Ulnar nerve dimensions at entrapment sites in cadavers

The ulnar nerve might undergo compression due to traumatic or non-traumatic pathological conditions or altered anatomy within the extent of the distal arm to the proximal hand, leading to ulnar neuropathy. There are certain anatomical sites where the increased ulnar nerve cross-sectional area (CSA) values indicate probable compression and can be diagnosed by the high-resolution Ultrasonography (USG) or Magnetic Resonance Imaging (MRI) in symptomatic patients. The ulnar nerve CSA varies across the population, and there is limited data available for the Indian population. Hence, we aimed to evaluate the CSA measurement of the ulnar nerve in various predefined anatomical sites.

The CSA of the ulnar nerve was studied in 64 (34 Male, 30 Female) formalin-fixed cadaveric upper limbs in various predefined anatomical sites. The statistical analysis was done using Microsoft Excel and Stata 12 software.

The average CSA of the ulnar nerve was 4.77 ± 2.21 mm² at the level of the medial epicondyle and 2.21 ± 0.86 mm² at the level of the wrist. The CSA values were higher in males than in females. This study has also reported the distances of the branch points of the ulnar nerve supplying the flexor carpi ulnaris and flexor digitorum profundus muscles, the dorsal cutaneous and palmar cutaneous branches from the nearest bony landmarks.

Thus, this study provides a baseline value of ulnar nerve CSA for the East Indian population, which might help clinicians to diagnose ulnar neuropathy.