anatomy of the nervous system 2 Flashcards
what does the peripheral nervous system consist of?
cranial nerves (12 pairs) and spinal nerves (31 pairs)
what does the lateral horn consist of?
autonomic fibres
describe the spinal tracts of white matter
- ascending tracts — carry info to the brain from the periphery (sensory)
- descending tracts — carry info from the brain to the periphery (motor)
spinothalamic tracts
- lateral and ventral
- spine —> thalamus —> cortex
name 2 dorsal columns (ascending tracts)
fasiculus gracilis — lower limb
fasciculus cuneatus — upper limb
what is a fasciculus?
bundle of fibres
describe the sensory pathway
lateral vs ventral spinothalamic tract
lateral — pain and temperature
ventral — touch and pressure
where does the 3rd order neuron go to in the spinothalamic tract?
homonculus
describe the dorsal columns
where are the corticospinal tracts?
lateral — at back
ventral — by fissure
describe the somatic motor pathway?
- only 2 neurons
- most cross in medulla
- upper motor neurone states in precentral gyrus
ventral vs lateral corticospinal tract
ventral stays ipsilateral at medulla then crosses, lateral crosses
what are located in the brainstem?
sensory nucleus and motor nuclei
how many nerves are there in a cranial pathway?
3
what synapses on the sensory nuclei in the brain stem?
2nd order neurone
where are the nerve cell bodies of CN V, CN VII, and CN IX & X?
in the PERIPHERY
CN V = trigeminal ganglion
CN VII = geniculate ganglion
CN IX & X = superior and inferior ganglia
where is the nerve cell body of the 2nd order neurone in the general sensory pathways of cranial nerves?
trigeminal sensory nucleus of brainstem (regardless of cranial nerve). fibres decussate here
ganglion vs nucleus
ganglion = collection of NCB outside CNS
nucleus = collection of NCB in CNS
where is the NCB of the 3rd order neuron in the general sensory pathways of cranial nerves? where do axons project?
- NCB in VP thalamus
- axons project to primary sensory cortex
what are the 3 subnuclei of the trigeminal sensory nucleus?
- mesencephalic = in midbrain. proprioception
- chief sensory nucleus = touch and pressure
- spinal nucleus = pain and temperature
from the trigeminal sensory nucelus, ______ fibres go the the _____ nucleus of the _____
trigeminothalamic fibres go to the ventral posterior nucleus of the thalamus
some nerves in the corticobulbar tract are bilaterally innervated. what is the exception?
hypoglossal nerve CN XII
which nerves are bilaterally innervated?
- oculomotor, CN III
- trochlear, CN IV
- trigeminal, CN V
- abducens, CN VI
- glossopharyngeal, CN IX
- vagus, CN X
- accessory, CN XI
how is the facial nerve different?
- the facial motor nucleus is made up of 2 parts
- superior part supplies muscles on upper half of the face — superior half is bilaterally innervated
- inferior part supplies the muscles on lower half of the face — inferior part is contralaterally innervated
what would be the effect of an UMN lesion in the facial nerve?
- superior parts of both sides of face still supplied
- lower part not supplied of contralateral side to lesion — droopy face
what 2 types of receptors are used in the parasympathetic nervous system? neurotransmitter?
what 2 types of receptors are used in the sympathetic nervous system? neurotransmitter?
how are postganglionic SYMPATHETIC neurones acting on sweat glands different?
release ACh which binds to muscarinic receptors
label
where are nerve cell bodies of preganglionic neurones located?
lateral horn of grey matter
describe the route of the axon of preganglionic neurons?
axons passes in ventral root —> spinal nerve —> ventral rami —> white ramus communicantes
then takes 1 of 3 options
at what level is sympathetic outflow?
T1-L2
what are the 3 options of the sympathetic preganglionic neurons?
- synapses in paravertebral ganglion at own spinal level
- passes up/down the chain to synapse in cervical or pelvic paravertebral ganglion
- passes straight through chain to synapse in prevertebral ganglion
if the preganglionic sympathetic neuron passes straight through the chain to synapse in a prevertebral ganglion, what is the preganglionic neuron called? where does the postganglionic neuron pass to?
splanchnic nerve
post ganglionic neuron passes directly to the effector organ
