance.

Definition of Negative Result

In muscle testing, an abnormal result is a negative one. During an abnormal muscle test, the examiner should observe an abnormal muscle contraction that can move the joint or tendon. In a complete denervation injury, such as a complete nerve laceration, there will be no evidence of any muscle function and the muscle testing grade will be 0.

Comments and Pearls

Do not allow shoulder elevation or lateral flexion of the trunk to the opposite side because these movements will create the illusion of shoulder abduction.
If the shoulder is painful in abduction, especially with lifting, resisted external rotation is a good substitute exercise
The deltoid is innervated by C5

Diagnoses Associated with Tests, Exams and Signs

CERVICAL RADICULOPATHY

References

1. Hislop JH, Avers D, Brown M. Daniels and Worthingham's Muscle Testing, Techniques of Manual Examination and Performance Testing. 9th ed. St. Louis, Missouri: Elsevier Saunders, 2014, pp. 138–202.