STUDY OF THE SPINAL CORD 
67 
muscles and viscera; and the communicating ramus between each 
spinal nerve and the corresponding ganglion of the sympathetic 
trunk. Draw. 
Examine other demonstration preparations made by dissecting 
from the ventral side. In making these it is necessary to remove 
much of the ventral musculature, and to lay open the thoracic, 
abdominal and pelvic cavities and remove most of the contained 
viscera, as well as the dorsal portion of the parietal serous mem¬ 
branes. The following are the more important structures to be 
seen: 
The course of the vagus nerve (and its accompanying sympa¬ 
thetic trunk), from its ganglion, which is located immediately 
posterior to the jugular foramen, through the whole length of the 
neck and the thoracic cavity, where it gives off branches to heart 
and lungs, and then continues through the diaphragm to the 
surface of the stomach where it enters into the formation of a 
plexus. 
The phrenic nerve which arises from a plexus formed by the 
ventral rami of the cervical nerves, and proceeds through the 
thoracic cavity passing over the surface of the heart to innervate 
the diaphragm. 
The brachial plexus formed from the ventral rami of the last 
three cervical and the first thoracic nerves, and located in the 
region between the anterior portion of the thoracic wall and the 
axilla. Follow ulnar, median, and radial nerves into the forearm 
and hand, noting the presence of both cutaneous and muscular 
branches. 
The lumbosacral plexus formed from the ventral rami of the 
posterior lumbar and anterior sacral nerves, and located in the 
dorsal wall of the pelvic cavity. Among its many branches may 
be distinguished the femoral branch which passes under the ingui¬ 
nal ligament to the medial side of .the thigh, and the very large 
sciatic branch which bends about the greater sciatic notch and 
passes to the back of the leg dividing in the lower leg into medial 
and lateral popliteal branches. Note the presence of both 
muscular and cutaneous branches. 
The delicate sympathetic trunk located upon each side of the 
mid-line back of the serous membrane in the dorsal wall of the 
