Which spinal nerves are involved in difficulty with the extension of the index finger?

Which spinal nerves are involved in difficulty with the extension of the index finger?

• A. C5 and C6
• B. C6 and C7
• C. C7 and C8
• D. C8 and T1

Answer: (C)

The correct response relates to the control of finger extension, particularly for the index finger, which is primarily governed by the radial nerve. The radial nerve arises from the brachial plexus and is predominantly composed of fibers from the C5, C6, C7, C8, and T1 spinal roots, but its most significant contribution for finger extension comes from the C7 root. When focusing on the extension of the index finger, C7 plays a central role since it innervates the extensor muscles responsible for this movement. The primary muscle involved is the extensor digitorum, which extends all the fingers including the index. If there is difficulty in extending the index finger, it suggests an impairment along the pathways that support this specific motion, indicating an involvement of the C7 spinal nerve. While C8 and T1 are also part of the nerve roots associated with the hand and finger function, they are more closely related to movements of the pinky and other intrinsic hand muscles rather than the primary extensor function relevant to the index finger. Therefore, C7 is the most directly responsible for this type of movement, confirming that C7 is essential in this context.

The correct response relates to the control of finger extension, particularly for the index finger, which is primarily governed by the radial nerve. The radial nerve arises from the brachial plexus and is predominantly composed of fibers from the C5, C6, C7, C8, and T1 spinal roots, but its most significant contribution for finger extension comes from the C7 root.

When focusing on the extension of the index finger, C7 plays a central role since it innervates the extensor muscles responsible for this movement. The primary muscle involved is the extensor digitorum, which extends all the fingers including the index. If there is difficulty in extending the index finger, it suggests an impairment along the pathways that support this specific motion, indicating an involvement of the C7 spinal nerve.

While C8 and T1 are also part of the nerve roots associated with the hand and finger function, they are more closely related to movements of the pinky and other intrinsic hand muscles rather than the primary extensor function relevant to the index finger. Therefore, C7 is the most directly responsible for this type of movement, confirming that C7 is essential in this context.