ABSTRACT
The functional significance of proprioceptors in the intercostal muscles and diaphragm has been a topic of intense research and debate for more than 40 years. Much is known concerning the distribution, projection pathways, transduction properties, and reflexes associated with intercostal muscle afferents. Compared with intercostal afferents, relatively little is known about proprioceptors in the diaphragm. Review articles concerning the innervation of chest wall muscles reflect this lack of information on the role of diaphragmatic proprioceptors in the control of breathing (Sant'Ambrogio and Remmers, 1985; Shannon, 1986). Only within the past few years has it been recognized that chest wall proprioceptors may provide sensations important in adjusting respiratory motor drive in the face of added loads to breathing. Evidence is also emerging that inspiratory muscle afferents are activiated by inspiratory loads and reach the somatosensory cortex in conscious human subjects (Road, 1991 ; Frazier and Revelette, 1991).
