Aim: To compare the osseous anatomy of the craniovertebral junction of a horse, deer, and tiger with that of a human being. The variation in the structure of bones in these animals is analyzed.
Materials and methods: Various dimensions of the bones of the craniovertebral junction of the horse, deer, and tiger were quantitatively measured, and their differences with those of human bones were compared and analyzed.
Results: Apart from the sizes and weights, there are a number of structural variations in the bones of these animals that depend on their functional needs. The more remarkable difference in joint morphology is noticed in the occipitoatlantal joint. The occipitoatlantal articulation is remarkably large and deep, resembling a 'hinge joint' in all the three animals studied. The odontoid process is 'C shaped' in the deer and horse and is 'denslike' in the tiger and humans. The transverse processes of the atlas are in the form of large wings in all the three animals. The arches of the atlas are large and flat, but the traverse of the vertebral artery resembles, to an extent, to that of human vertebral artery. The rotatory movements of the head at the craniovertebral junction are wider ranged in the horse and deer as compared with those of the tiger and humans. The bones of the craniovertebral junction of all the three animals are adapted to the remarkable thickness and strength of the extensor muscles of the nape of the neck.
Conclusions: Despite the wide variations in the size of the bones, the basic patterns of structure, vascular and neural relationship, and joint alignments have remarkable similarities and a definite pattern of differences.
Keywords: Animals; atlas; axis; craniovertebral junction; odontoid process.