Ultrasonographic Anatomy, Electrophysiological and Histological Studies on Sciatic Nerve in Dog

The sciatic nerve is the major mixed nerve of the canine hind limb. It supplies most of the hind limb musculature. Sciatic nerve morphology and ultrasound guide surgeons and clinicians who contribute to the neurological examination of the sciatic nerve. So, the current study aimed to provide a fully descriptive ultrasonographic anatomy of the normal sciatic nerve in dogs and to set the motor conduction reference values of this nerve. Ultrasonography and neurography were applied to five adult healthy male dogs; two of them were euthanized for morphological and histological studies to describe the origin, branches, and innervated muscles of the sciatic nerve. The sciatic nerve originates from the ventral branches of the L6, L7, and S1 spinal nerves, splitting into muscular and sural branches, and is terminated by the perineal and tibial nerves. The normal sciatic nerve appears to have a hypoechoic core surrounded by hyperechoic bundles. The mean of the estimated electrophysiological parameters of the tibial and common fibular nerves was 2.20, 4.88, 20.08, 67, and 2.50, 7.78, 14.82, and 72.80 for the duration, latency, amplitude, and conduction velocity, respectively. Histological evaluation of the sciatic nerve revealed several nerve fasciculi surrounded by an epineural connective tissue sheath. The study provides a professional descriptive evaluation of the ultrasonographic anatomy of the sciatic nerve from its origin until divergence at the distal femur, which facilitates sciatic nerve evaluation for beginners and practitioners. The study also provides a full description of the neurographical and histological data of the normal sciatic nerve in dogs, which can be used as reference values for comparison with dogs that suffered sciatic nerve injuries.