Oi Nelson, Pandy Marcus G, Myers Barry S, Nightingale Roger W, Chancey Valeta Carol
Department of Biomedical Engineering, University of Texas at Austin.
Stapp Car Crash J. 2004 Nov;48:397-417. doi: 10.4271/2004-22-0017.
The aim of this study was to describe and explain the variation of neck muscle strength along the cervical spine. A three-dimensional model of the head-neck complex was developed to test the hypothesis that the moment-generating capacity of the neck musculature is lower in the upper cervical spine than in the lower cervical spine. The model calculations suggest that the neck muscles can protect the lower cervical spine from injury during extension and lateral bending. The maximum flexor moment developed in the lower cervical spine was 2 times higher than that developed in the upper spine. The model also predicted that the neck musculature is 30% stronger in the lower cervical spine during lateral bending. Peak compressive forces (up to 3 times body weight) were higher in the lower cervical spine. These results are consistent with the clinical finding that extension loading of the neck often leads to injuries in the upper cervical spine. Analysis of the model results showed that neck flexor strength was greater in the lower cervical spine because of the relatively large size of the sternocleidomastoid muscle. The hyoid muscles developed significant flexor moments about the joints of the upper cervical spine, as these muscles had relatively large flexor moment arms; however, this effect was offset by the action of the sternocleidomastoid, which exerted a large extensor moment in the upper spine. Lateral bending strength of the neck muscles was governed by geometry (i.e., moment arms) rather than by muscle size.
本研究的目的是描述和解释颈部肌肉力量沿颈椎的变化情况。建立了头颈部复合体的三维模型，以检验关于颈部肌肉在上颈椎产生力矩的能力低于下颈椎这一假设。模型计算表明，颈部肌肉在伸展和侧屈时可保护下颈椎免受损伤。下颈椎产生的最大屈肌力矩比上颈椎高2倍。该模型还预测，在侧屈时颈部肌肉在下颈椎的力量比上颈椎强30%。下颈椎的峰值压缩力（高达体重的3倍）更高。这些结果与颈部伸展负荷常导致上颈椎损伤的临床发现一致。对模型结果的分析表明，由于胸锁乳突肌相对较大，下颈椎的颈部屈肌力量更大。舌骨肌在上颈椎关节处产生显著的屈肌力矩，因为这些肌肉具有相对较大的屈肌力矩臂；然而，这种作用被胸锁乳突肌的作用抵消，胸锁乳突肌在上颈椎施加了较大的伸肌力矩。颈部肌肉的侧屈力量由几何结构（即力矩臂）而非肌肉大小决定。
