The scapula plays a very important role in shoulder function and efficient movement.

The main stabiliser:

  • levator scapulae
  • trapezius
  • serratus anterior
  • rhomboideii

of the scapula must dynamically position the glenoid, so that efficient glenohumeral movement can occur.

When dysfunction is present in the scapular musculature, shoulder function is inefficient, and in further consequence the subacromial space is decreased, which is called “shoulder impingement”.

That can result not only in decreased performance but also may predispose to shoulder injury.

M. levator scapulae, mm. rhomboideii                       M. trapezius                                       M. serratus anterior (Platzer)

 

M. levator scapulae

Origin: Tubercula posterior of the Processus transversus C1-4

Insertion: Angulus superior scapulae and margo medialis

Innervation: N. dorsalis (C4-5)

Action: Elevation of the scapula and rotation of the angulus inferior to medial

Mm. rhomboideii

rhomboideus major (4)

Origin: Processi spinosi T1-4
Insertion: Margo medialis scapulae
Innervation: N. dorsalis scapulae (C4-5)
Action: Adduction and downward rotation of the scapula

rhomboideus minor (1)

Origin: Processi spinose C6 and C7
Insertion: Margo medialis scapulae
Innervation: N. dorsalis scapulae (C4-5)
Action: Adduction and downward rotation of the scapula

M. trapezius

The trapezius muscle is divided into three areas: Pars descendens (2) or upper fibres, Pars transversa (3) or middle fibres, Pars ascendens (4) or lower fibres.

Innervation: N. accessorius and ramus trapezius (C2-4)

Action: Stabilises the scapula and draws it towards the spine. Pars descendens supports minimal the elevation.

Pars descendens:
Origin: Linea nuchalis superior, Protuberantia occipitalis  externa and Lig.nuchae Insertion: Lateral part of the clavicula

Pars transversa:
Origin: Processi spinosi and Ligg. supraspinalia of C7-T3
Insertion: Acromial end of the clavicula, acromion, and a part of the spina scapulae

Pars ascendens:
Origin: Processi spinosi and Ligg. supraspinalia of T3-T12
Insertion: Trigonum spinae and spina scapulae

M. serratus anterior

(Hambley 2013)

Origin: Anterolateral surface of first 8 or 9 ribs

Insertion: Margo medialis of the scapula between angulus superior and angulus inferior scapulae

Innervation: N. thoracicus longus (C5-7)

Action: Stabilises the scapula and pulls it to the rib cage. The muscle serratus anterior is an antagonist to the muscle rhomboideus.

 

Reference:

[1] Hambly A. (2013). Shoulder Pain. Retrieved from http://www.whitetigernaturalmedicine.com/craniosacral-therapy/craniosacral-therapy-upper-shoulder-pain

[2] Platzer W. (1999). Taschenatlas der Anatomie in 3 Bänden, 1 Bewegungsapparat. Stuttgart, Georg Thieme Verlag. (7. vollständig überarbeitete Auflage)