Latissimus dorsi

action: adducts, extends and internally rotates arm

Trapezius

Action: rotation, retraction, elevation and depression of scapula

Rhomboid major

actions: retracts the scapula and rotates it to depress the glenoid cavity; fixes scapula to the thoracic wall

Rhomboid minor

Actions: retracts and rotates scapula, fixes scapula to thoracic wall

Teres major

actions: internal rotation (medial rotation) of the humerus

Teres minor

actions: laterally rotates the arm, adducts the forearm, stabilizes the humerus

Supraspinatus

actions: abduction of arm and stabilizes humerus

Infraspinatus

actions: lateral rotation of arm and stabilizes humerus

Subscapularis

actions: internally (medially) rotates humerus; stabilizes shoulder

Levator scapulae

actions: elevates scapula and tilts its glenoid cavity inferiorly by rotating scapula

Splenius

actions: extend, rotate, and laterally flex the head

Semispinalis

actions: extend the head

Serratus posterior superior

actions: elevate the ribs to aid in inspiration

Serratus posterior inferior

actions: depress the lower ribs to aid in expiration

Longissimus dorsi

actions:

Iliocostalis

actions:

Laterally: Flex the head and neck to the same side. Bilaterally: Extend the vertebral column.