40 
MAMMALIAN ANATOMY 
median dorsal spinous process, two lateral transverse processes, 
two anterior articular processes, and two posterior articular 
processes. 
Note in a lateral view of the two adjacent vertebrae, that the 
anterior vertebral notch of one and the posterior vertebral notch 
of the other form together the intervertebral foramen. 
Articulations. —Note carefully the boundaries of articular 
surfaces. The body articulates with the bodies of adjoining 
vertebrae; the arch articulates with their arches by means of the 
articular processes; each transverse process bears a costal pit 
for the tubercle of the rib, and the body bears costal pits for the 
heads of the rib (tubercular and capitular articulations respec¬ 
tively); note that in the middle thoracic region, the capitular 
articulations are divided between adjoining bodies; note also 
the absence of tubercular articulations in the case of the more 
posterior thoracic vertebras, owing to the reduction of the tuber¬ 
cles of the corresponding ribs. 
(. b ) A Pair of Ribs Corresponding to the Thoracic Vertebra 
Studied. 
Orientation and identification as right or left. 
Parts. —Body, angle, tubercle, neck, head. 
Articulations.- —Tubercle with transverse process of vertebra, 
and head with body of vertebra (or with the two bodies of adja¬ 
cent vertebras); ventrally either directly or indirectly with the 
sternum through the costal cartilage (except the two floating ribs). 
(c) The Sternum. 
Note the division into the manubrium, body, and xiphoid 
process. Identify the articular surfaces for the clavicles, and for 
each pair of ribs. 
To show the relationships of the parts of a typical thoracic seg¬ 
ment, draw either an anterior or posterior view of a thoracic vertebra, 
the corresponding ribs, and a diagrammatic representation of the 
cross section of the sternum, all natural size, the bones slightly sepa¬ 
rated to show their complete form. Draw also a dorsal view of the 
vertebra, a lateral view of the vertebra, together with the adjacent 
anterior one, and a ventral view of the sternum, showing all the rib 
articulations . 
