Vestibular influences on cat lumbar paravertebral muscles.

Recordings were made from nerves innervating ventral lumbar paravertebral muscles (quadratus lumborum) during natural vestibular stimulation in vertical planes. The best direction of vestibular stimulation for producing an increase in nerve activity was near nose-up pitch in two-thirds of the animals, but was near nose-down pitch in the others. The response gain (re. position) was flat across the frequency range of 0.05-1 Hz, and the responses persisted throughout 11-s static tilts. These data suggest that otolith organs activated by pitch influence activity in the lumbar paravertebral muscles. These responses may serve to stabilize the vertebral column during movements involving body pitch, such as vertical climbing.