Trapezius Muscle Test

Trapezius is a large trapezoid-shaped muscle on the posterior aspect of neck and trunk. The Trapezius Muscle Test is used to evaluate its strength and function.

How do you test the trapezius muscle?

The comprehensive trapezius assessment begins with the patient seated comfortably. The patient places their hands together over their head while the examiner stands behind them. The examiner then applies pressure by pushing the elbows forward. During normal function, all three parts of the trapezius contract simultaneously to stabilize the scapula against this force. This test provides an initial overview of general trapezius function before proceeding to more specific assessments of individual components.

See Also: Rotator Cuff of the Shoulder

Different part of the trapezius muscle can be tested separately as following:

To perform the upper trapezius muscle test: elevate the shoulder with the arm slightly abducted or simultaneously resist shoulder abduction and head side flexion. If the shoulder is elevated with the arm by the side, levator scapulae and rhomboids are more likely to be involved.

Middle trapezius can be tested with the patient in a prone position with the arm abducted to 90° and externally rotated. Then resistance is applied to horizontal extension of the arm, while watching for retraction of the scapula and feeling for the contractions. If scapular protraction occurs, the middle fibres of trapezius are weak.

To perform the lower trapezius muscle test, the patient again in prone lying position with arm abducted to 120° and the shoulder externally rotated. The examiner applies resistance to diagonal extension and watches for scapular retraction and feels for the contraction of the muscle fibers. If scapular protraction occurs, the lower trapezius is weak.

What is the result of Trapezius Weakness Test?

A positive trapezius weakness test manifests in several ways depending on which portion of the muscle is affected. When testing the complete trapezius, inability to maintain scapular position against resistance indicates generalized weakness.

In cases of trapezius paralysis, the scapula typically translates inferiorly, and the inferior angle rotates laterally. This creates a distinctive appearance of scapular winging and altered positioning at rest. Conversely, if the scapula appears elevated more than normal during assessment, this may indicate trapezius hypertonicity or cervical torticollis rather than weakness.

For segment-specific testing:

• Upper trapezius weakness presents as difficulty with shoulder elevation and reduced resistance to downward pressure on the shoulder.
• Middle trapezius weakness manifests as inability to retract the scapula during horizontal extension, with scapular protraction occurring instead.
• Lower trapezius weakness shows as failure to retract the scapula during diagonal extension, with protraction occurring during resistance.

Trapezius Weakness Test Reliability

Research on the reliability of trapezius weakness testing shows moderate to good reliability when performed by experienced clinicians. Inter-rater reliability is generally higher for testing of the upper trapezius compared to the middle and lower portions. Like many manual muscle tests, reliability increases with standardized positioning, clear instructions, and examiner experience.

Several factors can impact test reliability, including patient understanding and cooperation, examiner technique, and the presence of pain during testing. Pain inhibition may result in apparent weakness that does not reflect true neuromuscular dysfunction. Therefore, careful differentiation between pain-mediated and true neurological weakness is essential for accurate assessment.

To improve trapezius weakness test reliability, clinicians should ensure consistent patient positioning, standardized instruction, and controlled application of resistance. Correlation with other clinical findings, including posture assessment, movement analysis, and neurological examination, enhances diagnostic accuracy.

Clinical Applications

Trapezius weakness test is particularly valuable in several clinical scenarios, including evaluation of patients with suspected accessory nerve injury, cervical radiculopathy, thoracic outlet syndrome, and scapular dyskinesia. It also provides useful information when assessing occupational or sports-related shoulder complaints.

Following identification of trapezius weakness, treatment approaches may include targeted strengthening exercises, neurodynamic techniques, postural education, and activity modification. In cases of severe weakness due to nerve injury, referral for electrodiagnostic testing and potential surgical consultation may be warranted.

References

1. Kendall HO, Kendall FP. Muscles-testing and function. Baltimore: Williams & Wilkins; 1999.
2. Mercer S, Campbell AH: Motor innervation of the trapezius. J Man Manip Ther 8:18–20, 2000.
3. Haymaker W, Woodhall B: Peripheral Nerve Injuries. Principles of Diagnosis. London: WB Saunders, 1953.
4. Ourieff J, Scheckel B, Agarwal A. Anatomy, Back, Trapezius. [Updated 2021 Jul 26]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-. Available from: Pubmed
5. Sarvdeep S. Dhatt, Sharad Prabhakar – Handbook of Clinical Examination in Orthopedics. An Illustrated Guide-Springer Singapore.