The purpose of this investigation was to determine the amount of epineurium surrounding the recurrent
laryngeal nerve (RLN) compared with a limb nerve, that to flexor hallicus longus (NFHL). Nerve samples
were obtained from 10 adult dogs and studied using scanning electron microscopy and light microscopy to
measure the relative proportion of epineurium and the relative proportions of adipose and collagenous tissue
comprising the epineurium in both nerves. Significantly greater relative epineurial cross-sectional areas and
adipose content were found in the RLN than in the NFHL. Based on observations on noncranial peripheral
nerves, the findings indicate that the RLN is better protected against deformational forces associated with
compression than stretching forces. The RLN may not be structured well for successful reinnervation after
injury. The patterns observed for adipose tissue in RLN epineurial tissue appeared unique compared with
those previously reported in peripheral nerves. The primary role associated with adipose tissue is to
‘package’ the nerve for protection. The RLN is considered to be a vital nerve in the body, as are other
cranial nerves. The large proportions of adipose tissue in the epineurium may relate to the importance of
protecting this nerve from injury.