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Scapulothoracic Joint

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Description

Movements of the scapulothoracic joint[1]
Anatomy of the scapulothoracic joint: scapula (s), ribs (r), subscapularis muscle (1), serratus anterior muscle (2), supraserratus bursa (*), infraserratus bursa (+).[2]
The four modeled degrees of freedom of the scapulothoracic joint.[3]
MRI Anatomy on a T1-weighted axial sequence: Scapula (S), ribs (dashed line), subscapularis muscle (solid line) and serratus anterior muscle (dotted line); an expected position of the supraserratus bursa (arrowhead), infraserratus bursa (arrow) are also indicated.[2]

Name

  • Scapulothoracic Joint
  • Scapulocostal joint
  • Scapulothoracic junction

General

  • Not a true anatomic joint, acts as a junction between anterior surface of scapula and thoracic cage
  • Supports other joints of the Shoulder Girdle
  • Function is to translate movement of the scapula against the thorax with movements of the upper limb

Gross Anatomy

  • No true bony attachment of the Scapula to the axial skeleton
  • No articular surfaces, ligaments or joint capsule are exist
  • Stability is provided by surrounding musculature[4]
  • Concavity of the scapula sits naturally on the convexity of the thoracic wall
  • Surfaces are separated by subscapularis, serratus anterior and the fascia between them

Articular Surfaces

  • Anterior surface of scapula
  • Superolateral surface of posterior thoracic wall

Scapular Stability

Muscles of the Scapulothoracic Joint

Biomechanics

  • Movements
    • Elevation (40°) - depression (10°)
    • Protraction (20°) - retraction (15°)
    • External rotation (60°) - internal rotation (30°)
  • Scapula resting position
    • Rotated anteriorly 30° relative to trunk
    • Tilted forward 20° in sagittal plane
  • Range of motion
  • Arm elevation: 30° glenohumeral joint, next 60° is combination of scapulothoracic and glenohumeral motion[5]

Scapulothoracic Bursa

  • Scapulothoracic bursa are neglected entirely or poorly understood in anatomy textbooks
  • Infraserratus bursa: between Serratus Anterior and chest wall
  • Supraserratus bursa: between Subscapularis and serratus anterior
  • Minor bursa inconsistently found at
    • Superomedial angle of scapula
    • Inferior angle of the scapula
    • Trapezoid bursa

Ligaments

Vascular Supply

  • Vascular supply comes from the surrounding muscles
  • Occipital, superficial cervical and dorsal scapular arteries (trapezius)
  • Thoracodorsal Artery (serratus anterior)
  • Dorsal scapular Artery, intercostal arteries (rhomboids)
  • Transverse cervical, ascending cervical (levator scapulae)

Innervation

Clinical Significance

See Also

References

  1. ↑ Image courtesy of orthobullets.com
  2. ↑ 2.0 2.1 Vidoni, A., et al. "Relevance of Scapulothoracic joint assessment for unknown shoulder pain." Indian J Musculoskelet Radiol 4 (2022): 61-69.
  3. ↑ Seth, Ajay, et al. "A biomechanical model of the scapulothoracic joint to accurately capture scapular kinematics during shoulder movements." PloS one 11.1 (2016): e0141028.
  4. ↑ Freedman L, Munro RH. Abduction of the arm in scapular plane: scapular and glenohumeral movements. J Bone Joint Surg Am. 1966;18:1503.
  5. ↑ Bergmann G. Biomechanics and pathomechanics of the shoulder joint with reference to prosthetic joint replacement. In: Kolbel R, Helbig B, Blauth W, editors. , eds. Shoulder Replacement. Berlin: Springer-Verlag; 1987:33-43
Created by:
John Kiel on 25 February 2020 18:21:02
Authors:
Last edited:
28 January 2026 15:10:57
Category:
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