Table 1.
HRUS CSA of upper extremity nerves in healthy Asian adults.
| Percentiles | |||||
| Nerve | Site | Mean | SD | 2.5th, 97.5th | Reference range∗ |
| Median | Wrist | 9.33 | 1.55 | 7, 13 | 7–13 |
| Forearm | 6.31 | 1.49 | 4, 10 | 4–10 | |
| Below-elbow | 6.85 | 1.64 | 4, 11 | 4–11 | |
| Antecubital fossa | 8.96 | 2.41 | 4, 14 | 5–14 | |
| Mid-arm | 9.34 | 2.38 | 6, 15 | 6–15 | |
| Axilla | 9.88 | 2.52 | 6, 16 | 6–16 | |
| WFR | 1.57 | 2.38 | 2. 4 | 1–2.4 | |
| Ulnar | Wrist | 5.09 | 1.29 | 3, 8 | 3–8 |
| Arterial split | 5.74 | 1.42 | 4, 9 | 4–9 | |
| CT outlet | 6.93 | 1.79 | 4, 11 | 4–11 | |
| ME | 7.31 | 1.69 | 5, 11 | 5–11 | |
| Proximal 2 cm to ME | 7.11 | 1.64 | 4, 10 | 4–10 | |
| Mid-arm | 6.37 | 1.56 | 4, 11 | 4–11 | |
| Axilla | 6.94 | 1.97 | 4, 12 | 4–12 | |
| Radial | Above SG | 7.02 | 1.87 | 4, 11 | 4–11 |
| SG | 6.81 | 1.75 | 4, 11 | 4–11 | |
| Antecubital fossa | 7.26 | 1.70 | 5, 11 | 5–11 | |
| SRS | Proximal forearm | 2.50 | 0.86 | 1, 4 | 1–4 |
| PIN | Proximal forearm | 2.02 | 0.69 | 1, 3 | 1–3 |
| MACN | Mid-arm | 3.30 | 1.13 | 2, 7 | 2–7 |
| LACN | Elbow | 3.28 | 1.29 | 2, 6 | 2–6 |
| MC | Axilla | 3.81 | 1.28 | 2, 7 | 2–7 |
All values are in mm2 except WFR. The reference range is determined as the mean ± 2 SD for normally distributed data and from 97.5th percentile for non-normally distributed data. CSA = cross-sectional area, CT = cubital tunnel, HRUS = high-resolution ultrasonography, LACN = lateral antebrachial cutaneous nerve, MACN = medial antebrachial cutaneous nerve, MC = musculocutaneous nerve, ME = medial epicondyle, PIN = posterior interosseous nerve, SD = standard deviation, SG = spiral groove, SRS = superficial radial sensory, WFR = wrist-to-forearm median nerve CSA ratio.
The reference range∗ is determined ∼