A patient who has undergone a radical mastectomy with extensive axillary dissection exhibits winging of the scapula when she pushes against resistance on an immovable object, such as a wall. Injury of which of the following nerves would result in this condition?

(c) Source: GAS 690, 704, 768; GA 361, 370-371The long thoracic nerve arises from the C5, C6, and C7 spinal nerves and innervates the serratus anterior muscle. Injury of this nerve will result in a characteristic winged scapula. A is the lateral pectoral nerve, which innervates the pectoralis major muscle. B is the suprascapular nerve, which innervates the supraspinatus and infraspinatus muscles. D is the thoracodorsal nerve, which innervates latissimus dorsi. E is the lower subscapular nerve that innervates the lower part of the subscapularis muscle and the teres major.