Upper Trapezius Muscle
O: Occipital bone, nuchal ligament on upper cervical spinous processes
I: Outer third of clavicle, acromion process
A: Scapular elevation and upward rotation
N: Spinal accessory (cranial nerve XI), C3 and C4 sensory component
Middle Trapezius Muscle
O: Spinous processes of C7-T3
I: Scapular spine
A: Scapular retraction
N: Spinal accessory (cranial nerve XI), C3 and C4 sensory component
Lower Trapezius Muscle
O: Spinous processes of middle and lower thoracic vertebrae
I: Base of the scapular spine
A: Scapular depression and upward rotation
N: Spinal accessory (cranial nerve XI), C3 and C4 sensory component
Levator Scapula Muscle
O: Transverse processes of first 4 cervical vertebrae
I: Vertebral border of scapula between the superior angle and spine
A: Scapular elevation and downward rotation
N: Third and fourth cervical nerves and dorsal scapular nerve (C5)
Rhomboid Muscles
O: Spinous processes of C7-T5
I: Vertebral border of scapula between the spine and inferior angle
A: Scapular retraction, elevation, and downward rotation
N: Dorsal scapular nerve (C5)
Serratus Anterior Muscle
O: Lateral surface of the upper 8 ribs
I: Vertebral border of the scapula, anterior surface
A: Scapular protraction and upward rotation
N: Long thoracic nerve (C5, C6, C7)
Pectoralis Minor Muscle
O: Anterior surface, 3rd-5th ribs
I: Coracoid process of the scapula
A: Scapular depression, protraction, downward rotation, and tilt
N: Medial pectoral nerve (C8, T1)