Scapulothoracic Joint

Pseudo-Joint of the shoulder girdle

Authors
Affiliations

Nate Yomogida, B.S., SPT

Doctor of Physical Therapy

B.S. in Kinesiology

Chloë Kerstein, B.S., SPT

Doctor of Physical Therapy

B.A. in Neuroscience

There are 6 primary movements of the scapulothoracic joint:

  1. Elevation and Depression
  2. Protraction and Retraction
  3. Upward and Downward rotation

Alignment

  • Vertebral border
    • Parallel to spine, 2-3 finger width (3’’) from the midline of the thorax
  • Between 2nd and 7th thoracic vertebrae
  • 30° ant to the frontal plane (scapular plane)
  • 10° ant tilt
  • 5-10° upward rotation

Elevation & Depression

Elevation

Elevation refers to when the scapula slides superiorly relative to the thorax. Shrugging the shoulders is an example of scapular elevation.

The scapulothoracic joint as 40° of elevation.

  • Includes elevation of clavicle at SC and downward rot of scap at AC

Elevation is created by coactivation of the upward rotators along with the levator scapulae. The activation of the upward rotators brings the acromion (lateral) aspect of the scapula superomedially, but the levator scapulae counteracts the rotation to create pure scapular elevation.

Depression

Depression of the scapulothoracic joint refers to when the scapula slides inferiorly relative to the thorax from an elevated position.

The scapulothoracic joint is capable of 10° of depression.

Protraction & Retraction

Protraction

Protraction refers to when the medial border of the scapula slides anterolaterally relative to the thorax. This will result in movement of the medial border away from the spine. An example of protraction is when you are reaching forward as far as possible.

The scapulothoracic joint is capable of 20° of protraction.

Protraction requires a combination of the serratus anterior and pec minor.

Retraction

Scapular retraction refers to when the medial border of the scapula slides posteromedially relative to the thorax towards the midline. This is exemplified when you “pinch” the shoulder blades together.

The scapulothoracic joint is capable of 15° of retraction.

Retraction is produced through contraction of middle trap and lower trap with assistance of rhomboid major and minor.

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Upward & Downward rotation

Upward and downward rotation of the scapula refers to scapular movement in the frontal plane.

Upward Rotation

During scapular upward rotation, the inferior angle of the scapula rotates superiolaterally relative to the thorax This results in the glenoid fossa facing upwards.

Upward rotation is a key component when raising the arm upward.

The scapulothoracic joint is capable of 60° of upward rotation.

Downward rotation

Downward rotation refers to when the inferior angle of the scapula rotates in an inferomedially direction. Downward rotation is most obvious when lowering the scapula from an upwardly rotated position.

The scapulothoracic joint is capable of 30° of downward rotation.

Downward rotation is key component of lowering the arm down to one’s side.

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Muscles

As a rule of thumb, all muscles that attach on the scapula contribute to its mobility.

Table 5: Scapulothoracic muscles
Muscle Origin Insertion Innervation Action
Note

Although the subclavius does not directly insert on the scapula, it indirectly depresses the shoulder girdle by depressing the clavicle.

Anterior & Posterior Tilting

Anterior Tilt

Posterior Tilt

20° post tilt during arm elevation

Kinematics

Force couple

  • Serratus anterior (greatest mechanical advantage for UR)
  • Upper trap (Initiation and throughout)
  • Late phase: Lower trap

Internal Rotation

<= 5° IR/ER

External Rotation

<= 5°

Stabilization

The Serratus Anterior (along with the rhomboids) serves to aid in scapular stability during arm elevation

Superior View of the shoulder: You can see how the rhomboids and SA both actively stabilize the scapulothoracic joint by pulling the scapula towards the thoracic wall3

Superior View of the shoulder: You can see how the rhomboids and SA both actively stabilize the scapulothoracic joint by pulling the scapula towards the thoracic wall

Stabilization

  • Middle trap (add / retract) which counteract the protraction force of the Serratus anterior, resulting in stabilization of the scapula

Dysfunction

  • Scapular winging

References

1.
Neumann DA, Kelly ER, Kiefer CL, Martens K, Grosz CM. Kinesiology of the Musculoskeletal System: Foundations for Rehabilitation. 3rd ed. Elsevier; 2017.
2.
Jones B. B Project Foundations. b Project; 2025.
3.
Dutton M. Dutton’s Orthopaedic Examination, Evaluation, and Intervention. 5th ed. McGraw Hill Education; 2020.

Citation

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