A and P chapter 13b spinal nerves and reflexes Flashcards
what is a nerve?
a bundle of axons (both myelinated and unmyelinated) that is enclosed ina connective tissue sheath
whats the difference between nerve and neuron
nerve=organ
neuron=cell
what are the nodes of ranvier
exposed part of an axon that allows for saltatory conduction
which type of nerve bundle transmits peripheral to the CNS
sensory (affarent) nerves
which type of nerve bundle transmits from the CNS to peripheral
motor (efferent) nerves
what are mixed nerves
have both motor and sensory nerves
name the 4 types of nerves you can find in a mixed nerve
somatic efferent (motor)
somatic affarent (sensory)
autonomic efferent
autonomic afferent
what are ganglia and where are they found
cluster of neuron cell bodies in the PNS
why are there so many cell bodies in ganglia
protection in numbers and allows for connection between pathways
where do C1 to C7 nerves emerge
above the vertebae
where do C8 nerve emerge
between C7 and T1 (below C7)
where do nerves from T1 down emerge from
emerge below the vertebrae and so forth
what is spinal root?
where rootlets from spinal cord or ganglia merge
What is a ramus?
initial branches off a nerve
what is a dorsal root?
merges with posterior horn gray matter and has sensory fibers that form the dorsal root ganglia
what is a ventral root?
motor fibers from anterior horn gray matter to skeletal muscle and autonomic NS fibers
What anatomical features are special to T2-L1
communicating rami connecting the sympathetic chain ganglion to the spinal nerve
what virus remains in the posterior root ganglia for life and how can it spread to cause a continuing disease process
zoster virus/chickenpox. Can migrate to other layers of sensory nerves when immune system is compromised and causes shingles
what is the difference between a root and a rami?
a root connects the spinal nerve to the spinal cord and the rami do not connect to the spinal cord
what is a dermatome
cutaneus branch representation of a single spinal nerve; sensory branch of single spinal nerve that covers some strip of body and doesn’t overlap (completely anyway)
what does a dermatome of the trunk look like
transverse strips of mostly uniform width
If the arm dermatomes are affected, which nerves are in question
C5-T1
if the leg dermatomes are affected, which nerves are in question
lumbosacral nerves
what is a nerve plexus
group of nerves that serve a particular region
why isn’t there a thoracic plexus of nerves
we have sympathetic nervous system here
name the plexuses
cervical, brachial, lumbosacral (lumbar and sacral), and coccygeal
which important nerve is in the cervical plexus that has to do with breathing
phrenic nerve
what does the phrenic nerve innervate
diaphragm. If affected can stop breathing
which nerves are found in the brachial plexus
axillary, musculocutaneus, radial, median, and ulnar
what does the axillary nerve innervate
shoulder skin, deltoid, and teres minor
what does the musculotaneous nerve innervate
upper anterior arm, elbox flexors (biceps brachii, the brachioradialis, and the brachialis), and lateral skin
what does the radial nerve innervate
extensors of the entire upper limb (heads of the triceps), skin
what does the median nerve innervate
elbow, wrist, and thumb/finger flexors ( pronator teres, flexor carpi radialis, palmaris longus, and flexor digitorum superficialis), skin [innervates thumb and digits 2 and 3)
what does the ulnar nerve innervate
medial elbow, wrist, and finger flexors (flexor carpi ulnaris and flexor digitorum profundus. It also innervates the intrinsic muscles of the hand including the palmaris brevis) [innervates digits 5, 4, and 3]
which nerve is responsible for carpal tunnel
median nerve
which nerves are found in the lumbar plexus
genitofemoral, obturator, and femoral
what does the genitofemoral nerve innervate
the genitals
what does the obturator nerve innervate
the adductor longus, adductor brevis, and gracilis muscles, as well as giving innervation to the hip joint.
what does the femoral nerve innervate
quads, sartorius, pectineus, and iliacus along with skin of medial leg and foot and hip, knee joints
which nerves make up the sacral plexus
fibular, tibial, sciatic, pudendal
what does the fibular nerve innervate
the muscles of the anterior compartment of the leg; tibialis anterior, Extensor Digitorum Longus and extensor hallucis longus. These muscles act to dorsiflex the foot, and extend the digits. It also innervates some intrinsic muscles of the foot.
what does the tibial nerve innervate
the muscles of the lower leg and foot. Specifically: triceps surae (the two headed gastocnemius and soleus), plantaris, Popliteus, tibialis posterior, flexor digitorum longus and flexor hallucis longus. It also has articular and cutaneous branches.
what does the pudendal nerve innervate
innervates the external genitalia of both sexes and the skin around the anus, anal canal and perineum.
what two nerves make up the sciatic nerve
fibular and tibial
name the receptors classified by stimulus
mechanoreceptors–> mechanical change in tissue shape
thermoreceptors–> temperature
photoreceptors–> light energy
chemoreceptors–> chemicals in solution (smell, taste, etc.)
nociceptors–> pain
name the receptors classified by location
exteroceptors–> outside body stimulus
interoceptors–> inside body stimulus
proprioceptors–> monitor body movements in space
name the receptors classified by structural complexity
simple- general senses
complex- special senses
what is a relfex
rapid, predictable, involuntary, motor responses to stimuli
what is serial processing
the reflex itself
what is parallel processing
the part after a reflex where we understand what happened and what to do next
what are the components of a reflex arc
receptor
sensory neurons
integration center
motor neuron
effector
describe stretch reflex steps
stretch of extensor muscle–>sensory pathway–>excites extensor–>while also inhibiting the flexor=knee flexion for patellar reflex
describe the deep tendon reflex
inhibitory to rectus femoris-tells it to stop contracting + excitatory to biceps femoris- tells antagonist to contract as agonist relaxes= relax from patellar reflex
what is the crossed extensor reflex
withdrawal reflex+extension on opposite side
what are superficial reflexes
triggered by cutaneous stimulation
what are some examples of superficial reflexes
plantar reflex and abdominal reflex
describe the plantar reflex
checking to make sure L4-S2 nerves are okay
performed by stroking lateral side of plantar surface
if hallux dorsiflexes and the other digits fan out, then this is a positive babinski sign and it indicates damage
(there should just be plantar flexion if normal)
describe the abdominal reflex
checks T8-T12
when abdominal area stroke, umbilicus moves toward location of stimulus
name the 4 processes of pain
transduction
transmission
modulation
perception
describe transduction (pain)
graded potential
nociceptors convert painful stimuli into action potentials at the sensory receptor
describe transmission(pain)
usually action potentials
PNS to spinal cord
pain signals transmitted to the spinal cord in two types of unipolar sensory neurons (A delta fibers and C fibers)
what is the difference between A delta fibers and C fibers
A delta fibers are for sharp acute pain
C fibers are for chronic dull pain (more of these)
describe modulation (pain)
graded potentials or action potentials
pain perception initiates a decending pain inhibiting mechanism from brainstem to dorsal horn where natural opoids are released (endorphins and enkephalins)
describe perception (pain)
graded potentials in interneurons
neuron processing of pain (how we perceive it)
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