颈膨大损伤是指颈部椎间盘突出或颈椎骨折导致的损伤。当发生这种损伤时，为什么下肢会出现硬瘫呢？下面我们来详细解释一下。

当颈膨大损伤发生时，首先会造成颈髓受压，进而影响到脊髓的正常功能。脊髓是连接大脑和身体各部分的重要通道，承载着传递运动、感觉和自主神经控制等功能。一旦脊髓受损，这些功能都会受到严重干扰。

英文翻译对照：

Cervical disc herniation refers to the damage caused by protrusion of the cervical intervertebral disc or fracture of the cervical vertebrae. When this type of injury occurs, why does lower limb paralysis occur? Let's explain it in detail below.

When a cervical disc herniation occurs, it first causes compression of the cervical cord, which in turn affects the normal function of the spinal cord. The spinal cord serves as an important pathway connecting the brain and various parts of the body, carrying functions such as motor and sensory transmission, as well as autonomic nervous control. Once the spinal cord is damaged, these functions are severely disrupted.

下肢硬瘫的原因之一是脊髓上行纤维受到损伤，导致了从大脑到下肢的运动信号无法顺利传输。脊髓上行纤维是负责传递大脑指令到下肢肌肉的神经纤维，一旦受损，就会阻断从大脑发送到下肢的运动指令，使下肢失去了运动功能。

英文翻译对照：

One of the reasons for lower limb paralysis is that the ascending fibers of the spinal cord are damaged, resulting in the inability of the motor signals from the brain to reach the lower limbs smoothly. The ascending fibers of the spinal cord are responsible for transmitting instructions from the brain to the muscles of the lower limbs. Once damaged, they block the transmission of motor commands from the brain to the lower limbs, causing the lower limbs to lose their ability to move.

另外，颈膨大损伤还会影响脊髓下行纤维的正常功能。脊髓下行纤维是负责传递感觉信号和自主神经控制的神经纤维。当脊髓受损时，下行纤维的传递也会受到干扰，导致下肢出现感觉异常和自主调节障碍。

英文翻译对照：

In addition, cervical disc herniation also affects the normal function of the descending fibers of the spinal cord. The descending fibers of the spinal cord are responsible for transmitting sensory signals and autonomic nervous control. When the spinal cord is damaged, the transmission of the descending fibers is also disrupted, resulting in abnormal sensations and impaired autonomic regulation in the lower limbs.

最后，颈膨大损伤可能导致脊髓的血液供应不足。脊髓是一个高度代谢的组织，需要充足的血液供应来提供氧气和营养物质。如果脊髓的血液供应受到阻碍，就会导致脊髓功能受损，进而引发下肢硬瘫。

英文翻译对照：

Finally, cervical disc herniation may lead to insufficient blood supply to the spinal cord. The spinal cord is a highly metabolically active tissue that requires an adequate blood supply to provide oxygen and nutrients. If the blood supply to the spinal cord is hindered, it can result in impaired spinal cord function and subsequently cause lower limb paralysis.

总结起来，颈膨大损伤导致下肢硬瘫的原因主要包括脊髓上行纤维和下行纤维功能的受损，以及脊髓血液供应的不足。了解这些原因有助于我们更好地理解颈膨大损伤对身体功能的影响，为康复治疗和预防提供依据。

英文翻译对照：

In summary, the causes of lower limb paralysis caused by cervical disc herniation mainly include impaired function of the ascending and descending fibers of the spinal cord, as well as insufficient blood supply to the spinal cord. Understanding these causes helps us better understand the impact of cervical disc herniation on bodily functions, providing a basis for rehabilitation treatment and prevention.