Figure 2: Images of the craniovertebral junction bones of a horse. (a) Inferior view of the posterior aspect of the skull showing the large occipital condyles (1). (b) Superior (anterior) surface of the atlas, as seen from the superior and anterior perspective, showing the deep 'cup-shaped' articular surface (1) for the articulation with occipital condyles. (c) Inferior surface showing the atlas articulated with the occipital bone. Note the acute flexed position of the head in relationship with the atlas. (d) Posterior view showing the occipitoatlantal articulation. (e) Ventral view of the C1 vertebra showing the ventral arch (1), ventral tubercle (2), transverse process (3), transverse foramen (4), atlantal fossa (5), and superior articular facets (6). (f) Dorsal view of the C1 vertebra showing the dorsal arch (1), the inferior articular facets (2), transverse foramen (3), alar foramen (4), and lateral vertebral foramen (5). (g) Superior view of the axis vertebra of the horse showing the C-shaped configuration of the odontoid process (1) and the deep impressions for the longitudinal ligament (2). The superior articular facets of the axis are seen in relationship with the odontoid process. (h) Anterior view of the C1-C2 articulation. The atlantoaxial joints are relatively flat when compared with the deep concavity of the superior facets of the atlas in relationship with the occipital bone. (i) Posterior view of the C1-C2 articulation. (j) Lateral view of the C1-C2 bones. The notch for the C2 spinal nerve is converted into the lateral vertebral foramen (1) following ossification of the ligament.