**Core Concept**
Thoracic outlet syndrome (TOS) is a condition characterized by compression, injury, or irritation of the nerves and/or blood vessels that travel through the thoracic outlet, the space between the collarbone (clavicle) and the first rib. The cervical rib is an extra rib that can cause compression of the nerves and blood vessels in this region, leading to symptoms of TOS.

**Why the Correct Answer is Right**
The symptoms of TOS in cervical rib are primarily produced due to compression of the lower part of the brachial plexus, specifically the C8 and T1 nerve roots. The brachial plexus is a complex network of nerves that arise from the spinal cord and travel down the arm, providing motor and sensory function. Compression of the C8 and T1 nerve roots can lead to symptoms such as numbness, tingling, and weakness in the hand, particularly in the ulnar nerve distribution.

**Why Each Wrong Option is Incorrect**
**Option A:** Compression of the C5 and C6 nerve roots is more commonly associated with suprascapular nerve compression and is not typically seen in cervical rib-induced TOS.
**Option B:** The C7 nerve root is not typically involved in cervical rib-induced TOS, as it is usually compressed in other conditions such as cervical spondylosis or cervical disc herniation.
**Option C:** The T2 nerve root is not typically involved in cervical rib-induced TOS, as it is usually compressed in other conditions such as thoracic disc herniation.

**Clinical Pearl / High-Yield Fact**
A key clinical feature of cervical rib-induced TOS is the presence of ulnar nerve symptoms, such as numbness or tingling in the little finger, which can be a useful diagnostic clue.

**Correct Answer:** C. Compression of the C8 and T1 nerve roots is the most common cause of symptoms in thoracic outlet syndrome due to a cervical rib.