The prime functions of latissimus dorsi are:
- extension of the flexed arm at the glenohumeral joint
- adduction and medial rotation of the shoulder at the glenohumeral joint
Additionally, if the arm is fixed in abduction, it acts to:
- retract the pectoral girdle
- elevate the trunk and pelvis superiorly when the pectoral girdle also is fixed; the key function, in conjunction with pectoralis major is as a climbing muscle. The action on the pelvis is often used by patients with paralysis of the lower limbs to assist in the production of a modified gait. Fixing the arms allows latissimus dorsi to act also as an accessory muscle of respiration:
- by elevation of its costal origin, to facilitate deep inspiration
- be the compressive action of its lower fibres around the circumference of the lower thorax, to facilitate expiration