What problem may arise from the presence of a cervical rib?

The presence of a cervical rib can lead to compression of the subclavian artery, which is located in the neck region and is responsible for supplying blood to the upper limb. When a cervical rib is present, it may encroach on the space through which the subclavian artery passes, resulting in vascular compression. This compression can cause ischemic pain due to reduced blood flow to the arm and hand. Patients might experience symptoms like numbness, tingling, or pain in the upper limb, especially during activities that exacerbate the compression.

In contrast, the other options do not accurately reflect the physiological implications of a cervical rib. Increased blood flow to the upper limb would not occur as a cervical rib typically causes a restriction, not an enhancement, of blood supply. Stimulation of the vagus nerve is unrelated, as the vagus nerve is not typically affected by the presence of a cervical rib. Similarly, a cervical rib does not strengthen the brachial plexus; rather, it can potentially lead to nerve compression and associated neurological symptoms. Thus, the risk of vascular compression leading to ischemic pain is a significant clinical concern associated with the presence of a cervical rib.