The most important function of the back and neck is to support our heads in the upright posture typical and unique to human beings. The adult head weighs 12 to 16 pounds and must be balanced on the spinal column. The head must be stabilized so it does not wobble each and every time we swallow.
In good posture the ears are in a vertical line over the shoulders, hips, knees and ankles. In kids, the head is heavier relative to the body than it is in an adult so the head balancing act is more problematic.
Human beings are obligate nasal breathers. Breathing is a primal function. We must be able to breathe to survive. The mouth is merely a back-up breathing organ. When the nasal airway is patent, normal resting or sleeping posture is with the lips together, teeth slightly apart, and the tongue in the roof of the mouth.
When nasal breathing becomes obstructed, the lips part, the jaws separate more to open the oral airway, and the tongue position shifts to the floor of the mouth to create a patent posterior oral airway. These changes cause adaptations of the head on the spinal column to a forward posture. The back and neck adapt to keep the head over the feet.
Unilateral nasal obstruction in a nose with septal deviation causes unilateral changes such as higher ear, higher shoulder, and higher hip.
Proper nasal breathing is essential for good body posture. Early orthodontics in conjunction with appropriate pediatric care results in restoration of nasal breathing and a catch up growth spurt that results in normal posture by the time all the permanent teeth are in the mouth.