by Dennis Zacharkow, PT
In 1846, Warren stressed that schoolchildren "should be frequently warned against the practice of maintaining the head and neck long in a stooping position." He emphasized the importance of proper desk height and inclination in counteracting this stooped position.
In her study of the postural responses of third grade children, Jones (1965) found that the greatest change in posture came with writing at a horizontal desk. The deterioration in posture was characterized by a marked forward and downward displacement of the head.
In a study involving ten healthy females (mean age 24 years), Harms-Ringdahl and Ekholm (1986) reported that sitting with the head and neck in a relaxed, forward-flexed position, a posture resulting in extreme flexion of the lower cervical and upper thoracic spine, resulted in the experience of pain or discomfort for all ten individuals within 15 minutes. The primary location of pain was the lower cervical and upper thoracic spinal region, although pain referred to the arm or head was also reported. During pain provocation, seven of the subjects reported experiencing one or more of the following vegetative sensations: sweating, nausea, tiredness, dizziness, general coldness or warmth.
With prolonged sitting at a horizontal desk, the slumped head posture, along with a slumped, round back posture, will easily become habitual. As a result, when the eyes are raised to look ahead, it has to be accomplished by an increased lordosis in the upper cervical spine. Eventually, "the back of the skull begins to be held contracted back into the upper neck in order to look straight ahead" (Barlow, 1980). A marked increase in neck muscle activity will be required to keep the head erect and the gaze horizontal (Jones et al., 1961; Gray et al., 1966; Bunch and Keagy, 1976).
The greater the slumped, kyphotic posture, the greater will be the forward thrust of the head, resulting in a marked increase in activity from the upper trapezius and other posterior neck musculature (Gray et al., 1966). A greater than 50 percent increase in muscle tension at the back of the neck has been reported when changing from an erect to a slumped sitting posture (Gray et al., 1966).
Alexander (1918) implicated the prolonged "crouching positions" at the school desk as contributing to the development of a defective kinaesthetic system, by altering the proper head-neck relationship. Head posture is considered critical in providing "the reference for the parts of the body in relation to one another and in relation to the surrounding space" (Laville, 1985).
Cohen's (1961) work showed that the neck proprioceptors are critical for orienting the head in relation to the body, and that neck proprioception "plays a very important role in maintaining proper orientation, balance and therefore motor coordination of the body."
According to Wyke (1972), the mechanoreceptors in the spine that primarily provide postural and kinaesthetic perception are more numerous in the apophyseal joints of the cervical region.
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