Veterinary Gross Anatomy

THORACIC VERTEBRAE
(Ox, Sheep and Goat, Horse, Pig, Dog, Rabbit, Fowl)

Ox

• They are 13 in number and the characteristic features of these vertebrae are the great development of neural spines, the presence of capitular facets on the body and tubercular facets on the transverse processes for articulation with the ribs.
• The bodies are shorter. On the sides of the articular ends of the body both before and behind are concave articular facets -the costal or capitular facets which with those of the adjacent vertebrae and the intervertebral disc form capitular or costal cavities for articulation with the heads of ribs. The anterior notches of the pedicle are shallower and the posterior ones are converted into foramina in the posterior series.
• The articular processes are small.The anterior ones are represented by small oval facets on the anterior part of the arch except in the first one where they surmount the transverse processes. The posterior ones spring from the base of the spinous process.
• The transverse processes though prominent do not always articulate with ribs.
• The spinous process is very long and of enormous size, which is characteristic of the vertebrae of this region. Each is a flattened plate, which serves for the attachment of the spinal muscles and ligaments.

Special Features:

• The anterior vertebrae in the series bear rounded mammillary processes.
• The spine of the first is very long and is usually pointed. The spines of the next two are the longest and behind these they gradually diminish in height. The backward slope, which is at first, slight and then increase to the tenth. The last dorsal has a vertical spine.
• The tubercular facets gradually decrease in size from before backwards.
• The last dorsal has no posterior capitular facets.

TOP

Sheep and Goat

• They are usually 13 in number.
• The bodies are relatively wider and less constricted than those of the ox.
• The intervertebral foramina are relatively larger in correlation with the absence of foramen, which usually occur in the arches of these vertebras in ox.

TOP

Horse

• They are 18 in number.
• The bodies are shorter.
• The spine of the first is shorter and curved backward.
• The spinous processes increase in length to the third and fourth, then gradually diminish to the fifteenth beyond which they are about the same in height.
• The backward inclination of the superior spine is most pronounced in the second, the sixteenth is vertical and those of the last two are directed slightly forwards.
• The last four or five show a distinct mammillary process.

TOP

Pig

• The bodies are relatively long and constricted in the middle.
• The ventral spine is absent.
• Mamillary process is present except in the first two.
• The last transverse process is lumbar in character.
• Small accessory process occurs in the posterior part of the region.

TOP

Dog

• The bodies are wider and compressed dorso-ventrally.
• The transverse processes in the posterior of the series bear mamillary processes and in the last three accessory processes also.
• The posterior facets on the bodies for the heads of the ribs are absent on the last two or three, so that the head of each of the last three ribs articulates with only one corresponding centrum.

TOP

Rabbit

• 12 in number.

TOP

Fowl

• They are seven in number.
• The first and the sixth are free, second to the fifth are fused into one piece. The seventh is fused to the lumbo-sacral segment.
• Each vertebra presents a complete capitular cavity for the corresponding rib.
• The superior and inferior spines are well developed and are fused from the second to the fourth.
• The transverse processes are plate like and present tubercular facets, at their free ends. Thin plates of bone fill the gaps between the transverse processes.

TOP