Final answer:
Lifting heavy objects can cause a slipped disc by exerting pressure on the vertebral column, potentially leading to the compression of the sciatic nerve and resulting in sciatica symptoms such as radiating pain in the lower limb.
Step-by-step explanation:
Lifting a heavy object can produce pain in a lower limb through a mechanism known as a herniated disc, commonly referred to as a slipped disc. During the act of lifting, especially if the individual bends forward, increased pressure is placed on the vertebral column. This pressure can specifically stress the posterior aspect of an intervertebral disc, particularly if the anulus fibrosus is already weakened due to injury or age. If the gel-like nucleus pulposus protrudes or slips through this weakened anulus fibrosus, it can herniate outwards towards the spinal nerve. The herniation can then compress the nerve, as would occur with the sciatic nerve in the case of sciatica, causing radiating pain from the lower back through the leg, and potentially causing muscle weakness. Such a scenario is more common in the lumbar region, particularly at the L4/L5 or L5/S1 levels. Treating a herniated disc might involve removing the damaged part of the disc or, in some cases, replacing it with an artificial disc to allow continued movement between the vertebrae.