Peripheral nerve injury can vary wildly in severity and presentation, ranging from mild soreness to severe muscle weakness. Axillary nerve injuries typically respond well to conservative management, though a surgical intervention may be required. Failure to accurately diagnose and manage patients may lead to life-long disability that can affect the overall quality of life. While axillary nerve lesions are somewhat rare, they should be considered when patients present with shoulder weakness and sensory loss. The axillary nerve diverges from the posterior cord of the brachial plexus anterior to the subscapularis muscle, running posterior to the axillary artery. It then travels inferior to the glenohumeral joint capsule and passes through the quadrangular space with the posterior humeral circumflex artery. The axillary nerve proceeds to split into anterior and posterior divisions. The anterior division supplies motor innervation to the anterior and middle heads of the deltoid. The posterior division provides motor innervation to the posterior deltoid and teres minor before eventually terminating as the superior lateral cutaneous nerve and innervating the lateral shoulder. The axillary nerve is a bilateral upper extremity peripheral nerve and receives significant contributions from C5 and minor contributions from C6. As stated above, the axillary nerve innervates the deltoid and teres minor muscles. The deltoid muscle, divided into three parts, performs and assists in a variety of actions. The primary function of the deltoid muscle is glenohumeral abduction, performed by the middle muscle belly. The anterior muscle belly assists in glenohumeral flexion and internal rotation. The posterior muscle belly assists in glenohumeral extension and external rotation. The teres minor functions in glenohumeral external rotation. The deltoid and teres minor stabilize the glenohumeral joint, with the teres minor contributing a greater role as a part of the glenohumeral rotator cuff. Lastly, the axillary nerve transmits afferent sensory input from the lateral shoulder. Several studies have claimed the axillary nerve innervates the long head of the triceps brachii. Still, a recent cadaver study by Wade et al. showed no axillary nerve innervation to the triceps brachii.
周围神经损伤的严重程度和表现差异很大，从轻微酸痛到严重肌肉无力不等。腋神经损伤通常对保守治疗反应良好，不过可能需要进行手术干预。未能准确诊断和治疗患者可能导致终身残疾，影响整体生活质量。虽然腋神经损伤 somewhat rare，但当患者出现肩部无力和感觉丧失时，应考虑这种情况。腋神经在肩胛下肌前方从臂丛后束分出，在腋动脉后方走行。然后它下行至肩肱关节囊下方，与旋肱后动脉一起穿过四边形间隙。腋神经接着分成前支和后支。前支为三角肌的前、中头提供运动神经支配。后支在最终成为上臂外侧皮神经并支配肩部外侧之前，为三角肌后束和小圆肌提供运动神经支配。腋神经是双侧上肢周围神经，主要由C5支配，也有少量来自C6的支配。如上所述，腋神经支配三角肌和小圆肌。三角肌分为三部分，执行并协助多种动作。三角肌的主要功能是肩肱关节外展，由中间肌腹完成。前肌腹协助肩肱关节屈曲和内旋。后肌腹协助肩肱关节伸展和外旋。小圆肌的功能是肩肱关节外旋。三角肌和小圆肌稳定肩肱关节，小圆肌作为肩肱旋转袖的一部分发挥更大作用。最后，腋神经传递来自肩部外侧的传入感觉信息。几项研究声称腋神经支配肱三头肌长头。然而，韦德等人最近的一项尸体研究表明，腋神经并不支配肱三头肌。
