THE ARTICULATIONS OF THE HORSE—INTERCENTRAL ARTICULATIONS i i | 
THE ARTICULATIONS OF THE HORSE 
JOINTS AND LIGAMENTS OF THE VERTEBRZE 
The movable vertebre form two sets of articulations, viz., those formed by the 
bodies, and those formed by the articular processes of adjacent vertebrie; the 
former are termed intercentral, and the latter interneural. Associated with these 
are ligaments uniting the arches and processes; some of these are special, 7. e., con- 
fined to a single joint, while others are common, 7. e., extend along the entire ver- 
tebral column or a considerable part of it. The joints between the atlas and axis 
and between the former and the skull require separate consideration. 
INTERCENTRAL ARTICULATIONS 
These are amphiarthroses, formed by the junction of the extremities of the 
bodies of adjacent vertebree. The articular surfaces in the cervical region consist 
of a cavity on the posterior 
end of the body of the anter- ; 
ior vertebra, and a correspond- See Z 
ing convexity or head of the ment \ 
succeeding vertebra. In the \ 
other regions the surfaces are 
much flattened. The uniting 
media are: 
1. The intervertebral 
fibro-cartilages (Fibrocartila- 
gines intervertebrales). Each 
of these is a dise which fits into { 
the space between the bodies 
of two adjacent vertebree, to 
which it is intimately attached. 
The dises are thinnest in the Fic. 230.—Sacirrat Section or Last Two TxHoracic anp First 
middle of the thoracic region, LumBark VERTEBR£, SHOWING LIGAMENTS AND SpInaAL Corp 
thicker in the cervical and lum- (Meputta). (After Schmaltz, Atlas d. Anat. d. Pferdes.) 
bar regions, and thickest in the 
coceygeal region. Each consists of a peripheral fibrous ring (Annulus fibrosus) 
and a soft central pulpy nucleus (Nucleus pulposus). 
The fibrous ring consists of lamin of fibrous tissue and fibro-cartilage, which pass obliquely 
between the two vertebrie and alternate in direction, forming an X-shaped arrangement. The 
central part of the ring is largely cartilaginous, and gradually assumes the character of the pulpy 
center. The latter is very elastic and is compressed, so that it bulges considerably from the sur- 
face of sections; it consists of white and elastic fibers, connective-tissue cells, and peculiar clear, 
transparent cells of various sizes. It is a remnant of the notochord. There are joint cavities in 
the cervical intercentral joints, and in those between the last cervical and the first thoracic, and 
between the last lumbar and the sacrum. 
2. The ventral longitudinal ligament (Lig. longitudinale ventrale)! lies on the 
ventral surface of the bodies of the vertebre and the intervertebral fibro-car- 
tilages, to which it is firmly attached. It begins to be distinct a little behind the 
middle of the thoracic region, and is at first a narrow, thin band. Further back 
it becomes gradually thicker and wider, and terminates on the pelvic surface of 
the sacrum by spreading out and blending with the periosteum. It is strongest in 
the lumbar region, where the tendons of the crura of the diaphragm fuse with it. 
3. The dorsal longitudinal ligament (Lig. longitudinale dorsale)? lies on the 
floor of the vertebral canal from the axis to the sacrum. It is narrow over the mid- 
1 Also termed the inferior common ligament. 
2 Also termed the superior common ligament. 
