Final answer:
Cervical disk herniation is a medical condition where the nucleus pulposus of an intervertebral disc protrudes through a weakened anulus fibrosus, potentially causing pain, numbness, or muscle weakness in the neck and upper limbs.
Step-by-step explanation:
Cervical disk herniation refers to a condition in which the nucleus pulposus, the gel-like central part of an intervertebral disc, protrudes through a weakened part of the anulus fibrosus, the disc's outer layer. This usually occurs when the spine is subjected to strain or pressure, such as bending forward and lifting a heavy object. A herniation in the cervical area (near the neck) can lead to symptoms such as pain, numbness, or muscle weakness in the neck and upper limbs.
Intervertebral discs are like cushions between vertebrae, absorbing shocks from daily movements and allowing some degree of motion. However, with injury or age, the anulus fibrosus can weaken, allowing the nucleus pulposus to bulge out posteriorly, leading to what is commonly described as a 'slipped' disc. When this herniation compresses a spinal nerve, particularly at a point where it exits through the intervertebral foramen, it can cause significant discomfort and disability. Herniation most commonly occurs in the lower back (L4/L5 or L5/S1), but cervical herniation (C5/C6 or C6/C7) can result in upper body symptoms.