(A) Trapezius:-

Origin – Medial one-third of the superior nuchal line, Ligamentum nuchae and C7-T12 spines.                     

Insertion – Lateral one-third of clavicle, acromion and spine of the scapula.

Nerve Supply – Spinal root of accessory Nerve and Cervical Nerves. 

Action – Elevate and Retract Scapula, Extension and Side flexion of the axial skeleton.

(B) Latissimus dorsi:-

Origin – Posterior one-third of the outer lip of iliac crest, Spines of T7-T12, Inferior angle of the scapula. 

Insertion – Intertubercular sulcus of the humerus, between the pectoralis major and teres major muscles. 

Nerve Supply – Thoracodorsal Nerve. 

Action – Adduction, Extension and Medial rotation of the shoulder, Assists in Respiration

(C) Levator scapulae:-

Origin – Transverse process of C1 and C2, Posterior tubercles of the transverse processes of C3 and C4. 

Insertion – Superior angle and medial border of the scapula.

Nerve Supply – Dorsal scapular Nerve.

Action – Lateral flexion and Extension of Neck, Elevation of the scapula.

(D) Rhomboid minor:-

Origin – Lower part of ligamentum nuchae and Spines of C7 and T1. 

Insertion – Base of the triangular area at the root of the spine of the scapula. 

Nerve Supply – Dorsal scapular Nerve (C5).

Action – Retraction of scapula.

(E) Rhomboid major:-

Origin –  Spines of  T2 – T5 and Supraspinous ligaments. 

Insertion – Medial border of scapula below the root of the spine of the scapula. 

Nerve Supply – Dorsal scapular Nerve (C5).

Action – Retraction of scapula.