186 
ANATOMY OF THE HORSE. 
Form .—Flat, thick, an extended triangle, presenting its base 
towards the spine. 
Attachment .—Superiorly, to the spinous processes of the dor¬ 
sal vertebrae, and to the ligamentum colli (vel potius, dorsi ) 
investing them ; stretching as far forwards as the highest point 
in the withers, and as far backwards as the lumbar spines, to 
some of which it is also connected : inferiorly, to the inner and 
upper part of the body of the humerus. 
Relations. — Superiorly, with the trapezius, rhomboideus bre¬ 
vis and posterior angle of the scapula; inferiorly, with the triceps 
extensor brachii: externally, with the panniculus; internally, 
with the ribs and serratus magnus. 
Direction .—Oblique: downwards and forwards; the fibres 
converging in their course. 
Structure .—Superior part, a broad and extended aponeurosis; 
inferiorly, it ends in a long, flattened, thin tendon : the interme¬ 
diate parts are entirely fleshy. 
Action. —To flex the humerus, by drawing it backwards and 
elevating its inferior extremity. 
rhomboideus brevis .— Dorso-subscapularis. 
Situation .—Upon the side of the withers : deeply seated. 
Form .—Flat and square. Thin, superiorly; thick, inferiorly. 
Attachment .—Superiorly, to the four or five anterior dorsal 
spinous processes, and to the ligament clothing their summits: 
inferiorly, to the inner part of the superior costa of the scapula 
and the cartilage surmounting it. 
Relations. —Externally, with the trapezius and cartilage of the 
scapula; internally, with the vertebrae and ribs : anteriorly, it is 
connected with the rhomboideus longus; posteriorly, it is crossed 
by the latissimus dorsi. 
Structure .—Fleshy : enveloped in a cellular expansion. 
Action .—To elevate the scapula. 
2.—PECTORAL REGION. 
These muscles form the breast , or what is vulgarly and ab¬ 
surdly called the bosom . 
PECTORALIS TRANSVERSUS.— 
Situation .—Lateral, anterior, and inferior parts of the breast. 
The pair form the fleshy prominences seen directly from the front. 
Form. —An approach to a triangle whose apex has been cut 
off*: broad and thick, superiorly; narrow, inferiorly. 
f Sterno-aponeuroticus. 
\ Sterno-humeralis. 
