Background: This study compared the quality and duration of analgesia between the superior trunk (ST) and the clavipectoral fascial plane (CFP) blocks in conjunction with a selective supraclavicular nerve (SCN) block for clavicular surgeries. Methods: Fifty patients undergoing mid-third clavicular procedures were randomly assigned to the ST group (received an SCN block followed by blockage of the ST of the brachial plexus) and the CFP group (received an SCN block followed by the CFP block). The primary outcome was the time until the first rescue analgesia. Secondary outcomes included total nalbuphine dosage and numerical rating scale (NRS) scores within the first 24 hours, the onset of sensory block, as well as deltoid and biceps muscle function using the modified Bromage score (MBS), diaphragmatic excursion, along with satisfaction levels. Results: The ST group exhibited a more prolonged duration until the first request for rescue analgesia compared to the CFP group (18.76 ± 0.89 hours vs. 15.34 ± 1.38 hours), with a mean difference of 3.42 hours (95% confidence interval: 2.76 to 4.08, P < 0.001). The ST group consumed less nalbuphine and reported lower NRS scores at 6, 8, 12, 16, and 24 hours than the CFP group. Additionally, the ST group exhibited a lower MBS and diaphragmatic excursion than the CFP group. However, the differences in the onset of sensory block and satisfaction levels were not statistically significant. Conclusions: The ST group demonstrated superior outcomes in pain control with less favorable outcomes concerning diaphragmatic excursion and upper limb motor function.