A myographic measurement apparatus for direct strength measurement of the orofacial muscles, in particular, the lip and tongue muscles. The apparatus includes a pressure-sensitive probe that is adapted to be placed in engagement with the orofacial muscle being tested. The probe provides a pressure response representative of the muscle strength under test. The probe is coupled to a transducer that converts the probe's pressure response in real time to an electrical signal representative of the force exerted on the probe by the muscle under test. The probe provides a representative pressure reading continuously over a test run of prescribed duration. The electrical signal generated in the test run is sampled and analyzed in real-time to determine a characteristic maximum pressure and hence characteristic maximum muscle strength achieved over the test run. The maximum muscle strength is provided in a form that may be incorporated directly into computerized patient records. The pressure-sensitive probe is provided by a balloon probe that is pneumatically coupled to a transducer. A strength measurement is made by holding the balloon probe against the muscle to be tested and having the patient press against the balloon probe with that muscle. To assist in holding the balloon probe in position a support fixture is provided that includes an anchor member that the patient retains in the mouth, typically gripped by the teeth, and a retaining member that is fixed to the anchor member and is shaped to retain the balloon probe in position against the lip muscle under test. Two illustrative shapes of support fixtures are illustrated for making measurements of the front upper and lower lip muscles and of lateral lip muscle thrust.