This study intends to have experts with over 10 years of experience in ultrasound-guided regional anesthesia acquire 1,000 target images. These images will be annotated by both an AI model and human experts, and the model's annotations will be evaluated by a panel of 10 specialists. The primary outcome is the accuracy of identifying the target anatomical structures in the annotated images. Secondary outcomes include the number of true positive, false positive, true negative, and false negative structures, the time required for annotation, and the potential application of the AI model in assisting the performance of ultrasound-guided regional blocks.

Inclusion Criteria:

• Aged 18-70 years
• BMI between 19-23 kg·m-²
• ASA physical status classification I-II
• Normal orientation and able to cooperate with physical examination.

Exclusion Criteria:

• Patient refusal
• Infection, trauma, skin defect, deformity, or other abnormalities at the intended nerve block site
• Pregnancy