Which anatomical feature is cautioned against at LI-15?

The anatomical feature that is cautioned against at LI-15 is the axillary nerve. LI-15, also known as Jianyu, is located in the anterior aspect of the shoulder joint, and care must be taken when palpating or needling in this area due to the proximity of the axillary nerve. This nerve innervates the deltoid muscle and provides sensation to the skin overlying the lower part of the deltoid and the lateral aspect of the shoulder. Injury or inadvertent damage to the axillary nerve can lead to complications such as weakness in shoulder abduction and sensory loss in the area it supplies.

Understanding the location and function of the axillary nerve is crucial for practitioners to avoid potential neurological injuries during acupuncture treatments. It's important to be mindful of this nerve while administering techniques around the shoulder, ensuring effective treatment while minimizing risks to the patient's nerves and surrounding structures.