Sympathetic Nervous System

In the fifth week, cells originating in the neural crest of the thoracic region migrate on each side of the spinal cord toward the region immediately behind the dorsal aorta (Fig. 19.42). Here they form a bilateral chain of segmentally arranged sympathetic ganglia interconnected by longitudinal nerve fibers. Together they form the sympathetic chains on each side of the vertebral column. From their position in the thorax, neuroblasts migrate toward the cervical and lumbosacral regions, extending the sympathetic chains to their full length. Although initially the ganglia are arranged segmentally, this arrangement is later obscured, particularly in the cervical region, by fusion of the ganglia.

Some sympathetic neuroblasts migrate in front of the aorta to form preaortic ganglia, such as the celiac and mesenteric ganglia. Other sympathetic cells migrate to the heart, lungs, and gastrointestinal tract, where they give rise to sympathetic organ plexuses (Fig. 19.42).

Was this article helpful?

0 0
Emergency Panic Remedies

Emergency Panic Remedies

Eliminate Your Panic And Anxiety Attacks Instantly With These Proven Techniques! There’s
 very
 little
 in
 this 
world
 that 
is
 as 
frightening
 and
 uncomfortable
 as 
a panic
 attack. 

Once
 they
 start,
 panic
 attacks
 can
 send
 you
 spiraling
 out
 of control.

Get My Free Ebook


Post a comment