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