Characteristic of facial muscle and efferent nerve on physiology and anatomy.

OBJECTIVE: To study the specialty of orbicularis oculi muscles, nerves and oris muscles, nerves and mechanism of difference of facial muscular injury in facial paralysis deeply. METHODS: The conductive velocity of the efferent nerves of orbicularis oculi and oris muscles of the health human beings and guinea pigs is measured with electromyogram (EMG) apparatus. RESULTS: The conductive velocity of orbicularis oculi nerve is quicker and oris muscles are controlled by facial nerves on both sides. Measuring the threshold of Strength-Duration (S-D) curves of the motor point of orbicularis oculi and oris muscles shows the threshold of the former is lower. Measuring the diameter of orbicularis oculi and oris nerve fibers on the guinea pigs and rabbits shows the diameter of orbicularis oculi nerve fiber is bigger. The area of secondary synapse space of orbicularis oculi motor end plate is larger than that of oris under scanning electron microscope. CONCLUSIONS: Orbicularis oculi muscles, orbicularis oculi nerves and oris muscles, oris nerves all have their own characteristic on physiology and anatomy. It elucidated the mechanism that orbicularis oculi muscle is easy to be injured.