2.4 Spinal Nerves Flashcards
What is a nerve?
consists of hundreds of thousands of axons wrapped in connective tissue
Where are nerves found?
PNS
What are ganglia?
collections of cell bodies in the PNS
How many pairs of spinal nerves are there?
31 pairs
Where do spinal nerves originate?
spinal cord
How many pairs of cervical nerves are there?
eight
How many pairs of thoracic nerves are there?
twelve
How many pairs of lumbar nerves are there?
five
How many pairs of sacral nerves are there?
five
How many pairs of coccygeal nerves are there?
one
How do spinal nerves leave the spinal cord?
roots
What does the dorsal root contain?
axons of afferent sensory neuronswhich conduct impulses to the cord
What does the ventral root contain?
axons of efferent motor neurons which conduct impulses away from the cord
Where do the ventral and dorsal roots join
just before the spinal nerve leaves the vertebral column
What do spinal nerves immediately divide into once they leave the vertebral column?
dorsal ramus
ventral ramus
What is the dorsal ramus?
contains nerves that serve the dorsal portions of the trunk carrying visceral motor, somatic motor, and sensory information to and from the skin and muscles of the back
What is the ventral ramus?
contains nerves that serve the remaining ventral parts of the trunk and the upper and lower limbs carrying visceral motor, somatic motor, and sensory information to and from the body surface, body wall, and limbs
What is a nerve plexus?
network of interconnecting nerves
What do nerves that emerge from a plexus contain?
fibers from various spinal nerves which are carried together to some target location
What are the major plexi?
cervical
brachial
lumbar
sacral
