Final answer:
The exact percentage of cervical ribs causing Thoracic Outlet Syndrome (TOC) is not provided; cervical ribs are rare and only a minority with these ribs develop TOC. The thoracic cage's structure and limited range of motion of thoracic vertebrae generally prevent neurovascular compression syndromes like TOC.
Step-by-step explanation:
The question refers to the prevalence of Thoracic Outlet Syndrome (TOC) in individuals with cervical ribs. While the exact percentage is not stated in the provided materials, cervical ribs are an additional set of ribs that can develop above the normal first rib, arising from the seventh cervical vertebra. These anomalies are relatively rare and are present in less than 1% of the population. However, when present, cervical ribs can contribute to neurovascular compression and may cause thoracic outlet syndrome, although only a minority of people with cervical ribs will experience TOC.
The thoracic cage comprises 12 pairs of ribs and the sternum. The ribs are classified as true ribs (1-7) and false ribs (8-12), with the false ribs including two pairs of floating ribs (11-12). The rib cage provides support and protection for the thoracic organs and contributes to the breathing process. Moreover, the thoracic vertebrae feature a specifically designed structure which limits their range of motion compared to the cervical vertebrae. This structural design of the thoracic vertebrae, in concert with the associated rib cage, decreases the likelihood and range of thoracic movements that might otherwise contribute to neurovascular compression syndromes like TOC.
A better understanding of the anatomical and physiological relationship between the cervical ribs and thoracic outlet syndrome is necessary to determine the precise percentage of individuals with cervical ribs who will develop TOC.