Module 3: Peripheral Nervous System Flashcards
what is the PNS?
everything outside of the CNS (brain and spinal cord)
how many pairs of spinal nerves are there?
31 pairs
how many cranial nerves are there?
12 pairs
what is the composition of the PNS?
- 31 pairs of spinal nerves
- ganglia
- enteric plexuses (GIT)
- other nerve plexuses
- sensory receptors
what do afferent nerves do?
carry information from sensory receptors to the CNS
what are afferent nerves?
somatic: skin, muscle, joint, reflexes and visceral organs (feeling full)
what do efferent nerves do?
carry information AWAY from CNS to effector organs
what are efferent nerves?
- somatic, innervate skeletal muscle
- autonomic, innervates smooth muscle, caridac muscle and glands (parasympathetic and sympathetic)
what is the sympathetic nervous system?
fight or flight - increases metabolic rate
what are the 5 features of the sympathetic nervous system?
- sight of origin: thoracolumnar (thoracic start, lumbar finish) shorter than parasympathetic
- preganglia shorter than parasympathetic
- have pre and post ganglions
- postganglia larger than parasympathetic
- ganglions are close to spinal cord
what is the parasympathetic nervous system?
rest and digest - decreases metabolic rate
what are the 4 features of the parasympathetic nervous system?
- sight of origin: cranialsacral (cranium start, sacral finish) - longer than sympathetic
- postganglia is shorter than sympathetic
- preganglia is longer then sympathetic
- ganglions are close to visceral organs
what are the 2 types of nerves in the PNS?
- spinal: arise from the spinal cord
- cranial: arise from the brain
how are the nerves of the PNS classified?
based on impulse direction
1. sensory (dorsal, towards CNS)
2. motor (ventral, away CNS)
3. mixed (both directions)
what are the 3 connective tissues protecting the nerves?
- epineurium
- perineurium
3.endoneurium
where is the epineruim in the nerve?
outermost connective tissue layer around nerve, epi means upon
where is the perinerium in the nerve?
middle connective tissue layer around nerves, peri means around
where is the endoneurium in the nerves?
innermost connective tissue layer around nerves, endo means within
why do nerves have blood vessels?
nerves need a lot of energy to function
how are the 31 spinal nerves distributed?
8 cervical nerves
12 thoraccic nerves
5 lumbar nerves
5 sacral nerves
1 coccygeal nerves
how many pairs of cranial nerves are there?
12 pairs
what does the vagus nerve do?
longest nerve of the body and works for the organs
what is a ramus?
a branch off of a nerve
what is the function of the dorsal ramus?
- mixed spinal nerve
- sensory and motor innervation to skin and back muscles
- smaller than ventral ramus
what is the function of the ventral ramus?
- mixed spinal nerves
- sensory and motor innervation to the rest of the trunk and limbs
- larger than dorsal ramus
what is a nerve plexus?
multiple spinal nerves interacting together to perform a function
why is there several nerves working together to form a plexus?
if 1 nerve is broken or damaged complete loss of function doesn’t occur
what are the 4 main plexuses?
- cervical: under sternocleidomastoid (sternum-skull) muscle: innervates skin
- brachial: neck, shoulder: innervates upper limbs
- lumbar:innervates psoas muscle (attached to lumber spine-femur): innervates ab wall, anterior and medial thigh
- sacral: posterior lumbar plexus: innervates lower limbs, buttox and pelvis
what is the composition of the brachial plexus?
5 roots
3 trunks
3 cords
5 peripheral nerves
what are the 5 peripheral nerves in the arm?
- musculocutaneous nerve
- axillary nerve
- radial nerve
- median nerve
- ulnar nerve
what happens if you damage the brachial plexus?
- pins and needles
- funny bone tingles
- carpal tunnel
- weakened grip
- paralysis
- babies born can have damage called plexus birth palsy 3-6 month recovery, may need surgery to stitch back together
where does cranial nerve 1 attach to?
the cerebrum - olfactory
where does the cranial nerve 2 attache to?
the diencephalon - optic
where do the cranial nerves 3-12 attach to?
the brain stem, so everything else