During a heavy exercise, energy requirement increases, causing insufficiency of inspiratory muscles to overcome the elastic recoil of the lungs. Respiratory accessory muscles are in charge during forced inspiration or expiration. Muscles elevating chest cage during respiration are referred to muscles of inspiration, while muscles depressing chest cage are termed as muscles of expiration. In case of high cervical spinal injury, sternocleidomastoid muscle remains intact and is the objective of physiotherapy. Expiratory muscle strength is significant in patients suffering chronic obstructive pulmonary disease. Involvement of bulbar muscles in patients with neuromuscular diseases presents a deterioration of the disease.