Questions: The left and right brachial plexuses are networks of nerves that supply the - upper limb - neck - abdomen - thorax

The answer is the first one: upper limb.

Explanation for each option:

• Upper limb: Correct. The brachial plexus is a network of nerves that supplies the upper limb, including the shoulder, arm, forearm, and hand.
• Neck: Incorrect. The brachial plexus does not supply the neck; instead, the cervical plexus is responsible for innervating the neck region.
• Abdomen: Incorrect. The brachial plexus does not supply the abdomen. The abdominal region is primarily innervated by the lumbar and sacral plexuses.
• Thorax: Incorrect. While some nerves from the brachial plexus may have branches that affect the thoracic region, the primary supply to the thorax comes from the intercostal nerves, not the brachial plexus.

In summary, the brachial plexus is primarily responsible for innervating the upper limb.