This is a powerful, complex single-arm lever (Fig. 20). All mammals have seven cervical vertebrae (Table 2).
The first cervical vertebra is the atlas. It is ring-shaped with a dorsal arch, instead of the vertebral body there is a ventral arch, the transverse costal processes fused with the articular and form the wings of the atlas. On them are deep articular cranial surfaces for connection with the occipital bone of the skull and flat caudal surfaces for connection with the second cervical vertebra. Cranially on each wing of the atlas there are intervertebral and wing openings connected by a groove, and at the base of the wing there is an intervertebral foramen. In ruminants it is absent, in a horse it is directed from top to bottom, in a pig it begins on the caudal surfaces of the wings of the atlas and leads into the wing pit.
The second cervical vertebra is the axial vertebra ( epistrophy ). It is characterized by the presence of a tooth instead of the head and crest instead of the spinous process. In ruminants, the tooth is in the form of a half-cylinder, in horses it is chisel-like, in pigs it is blunt, conical. In horses, the crest of the axial vertebra is bifurcated and fused with the caudal articular processes. In a pig, the crest of the axial vertebra is narrow, high, directed caudally.
he characteristic signs of the third and fifth cervical vertebrae are as follows: massiveness, tetrahedral shape due to the strong development of the articular processes and bifurcated transverse costal processes, at the base of which is the transverse opening. The spinous processes are directed cranially. For cattle and horses, highly developed heads and fossa of the vertebrae are typical. In ruminants, the spinous processes are highly developed, the length and width of the vertebral body are almost the same. In horses, the spinous processes are poorly developed and the vertebral body is longer than the width. Pigs are characterized by a shortened shape of the vertebral bodies with flat heads and fossae, costal processes are much longer than the bodies.
Sixth cervical vertebra – in ruminants and pigs, the rib process is lamellar, directed ventrally, in horses the transverse costal process has three branches.
The seventh cervical vertebra has one pair of costal facets at the caudal end of the vertebral body, there are transverse processes, there is no transverse opening.
Thoracic department. It includes full bony segments, i.e., in addition to the thoracic vertebrae, there are ribs, a sternum that form the chest.
The thoracic vertebrae are characterized by the presence of three pairs of facets for the ribs (along the pair on the sides of the head and fossa of the vertebral bodies and on the transverse processes), high spinous processes caudally directed (Fig. 21). On the vertebrae of ruminants there are lateral intervertebral openings, the length of the vertebral body exceeds its width. In horses, the length and width of the vertebral body are almost equal. In pigs, openings directed dorsoventrally are located at the base of the transverse processes. The heads and pits of the vertebral bodies in ruminants and horses are more pronounced than in pigs.