Manual Muscle Testing: Shoulder Flexion

Original Editor - Claire Knott

Top Contributors - Hollie Webb, Madison Gore, Claire Knott, Kaley Golden, Wanda van Niekerk, Kim Jackson, Joao Costa, Nikhil Benhur Abburi and Tony Varela  

Updated: April 8th, 2024. Editors: Student doctors of Physical Therapy: Hollie Webb, Kaley Golden, and Madison Gore.

Welcome to Arkansas Colleges of Health Education School of Physical Therapy Musculoskeletal 1 Project. This space was created by and for the students at Arkansas Colleges of Health Education School in the United States. Please do not edit unless you are involved in this project, but please come back in the near future to check out new information!!

Introduction

Manual Muscle Tests (MMT) represent an imperative form of assessing muscle/tendon strength (or lack there of). The numerical grades, provided by the examiner, demonstrate a consistent form of documentation. Assessing the patients response to intervention requires regular testing and documentation throughout the rehabilitation process. Upon evaluation, performing MMT’s will provide a baseline measurement that the examiner can refer back to if needed.

Performing a MMT requires positioning specific to the muscle actions. Because of this specificity, the examiner can determine the muscle responsible for the movement deficit. Based on the MMT grade, the examiner can assign appropriate interventions to combat the deficiency in strength.

Muscles involved in Shoulder Flexion:

• Coracobrachialis
• Anterior Deltoid
• Biceps brachii

Shoulder Flexion Biomechanics:

Osteokinematics:

Shoulder flexion occurs in the sagittal plane, with a normal range of motion (ROM) of: 0-180°. The glenohumeral joint, of the shoulder girdle, is associated with shoulder flexion osteokinematics. The glenohumeral joint is seated between the glenoid fossa and the humeral head.

Arthrokinematics:

Concisely, shoulder flexion occurs with the convexity (humeral head) moving on a concavity (glenoid fossa). This means, in order for the shoulder to flex, the humeral head has to posteriorly roll on a fixed glenoid fossa. With this posterior roll, an inferior glide simultaneously occurs (for the first 60°).

The coracobrachialis muscle initiates the posterior roll of the humeral head on the glenoid fossa. From this initiation, the coracobrachialis, anterior deltoid, and biceps brachii continue to promote the posterior roll until the end-of-range.

Initiation of shoulder flexion also involves an inferior glide of the humeral head on the glenoid fossa. At approximately 60° of shoulder flexion, this inferior glide ceases and the humeral head remains secure in the glenoid fossa.

Shoulder flexor muscles must concentrically contract, in collaboration with other shoulder girdle muscles , to achieve full ROM.

For more information about shoulder osteokinematics and arthrokinematics, click here.

Purpose:

MMT grades are given subjectively by the examiner based on the patient’s strength. Examiners assign numerical grades, used to represent the patient’s ability/inability to: (1) resist the external pressure (fair 3+ and higher); (2) actively resist the force of gravity (fair 3); or, (3) move through range of motion (fair 3- and lower). These numerical grades represent a consistent form of measurement that indicates whether the patient progresses, regresses, or remains the same.

Break Test:

If the patient can actively hold against gravity, the examiner will gradually apply pressure perpendicular to the testing position. The muscle is considered breakable if the patient cannot maintain original testing position, or if they begin to show any adverse signs/symptoms to the applied pressure. Ideally, the examiner does not want to break the patient out of testing position. If the examiner is unable to break the patient, the muscle strength is considered normal (5/5).

Grading:

Normal (5): Able to hold test position and resist strong pressure; examiner is unable to "break" the test position; > 95% effort from examiner.

Good (4+): Able to hold test position and resist moderate to strong pressure before muscle failure; 75-95% effort from examiner.

Good (4): Able to hold test position and resist moderate pressure before muscle failure; 50-74% effort from examiner.

Good (4-): Able to hold against gravity and resist slight to moderate pressure before muscle failure; 25-49% effort from examiner.

Fair (3+): Able to hold against gravity and resist minimal pressure before muscle failure; 1-24% effort from examiner.

Fair (3): Able to hold against gravity; no additional force applied.

Fair (3-): Unable to hold agaisnt gravity; patient gradually falls from test position.

Poor (2+): Unable to hold against gravity; achieves only partial ROM against gravity; in a *gravity eliminated (GE) position, able to move through full ROM with resistance at end-range only.

Poor (2): Unable to hold against gravity; able to move through full ROM in a GE position.

Poor (2-): Unable to hold agasint gravity; able to move through partial range in a GE position.

Trace (1): No visible osteokinematic movement; examiner is able to palpate a contraction of the muscle/tendon.

