CompAnat: Chapter 2.5

vertebral column

composed of a series of unpaired bones, the vertebrae, the number of which varies between domestic mammals.

Cervical, Thoracic, Lumbar, Sacral, Caudal

Vertebrae of the different regions

Vertebral regions

have to fulfill different functions and therefore have individual characteristics, all vertebrae share a common basic structure

Irregular bones

The vertebrae are classified as

Spongy substance

Middle of vertebra

Compact bones

Surrounds the vertebra

Body, Arch, Processes

Each vertebra consists of the following:

Intervertebral fibrocartilagenous discs

are interposed between adjacent vertebrae.

vertebral foramina

correspond with that of adjacent vertebrae to form the vertebral canal

vertebral canal

surrounds the spinal cord, its meninges, spinal nerves, blood vessels, ligaments, fat and connective tissue

Atlantooccipital space, Atlantoaxial space, Lumbosacral space

Three sites in the vertebral column where an interarcuate space is formed between the arches of adjacent vertebrae.

Cerebrospinal fluid

Three sites in the vertebral column are of clinical importance, since they can be used to enter the vertebral canal for injections or obtaining samples of

Atlanto-occipital space

between the occipital bone and the first vertebra (atlas)

Atlantoaxial space

between the first (atlas) and the second vertebra (axis)

Lumbosacral space

Between the last lumbar vertebra and the sacrum.

spinous process

spinous process

articular processes

positioned cranial and caudal to the root of the spinous process,

transverse processes

projecting laterally from the base of the vertebral arch, and

mammillary processes

between the transverse and cranial articular processes of the thoracic and lumbar vertebrae.

accessory processes

between the transverse and the caudal articular processes of the last thoracic vertebrae (carnivores and pigs) and the lumbar vertebrae (carnivores).

Atlas, Axis

highly modified to allow free movement of the head.

wings of the atlas

An expanded transverse process projects laterally from each mass; these shelf-like processes are termed the

wings of the atlas

provide attachment to the dorsal and ventral musculature, which is responsible for up-and-down movement of the head

Fovea dentis

The dorsal surface of the ventral arch has a caudal transverse concave articular surface

Dens

The fovea dentis articulates with this feature of the second cervical vertebra

axis

constitutes the pivot around which the atlas, and thus the head rotates

Dens

The cranial extremity of the body is characterized by the centrally located

Dens

Regarded as the displaced body of the atlas based on its development

arch of the axis

carries the elongated, expanded spinous process, which overhangs the cranial and caudal end of the vertebral body in carnivores and only the caudal end in the pig.

Ruminants

In this animal the arch of axis is a rectangular bony plate

Horse

In this animal the arch of axis bifurcates caudally

bodies

Remaining cervical vertebrae become progressively shorter from cranial to caudal

Domestic animals

In this animal, the spinous process is comparatively short

Horse

In this animal, only the seventh cervical vertebra has a distinct spinous process

thoracic spine

Composed of a chain of thoracic vertebrae.

thoracic spine

They form, partly overlapping, a slightly dorsoconvex bony rod, which is characterized by its limited flexibility.

long spinous processes

Adapted to their function the thoracic vertebrae are equipped with special anatomical features

long spinous processes

for the attachment of the strong head and neck musculature in pigs and herbivores

cranial thoracic vertebrae

fulfill an additional function as part of the entire vertebral column by transmitting the body weight to the thoracic limbs and, together with the ribs, provide attachment to the muscles of the ribs, thorax and shoulder.

Ribs

The thoracic vertebrae articulate with the

diaphragmatic or anticlinal vertebra

The thoracic vertebra, whose spinous process is nearly perpendicular to the long axis of that bone, is termed the

10th thoracic vertebra

In dogs, this is the diaphragmatic or anticlinal vertebra

12th thoracic vertebra

In pigs and goats, this is the diaphragmatic or anticlinal vertebra

13th thoracic vertebra

In ox, this is the diaphragmatic or anticlinal vertebra

16th thoracic vertebra

In horse, this is the diaphragmatic or anticlinal vertebra

lumbar vertebrae

they are longer and have a more uniform shape to their bodies

Costal Facets

In the lumbar vertebrae, these are absent

Spinous processes, craniodorsally

These are shorter in the lumbar vertebrae (Indicate direction)

Transverse process

These are long, flattened and project far laterally

Transverse myelities

swelling of the spinal cord

Caudal intumesence

The vertebral arches form a widened vertebral canal to accommodate the swelling of the spinal cord in the lumbar region

spinous processes

In lumbar vertebrae, these are usually about equal in height and inclined cranially.

Carnivores

In this animal, the first four or five lumbar vertebrae become progressively longer

Ox

In this animal, they show a caudal inclination

Small ruminants

In this animal, they are orientated perpendicular to the long axis of the vertebrae

transverse processes

the characteristic feature of the lumbar vertebrae.

Costal processes

They represent rudimentary ribs and are therefore called

first lumbar vertebra

has the shortest transverse processes.

third or fourth

The longest lumbar vertebra in most domestic mammals

fifth or sixth

The longest lumbar vertebra in carnivorse

Horse

transverse processes of the last two lumbar vertebrae and those of the last lumbar and first sacral vertebrae articulate with each other

nterarcuate spaces

Are narrow in the lumbar region,

Lumbosacral interarcuate space

wide between the last lumbar and the first sacral vertebra

cat

the interarcuate space between the last two lumbar vertebrae is also wide enough to allow injections into the vertebral canal