ANATOMY OF THE HOUSE. 
109 
basis of which is cut obliquely, from above downward and from 
behind forward ; the point of the apex cut off perpendicularly ; 
the axis running in a direction from the front backward and 
downward. 
Dimensions. The antero-posterior diameter is the greatest. 
As we approach the apex the perpendicular more and more ex¬ 
ceeds the lateral measurement; towards the basis, in conse¬ 
quence of the sides diverging, these two diameters become 
about equal. 
Division. Into two surfaces and two circumferences. 
Exterior' Surface —Presenting, anteriorly, the projection of 
the cariniform cartilage of the sternum, with its sharp edge 
turned downwards, affording attachment to the pectoral mus¬ 
cles ; laterally, the convexities of the costal arches and their 
cartilages, and between them the intercostal spaces filled by the 
intercostal muscles ; superiorly, the dorsal spines, transverse 
processes, and vertebral grooves ; inferiorly, the sharpened lower 
border of the sternum, terminated by the xiphoid cartilage. 
Interior Surface —Formed, below, by the incurvation of the 
sternum and xiphoid cartilage; on the sides, by the smooth 
concavities of the ribs together with their cartilages ; above 
and along the middle, by the angular, smooth, descending por¬ 
tions of the bodies of the dorsal vertebrae ; above and along either 
side, by an oblong fossa formed by the angles of the ribs, into 
which are received the superior thick borders of the lungs. 
Anterior Circunference —Perpendicularly semi-oval, the small 
end turned dow nw ard ; bounded by the first dorsal vertebra, the 
first pair of ribs, and the sternum; making a passage for the 
trachea, esophagus, longus colli, carotid arteries, jugular veins, 
vertebral arteries and veins, axillary arteries and veins, par 
vagum, sympathetic and recurrent nerves, and thoracic duct. 
Posterior Circunference —Wide, but most extensive from 
above in the antero-inferior direction : bounded bv the last dorsal 
vertebra, the ensiform cartilage, the two last ribs, and the false 
cartilages ; affording attachment to the abdominal muscles, but 
more particularly to the diaphragm, by wdiich the intervening 
space is occupied. 
III.—THE PELVIS, 
Forms the posterior boundary of the trunk; is connected 
with the spine, and supported by the femoral bones ; presents a 
large, irregular cavity, open before and behind, in which are con¬ 
tained part of the intestines, and the urinary and genital or¬ 
gans ; and is composed of four bones :—the sacrum and os coc- 
cygis, and the two ossa innominata. 
