PRACTICAL DIRECTIONS. 459 
2. The superior vena cava (p. 316). Find its branches. ‘Trace 
the azygos as far back as the diaphragm without dissecting it at all. 
Find the division of the innominate (p. 318) into subclavian and 
external jugular. 
Trace next— 
3. The external jugular (p. 319). Remove the skin from the 
side of the face and trace its branches (Fig. 131). The internal 
jugular, vena facialis profunda, the sttbmentalis, and the deep 
terminal branches of the posterior facial cannot be followed at this 
time; veins shown on Fig. 131 should all be found, however. 
4. Trace the thyrocervical axis and its branches (p. 293). Add 
them to your diagram of the subclavian. 
5. Follow the common carotid artery (p. 283) and internal 
jugular vein (p. 320). Find the division of the common carotid into 
its terminal branches and then dissect its lateral branches and those 
of the internal jugular (see Fig. 119). 
6. The external carotid (p. 285, and Fig. 119). Follow its 
branches with the exception of the internal maxillary. 
7. The internal maxillary (p. 287). Find its inferior alveolar 
branch first and follow it by cutting away with bone-forceps the ven- 
tral border of the lower jaw. To follow its other branches and those 
of the carotid plexus, remove the zygomatic arch, cut the temporal, 
masseter, and pterygoid muscles, and cut the mandible behind the 
incisor teeth and remove it. The branches which pass into the 
skull are not to be followed at present. The posterior facial vein 
(p. 323), the vena facialis profunda (p. 323), and the submental vein 
(p- 323) may be followed at the same time. 
8. The internal carotid (p. 285). Follow it to the point where 
it enters the cranium. 
g. Trace the other branches of the costocervical axis (p. 292). 
To do this, cut the arteries and nerves of the axilla on the side on 
which they have been dissected, allowing the arm to fall backward. 
Then trace the branches of the costocervical axis with tracer, scalpel, 
and bone-forceps, taking care not to injure the vertebral artery. 
Add these branches to your diagram of the subclavian. 
10. The vertebral artery (p. 291). Trace it to the foramen 
transversarium of the sixth cervical vertebra. Then with bone-forceps 
follow it to the atlas and into the atlantal foramen. Add this to 
your diagram of the subclavian. 
11. The basilar artery (p. 291) and the other arteries of the 
brain (p. 289) are best studied on a preparation, similar to that 
shown in Fig. 121. To obtain such a preparation it is only neces- 
sary to remove the brain (for directions, see p. 462) of a specimen 
in which the arteries have been injected. 
(12. Veins of the brain and dura mater (p. 324). These can be 
worked out only with much difficulty, except on specimens injected 
with gelatine. The skull must be chipped away and the veins 
followed without destroying them.) 