Zero (0): No visible osteokinematic movement or palpable contraction of muscle/tendon.

*Gravity Eliminated (GE): patient positioned in a way that does not require muscle contraction against the force of gravity. This position typically occurs in the horizontal plane.

Coracobrachialis:

Actions: The Coracobrachialis muscle concentrically contracts to perform shoulder flexion and abduction.

Innervation: Musculocutaneous n.

Weakness signs: Weakness can be observed with the synchronous movement of shoulder flexion, full elbow flexion, and full forearm supination.

Patient Position:

• Sitting or Supine

Therapist Position:

• Standing on ipsilateral side of the shoulder being tested

Stabilizing hand: No stabilization is necessary if the trunk is stable. However, if the trunk’s original testing position is not maintained, stabilize the contralateral shoulder.

Movement hand: Distal anteromedial surface of the humerus.

Direction of force: Perpendicular to the muscle actions. A sweeping (diagonal) motion through shoulder extension and adduction.

How to perform the MMT:

• The examiner asks the patient to assume a *hook-lying position on the table.
• The examiner passively moves the affected shoulder into flexion and slight external rotation; the elbow into full flexion; and, the forearm into full supination (Positioning this way will decrease the assistance of the biceps brachii).
• The examiner then asks the patient to perform the actions without assistance, to ensure their achievement of full ROM.
• If no pain is present, the examiner resets the patient to starting test position and applies gradual resistance against the anteromedial surface of the distal humerus, in the direction of shoulder extension and slight abduction.
• The patient does his/her best to resist the external force of shoulder flexion and adduction (muscle actions).
• Gradual pressure is continued until there is a “break” of position or the examiner determines the test is complete.

*Hook-lying: Patient is lying supine on the table with the knees in a flexed position.

Anterior Deltoid:

Actions: The anterior fibers of the deltoid muscle concentrically contract to flex and internally rotate the shoulder.

Innervation: Axillary n.

Weakness signs: The anterior deltoid fibers can be considered weak if the patient has difficulty with shoulder flexion and internal rotation. However, to isolate anterior deltoid weakness, other MMT’s need to be performed.

Patient Position:

• Seated with their feet flat on the ground.

Therapist Position:

• Therapist stands behind the patient. **mirror placed in front of patient in order to observe reactions**

Stabilizing hand: Superior and posterior surface of the shoulder/scapula.

Manipulating hand: Distal anteromedial surface of the humerus.

Direction of Force: Perpendicular to the muscle actions in the direction of shoulder extension.

How to perform the MMT:

• Patient is seated with their feet maintained on the floor.
• Examiner passively places the shoulder in starting position: approximately 80 degrees of abduction, slight flexion, and slight lateral rotation. The examiner then passively moves the patient through the actions of the muscle.
• To ensure the patient has appropriate ROM, he/she is asked to actively perform the motion.
• If no pain is present with active ROM, the stabilizing and manipulating hands are placed. The patient is asked to hold that position and resist the external force.
• The examiner gradually applies perpendicular force to the patients position by pulling them into shoulder extension and adduction.
• Gradual pressure is continued until there is a “break” of position or the examiner determines the test is complete.

Biceps Brachii:

Actions: The bicep muscle has two heads, long and short. The short head of the bicep brachii aids in shoulder abduction. The long head of the bicep brachii assists with shoulder flexion and abduction. Together at their insertion, the short and long head of the biceps brachii flex and supinate the elbow.

Innervation: Musculocutaneous n.

Weakness signs: Weakness of the bicep brachii muscle is evident if the patient is unable to flex his/her elbow. This will likely be their main concern because this will greatly impact their daily activities.

Patient Position:

• Supine; hook-lying position.

Therapist Position

• Standing on ipsilateral side of arm being tested

Stabilization hand: Distal posterior humerus, just proximal to olecranon (Use a towel to ensure loose packed position).

Manipulating hand: Distal palmer (anterior) surface of the forearm, just proximal to the wrist joint line.

Direction of Force: Perpendicular to the muscle actions in the direction of elbow extension.

How to perform the MMT:

• Patient assumes a hook-lying position, on the table, with a towel beneath the distal posterior humerus.
• Examiner then passively moves the patient through elbow flexion and extension, while maintaining full forearm supination.
• The patient is then asked to repeat the movement to ensure active ROM.
• If no pain is present, the patient is returned to the starting test position while placing the stabilizing and manipulating hands.
• Patient is then asked to maintain their position, and resist the external force being applied.
• Examiner applies gradual force, pulling the patient into elbow extension.
• Gradual pressure is continued until there is a “break” of position or the examiner determines the test is complete.