Jaw abnormality sagittally divides the face into five equal parts: It is insufficient to derive at a diagnosis of jaw deformity solely based on the clinical examination. Hence, additional information is gathered from diagnostic tests, which may include dental model analyses and radiographic imaging studies. Mandibular micrognathia is the condition when lower jaw is smaller than normal. Failure of the ramus to develop will give rise to micrognathia.<ref name="Elsevier/Churchill Livingstone"></ref> Micrognathia can be classified as either congenital or acquired. Clinical appearance of some patients with congenital type of mandibular micrognathia can have a severe retrusion of the chin but by actual measurements,
Jaw coupling in compression. The elastomer of the spider can be made in different materials and hardness, which allows the user to customize the coupling to best serve their application. Considerations for elastomer selection include ability to dampen vibration, ability to handle misalignment, operational temperature range, speed of equipment, and chemical conditions. Jaw couplings are considered "fail-safe" because, should the elastomer fail or wear away, the jaw coupling hub teeth will mate, much like teeth on two gears, and continue to transmit torque. This may or may not be desirable to the user depending on the application. Jaw couplings elastomers are wearing