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-thrust maneuver tongue forward and prevents it from obstructing the entrance to the trachea. Traditionally, the jaw-thrust maneuver has been considered the better alternative (rather than the head-tilt/chin-lift maneuver) when a first aider suspects that the patient may have a spinal injury (especially one to the neck portion of the spine). The International Liaison Committee on Resuscitation has reviewed various studies that found no spine-protecting advantage to the jaw-thrust maneuver. Its "Treatment Recommendation" under "Opening the Airway" says, "Rescuers should open the airway using the head tilt–chin lift maneuver." If the patient is in danger of pulmonary aspiration, he or she should