Histologic structure of the ulnar nerve in the hand.

Serial histologic sections of 20 ulnar nerves revealed broad individual variations in the number and diameter of the fascicles at all levels. The number of fascicles increased from the proximal portion to the distal portion, and interfascicular and perifascicular connective tissue occupied about 50% of the entire nerve section. These configurations explain the difficulties and setbacks encountered in the repair of injuries to the ulnar nerve. The counting of myelinated nerve fibers also revealed a great number of variations.