To investigate the skilled functional outcome, limb muscle reinnervation model was designed (Figures 1(a) and 1(b)). Briefly, all rats were anesthetized with isoflurane (1.5–2%) and a mixture of 30% N2O and 70% O2. With the longitudinal incision at the right proximal upper limb, the musculocutaneous nerve (MCN) and the radial nerve were exposed before their innervation of the biceps muscle and the triceps muscle, respectively. For the nerve injury group, both nerves were transected and tightly ligated to prevent the nerve stump regeneration. For the nerve repair group, both nerves were exposed in the same fashion. Then, the stumps of both nerves were immediately anastomosed through a 10-0 monofilament epineurial microstitch (Ethicon, USA) following the nerve transection. For the control group, sham operations were performed, where MCN and radial nerve were exposed as in the injury group, but received no further manipulations.

The surgical procedure of the raw forepaw. (a) To assess the skilled functional recovery outcome after peripheral neural repair, we designed a nerve anastomosis model using rat forelimb. (b) The musculocutaneous nerve (MCN) and radial nerve of the rat forelimb were resected with or without nerve repair, to investigate the impact of limb muscle denervation and reinnervation on the skilled limb function. (c) Similarly, the median nerve and the ulnar nerve were manipulated to study the denervation and reinnervation of the paw intrinsic muscle.