Muscles that make you shrug

What makes them exist?

The action of “shrugging” is highly discussed in many articles, blogs and youtube videos. Most of them agree on shoulder shrugging can lead to musculoskeletal pain and abnormal kinematics. In addition, “don’t shrug your shoulders” is something often said by doctors, physiotherapists and coaches, making their clients more aware of their postures.

With all the negative information on shrugging, do you ever wonder why these muscles ever exist?

Muscles for shoulder shrug

There are two major muscles responsible for this action:

Upper trapezius

The muscles originates from the occiput and inserts at the clavicle.

The figure shows the anatomy of the upper trapezius and levator scapulae.

By controlling the clavicle, the muscle has some access to the scapula movement, making the shoulder shrug.

This is a top-down view of the shoulder girdle. The black arrow represents a force by the upper trapezius making the scapula external rotate.

Levator scapulae

The muscle originates from the cervical spine and ends at the scapula superior angle.

This muscle has direct access to the elevation of the scapula (shoulder shrug). During muscle contraction, the scapula is elevated and downwardly rotated.

The arrows are the direction of scapula movement during contraction of levator scapulae.

Shrugging muscle roles

The muscles are responsible for….

1. letting the upper arm work against the gravity
   The muscles create an upward force to the shoulders, preventing any collapse during movement. Shoulder subluxation is often seen in hemiplegia patients, which the shrugging muscles are weak and atrophied.
2. placing the scapula and the shoulder joint in an optimal position
   The upper trapezius provides an upward force on the clavicle to keep the glenohumeral joint (the shoulder joint) in place.

The upper trapezius provide stability to the shoulder girdle. The shoulder will be maligned and unstable if the force is decreased.

Should we not shrug at all?

Before answering this question, you should know that shrugging happens in our everyday activities. For example:

1. Reaching a high object.
2. Aiming the hoops.
3. Carrying heavy objects.
4. Playing high fly with kids.
5. Carrying your drunk friend home.
6. Answering the phone between the shoulder and ear.

Shrugging is not a bad thing, in fact, it is there to help complete a task.

The take home message is: shrug whenever it is needed, be sure to relax when you are done. Those with shrugging compensations should seek help to correct their bad habits.

References：
Camargo PR, Neumann DA. Kinesiologic considerations for targeting activation of scapulothoracic muscles — part 2: trapezius. Braz J Phys Ther. 2019;23(6):467–75.

Neumann DA., Roen KE. Kinesiology of the Musculoskeletal System: Foundations for Rehabilitation 3rd edition.