Radiological Study of the Movements of the Cervical Spine in the Dog Compared with Those in Man

Six dogs were used for a radiological investigation of movement of the cervical vertebrae for comparison of range of motion, instantaneous centers of motion and patterns of flexion and extension with those determined for man. Five dogs were embalmed and one live dog was investigated under the influence of general anesthesia. All animals were adult with the exception of one of the embalmed animals. None of the animals exhibited any abnormalities of cervical vertebrae or intervertebral discs. It was demonstrated that range of motion of the dog cervical spine exceeds that of man, largely due to a greater flexion-extension range of the atlanto-occipital joint and of lateral flexion of the cranial and caudal cervical spine. Patterns of flexion and extension of the cranial and caudal cervical spine of the dog are similar to that of man with no differences in the location of centers for these movements. Other differences were primarily due to the organization of intervertebral articulations.
These relationships are discussed in regard to the significance of individual groups of cervical muscles, joint functions and influence of movement on the spinal cord.