Which syndrome is characterized by loss of motor function below the level of injury and preservation of sensations carried by the posterior columns?

The correct choice is anterior cord syndrome. This syndrome is characterized by a specific pattern of neurological deficits following an injury to the anterior two-thirds of the spinal cord. In anterior cord syndrome, there is loss of motor function and pain and temperature sensation below the level of injury due to damage to the corticospinal and spinothalamic tracts. However, proprioception and vibration sensation, which are carried by the posterior columns, remain intact. This unique preservation of sensations from the posterior columns is a defining feature that differentiates anterior cord syndrome from other spinal cord syndromes.

In contrast, Brown-Séquard syndrome involves hemisection of the spinal cord, resulting in ipsilateral loss of motor function and proprioception, along with contralateral loss of pain and temperature sensation. Central cord syndrome typically presents with greater upper extremity weakness compared to lower extremities but does not preserve motor function entirely as seen in anterior cord syndrome. Lastly, cauda equina syndrome results from injury to the peripheral nerves of the cauda equina and mainly causes lower limb weakness, sensory loss, and bladder dysfunction rather than the specific patterns seen in anterior cord syndrome.