What is the primary concern if the long thoracic nerve is damaged during axillary node dissection?

The primary concern when the long thoracic nerve is damaged during axillary node dissection is the development of a winged scapula. The long thoracic nerve innervates the serratus anterior muscle, which is responsible for holding the scapula against the thoracic wall and facilitating shoulder movement. When this nerve is compromised, the serratus anterior muscle becomes weak or paralyzed, leading to the characteristic winged appearance of the scapula, especially when the patient extends their arm forward or pushes against a surface.

The other options, while they reflect potential issues that can arise from different nerve injuries, do not pertain to the long thoracic nerve. Loss of hand grip strength may be related to injuries affecting other nerves such as the radial or ulnar nerves, numbness in the forearm typically involves nerve paths associated with the median or ulna, and diminished sensation in the shoulder would likely relate to the supraclavicular nerves or the axillary nerve, not the long thoracic nerve. Thus, the correct answer highlights the specific anatomical and functional consequences of damage to the long thoracic nerve.