The muscles that produce phonation can also adduct the glottis and the false cords to provide an impenetrable barrier to foreign material.

Upper motor neurons in the reticulospinal tracts control muscles used for:

a. Posture and gait b. Precisely controlled movements c. Balance

As the body ages, the intervertebral discs:

A) calcify and become more rigid. B) enlarge and result in increased height. C) are not able to protect the spinal cord. D) lose water content and become thinner.