Encyclopaedia Britannica, or, a Dictionary of arts, sciences, and miscellaneous literature : enlarged and improved. Illustrated with nearly six hundred engravings > Volume 8, ELE-FOR

444 FARR
Anatomy The fmall paftern-bone (2, fig. 13, T4, 15.) is about
of the hajf the length of the large one, and is as broad as it is
, °‘le' b»ng. Bofides the two concave depreffions, (/;, //, fig.
117 I3>) mentioned before, there is a ridge between them, /,
Small paf- that enters a correfpondent depreffion, g, in the lower
tom-bone, head of the large paftern-bone. The fmall paftetn-
bone has at the back and upper part (F, fig. 14.) a
jmall projeflion, for the infertion of a long ligament,
that comes from the fefamoid bones. The lower arti¬
culating furface is more extenfive than the upper, as it
is connected with the upper furface of two confiderable
bones, viz. the navicular and coffin-bone. It is of
great confequence to underftand the mechanifm of the
joints that are formed by this connection, as it is on
this part that the principal ftrefs of the animal falls.
The union of the fmall paftern-bone with the navicular
and coffin-bones, forming what is called the cojjin-joint,
is one of the principal methods provided by nature to
118 prevent concuflion.
Navicular- 'j'he navicular-bone (3, fig. 13, 14, 15.) is connect¬
ed above with the back part of the fmall paftern-bone,
and the lower edge of this bone is attached by a large
ligament to the back part of the coffin-bone. The na¬
vicular-bone is {lightly concave, to receive the back
part of the lower head of the fmall paltern-bone. The
upper edge of the navicular-bone behind is rough (g,
fig. I 4.) and thick, for the attachment of the upper liga¬
ment ; and the loweredge of the navicular-bone receives
at the back part a ftrong flat ligament from the coffin-
bone, immediately above the infertion of the flexor ten¬
don. The lower furface of the navicular-bone is cover¬
ed by cartilage, and has a fmall ridge in its centre, (/,
fig. 13.) to be received into a correfponding depreffion
in the long flexor-tendon. This bone may be confider-
ed as forming two diftinC! joints, one of which is com-
pofed by the conneClion of one part of the bone with
the tendon of the flexor-mufcle, and the other is form¬
ed by the conneClion of another furface of the navicu¬
lar-bone.
The whole weight of the animal, fupported by the
fma1'l paftern-bone, is thrown upon the coffin and navi¬
cular bones. Of this weight the coffin bone receives
the greater {hare ; but the navicular-bone receives a
confiderable portion of it, though this bone does not
contribute to prevent concuflion fo much as Mr Freeman
has endeavoured to prove. The navicular-bone, when
the hoof touches the ground, defeends a little, and thus
prevents that concuflion which the horfe’s body would
have received if this bone had been immoveably fixed ;
and when the hoof is again raifed from the ground, the
elafticitv of the parts below the navicular-bone lifts up
this bone into its former pofition, thus aCling as a fpring
iti facilitating the motion of the animal. As the
weight fupported by the navicular-bone of the hind
feet h lefs than that fupported by the fame bone of the
fore feet, their defeent in the former is lefs than in the
latter. The organs connefted with the navicular-bone
t0 of the hind feet are alfo lefs fubjeCt to difeafe.
Coffin-bone- The coffin-bone (4, fig- Tj, Ms M-) is fo
from its being concealed, or as it were buried within the
hoof. B is alf° fometimes called the foot-bone. On
its fore part it is rounded, having very nearly the fhape
of the external hoof. Its upper furface is flightly hol¬
lowed (m, m, fig. 13.) to receive the lower end of the
fffiaji paftern-bone, vvith the fore part of which it aiti-
I
I E R Y. Part II.
culates, as it does behind with the fore edge of the na- Anatomy
vicular-bone. At the back part the coffin-bone ends cfthe.
in two proceffes on each fide, the upper of which Horfe
are tipped vvith cartilage. At the upper part of the
front of the coffin-bone there is a final] protuberance,
(w, fig. 13.) extending upwards above the joint, and
ferving for the infertion of the tendon of the muf-
cles that extend the foot. Below this the coffin-bone
is extremely porous, for the pafTage of nerves and
blood vefleis j and towards the lower part in particular
there are about 13 holes, for the tranfiniffion of con-
fiderabie arteries, which go to fupply the fenfible foie.
At the heels and quarters the coffin-bone is ftill more
porous, and is fupplied with a greater number of ar-
terfi, but thefe are proportionally fmaller. The low¬
er furface of the heels of this bone is alfo very porous,
where it unites with the fenfible foie, but the reft of the
lower furface is generally fmooth. There are here two
hollow furfaces, which receive two correfponding
rounded parts of the fenfible foie. They are unequal,
the foremoft being the larger. Into the hollow on the
back part, the tendon of the flexor-mufcle is inferted.
(A, fig. 16.)
There are feven ligaments belonging to the coffin-L:iram°ntfc
joint, of which there are three pairs, and one fingle. &
The fir ft pair of ligaments take their origin from the
heels of the coffin-bone on each fide, and pafs obliquely
upwards as high as the middle, to which they are at¬
tached, and at which part of the fmall paftern-bone
(B, fig. 16.) they are blended with the fibres of the la¬
teral ligaments of the fmall paftern-joint. The fecond
pair of ligaments on each fide arife from the edge of
the coffin bone, near the heels, and pafs obliquely for¬
ward to be inferted into the middle of the fmall palfern-
bone (C, fig. 16.) near the attachment of the extenfor-
tendon. Tie third pair take their origin from the
lateral edges of the anterior procefs of the coffin-bone^
and are inferted into the edges of the cartilages. The
ufe of thefe ligaments is to unite the cartilages more
firmly to the coffin-bone. The extenfor-tendon being
inferted into the upper edge of the anterior procefs of
the coffin-bone, prevents the neceffity of a ligament
at this part. The fingle ligament of the coffin-bone is
connected with the pofterior and inferior concave fur¬
face of the coffin-bone, immediately above the infertion
of the flexor-tendon, and alfo with the lower edge of
the navicular-bone. Beiides this ligament there is ano¬
ther attached to the whole of the upper and back part
of the navicular-bone, by which means that bone is en¬
abled to fupport a greater (hare of the weight that refts
upon it. By means of thefe ligaments this important
joint is rendered very ftrong, while by the elafticity
of the cartilages, and the conflant fupply of lubricating
fluid within the joint, all the motions of the animal are
rendered fafe and eafy.
The fmall paftern-joint is alfo well fecured by means
of ligaments, and by the fheath of the flexor-tendon.
There are alfo ligaments proceeding from the fefamoid
hones, which enter the fheath of the flexor-tendon, and
are attached to the fmall pattern-joint (a, a, a, fig. 16.).
“ The weight which the fefamuid bones, by means
of ligaments fuftain, is very different in different horfes $
and bears no proportion to the bulk and weight of the
animal. The pattern joints of large horfes deftined for
flow motion, are conftruCled very differently from tbofe
of