ANATOMY OF THE HORSE. 
243 
Figure .—Flattened ; conoid : bases turned downwards. 
Attachment .—Superiorly, to the transverse processes of the 
dorsal vertebrae : inferiorly, to the anterior borders of the ribs, in 
the spaces between their tubercles and angles. 
Relations .—Externally, with the longissimus dorsi; internally, 
with the ribs. 
Direction .—Oblique: from before backwards, and from above 
dowmvards. 
Structure .—Consisting of bundles of fleshy and tendinous 
fibres, having a similar arrangement to, and looking like the 
heads or beginnings of, the external intercostals. Their superior 
ends are interw r oven with small compact tendons, whence proceed 
tendinous slips, which intersect their fleshy bellies. Their inferior 
parts are enveloped in aponeuroses, which become thin and va¬ 
nish in proceeding upon their surfaces. The middle bundles are 
thickest and longest: the anterior ones are but scanty; and the 
three or four foremost ribs are entirely destitute of them. 
Action .—To assist in the elevation of the ribs. 
6.—DORSAL REGION. 
Including muscles connected with the vertebrae of the back. 
longissimus dorsi. — Ilio-spinalis. 
Situation .—Upon the supero-lateral parts of the back and loins. 
Figure .—Broad, thick, and elongated. 
Attachment .—Posteriorly, to the crista of the ileum, to the 
side of the sacrum, to the spinous and transverse processes of all 
the lumbar vertebrae, and to the spinous processes of the six pos¬ 
terior dorsal : anteriorly, to the angles of the twelve posterior 
ribs, to the transverse processes of all the dorsal vertebrae, and to 
those of the three or four hindermost cervical. 
Relations. —Externally and inferiorly, with the superficialis cos- 
tarum; internally, with the ribs and vertebrae; superiorly, with 
the spinalis dorsi. 
Direction . — Longitudinal; inclining downwards, as w r ell as 
forwards. 
Situation. —This muscle (which is one of the longest and, at the 
same time, most bulky muscles in the body) is constituted of a 
dense and strong aponeurosis; a thick, long, and uniform fleshy 
belly; and several broad and flat tendons intimately connected 
with the fleshy parts. The aponeurosis completely invests the 
lumbar portion of the fleshy belly; with the fibres of which it is 
so intimately adherent, that they are inseparable by the knife 
from one another ; from w r hich the aponeurosis is continued up¬ 
wards, to be fixed to the spines of the vertebrae ; and forwards, 
to be spread over the dorsal division of the muscle, upon which 
