768 
ANATOMY AND PATHOLOGY 
Jugular incisurex 
Sternal angle 
-Manubrium 
Costal incisure- 
Costal cartilage 
Body 4^ 
'Costo-chondral junction 
Xiphoid process 
Figure 1. — Ventral (anterior) view of skeleton of ovine thorax. 
ture. The thoracic inlet in spite of its narrow 
transverse diameter (5.1 cm mean diameter 
in adult sheep )i and slightly larger ventrodorsal 
diameter must transmit the same structures 
that pass in and out of the superior thoracic 
aperature of man, namely arteries, veins, auto- 
nomic and sensory nerve fibers, thymus, lym- 
phatics, esophagus and trachea. A small thoracic 
inlet in sheep therefore may seriously com- 
promise the use of this animal in the evaluation 
