125 
' ANATOMY OF THE IIOKSE. 
closing the smooth cartilaginous surfaces of the articulatory pro¬ 
cesses ; 6th, The intervertebral fibro-cartilages, forming the prin¬ 
cipal bond of union between the vertebrae (so strong a one, that 
( rather than this substance will part from its attachments, the 
bone itself will give way), consist of so many dense, concentric, 
fibrous substances, interposed between the bodies of the vertebrae, 
to the surfaces of which they are most firmly and inseparably in¬ 
herent. In form, they correspond to the bones, but in thickness 
and volume they differ in each vertebral region. The fibres are 
found to cross and intercross one another, and to be so disposed 
as to leave in the centre spaces which are filled with a soft, pulpy, 
elastic tissue, which adds to facility of motion ; 7th, Ligamentum 
A uchce vel Subfavum , an elastic ligamentous substance, reaching 
from the occiput to the coccyx. It arises from the occipital tu¬ 
berosity, and there consists of a cylindrical chord. It is conti¬ 
nued backward along the superior border of the neck, and 
stretches broader and broader as it proceeds, in order to reach 
down to the spinous processes, to all of which (with the exception 
of the first) it is fixed. It is broadest at the dip made by the 
spine in front of the withers. As it approaches the tallest dorsal 
spine it narrows, and, after having passed the sixth or seventh, again 
becomes a chord, or rather a band, whose greatest breadth is cross¬ 
wise. It passes onward, covering and connecting the remaining 
superior spines of the back, and also those of the loins, sacrum, 
and coccyx, growing upon the last bone gradually smaller and 
smaller, and ultimately vanishing upon its extremity. Being 
highly elastic, it will admit of all the motions the spine is suscep¬ 
tible of, while it has a continual tendency to maintain or recover 
its original or natural form. 
Articulations of the thorax. —The vertebral extremity 
of the rib forms three distinct and separate joints with the spine, 
and is further maintained by two ligaments :—1st, Capsular mem¬ 
brane of the heady in its attachment surrounds and includes the 
whole of the head ; but sends off a process, internally, by which 
the surface opposed to one vertebra is formed into a synovial ca¬ 
vity, distinct from that which is adapted to the other vertebra 
next to it. This part of the union is strengthened by some liga¬ 
mentous fibres which spring from the summit of the head ; 2d, 
Capsular membrane of the tubercle, surrounds the process at its 
articulation with the transverse process of the vertebrae ; 3d, Ex¬ 
ternal ligament, fixing the neck of the rib to the spine, exter¬ 
nally ; 4th, Internal ligament, a similar one, internally. 
The cartilages of the true ribs which are attached immediately 
to the sternum, are received into the cups on the lateral borders 
of that bone, and maintained there by — 1st, Ligamentous ex - 
