Neurophys 5-6 Flashcards
Somatic motor pathways
Control skeletal muscle
Visceral motor pathways
Control GIT, glands etc
Telencephalon
Cerebrum
Diencephalon
Thalamus, hypothalamus
Mesencephalon
Midbrain
Metencephalon
Cerebellum & pons
Myelencephalon
Medulla oblongata
Motor areas
Prefrontal cortex - planning
Premotor cortex - coordination
Frontal eye field - control of eye movement
Motor cortex - sit of upper motor neuron cell bodies
Motor cortex
Post cruciate gyrus - pelvic, thoracic limb
Rostrum suprasylvian gyrus - eyelid, ear, masseter, temporalis muscles, lateral cervical muscles
pyramidal decussation
Site where axon in lateral corticospinal tract crossing midline
Located in caudal medulla
Corticospinal tracts
Composed of upper motor neurons
Cell bodies in motor cortex
Axons descending through white matter of brain
Synapse Lower motor neuron in ventral grey matter of spinal cord
Neurotransmitter = glutamate
All axons cross to other side - cross over pyramid region of medulla (lateral corticospinal tract)
Lateral corticospinal tracts function
Voluntary control of skeletal muscle in distal limbs
Upper motor neuron - cell body in primary motor cortex
Axon crosses midline in the ventral medulla
Axon descends in the lateral corticospinal tract
Synapses on lower motor neuron in ventral horn
Extrapyramidal system functions
Other pathways synapse on upper and lower motor neurons
Functions:
Control postural reflex
Control of head and eye movement
Regulation of muscle tone
Alternative motor pathway
Basal nuclei function
Initiation movement selection of motor response eye movement motivation
Reticular formation function
Web group of interconnected nuclei in brain stem
Regulating alertness and consciousness
Norepinephrine, acetylcholine, serotonin
Vestibular nuclei
Input from inner ear
Info abt position & acceleration
Transmitter = glutamate
Vestibular ataxia
Cerebellum function & organization
Motor coordination
Hemispheres and vermis
Grey matter & white matter
- granular - purkinje - molecular
Connected to brain stem by white matter tracts
Input sensors of cerebellum
Vestibular nerve & nuclei - detect movement
Spinocerebellar tracts - detect body position
Motor cortex - movement info
UMN LMN synapse
Neurotransmitter = glutamate
Ionotropic receptors
Results = EPSP
Lower motor neuron function & location cranial nerves
Transmits signals to CNS to effector organ
Somatic = skeletal, directly Innervation
Ventral horn of spinal cord
- cell bodies in brain nuclei (cranial nerves)
Alpha motor neurons
Located in ventral grey matter of spinal cord
Inputs excitatory from upper MN (glutamate)
Inhibitory from Interneurons (GABA)
Modulators from extrapyramidal system
Output - axon synapses on skeletal muscle cells
Releases acetylcholine, causes contraction
Upper motor neuron disease
Results in paralysis or paresis
Spasticity
Lower motor neuron disease
Paralysis
Flaccidity
Pyramidal tract section
Paresis
Flaccidity
Motor unit
One alpha motor neuron + all innervated muscle fibers
Fine motor control, strength, each muscle fiber is innervated by just 1 motor neuron
Motor pool
Groups of motor neurons that innervate all the fibers in a single muscle
MN extends over several spinal cord segments
Motor spinal nerves
Cell bodies in ventral horn
Spinal nerve branches combine to innervate specific muscles
Structure of peripheral nerves
Axon - myelinated or unmyelinated
Connective tissue - endometrium, around individual axons
Perineurium - around bundles of axons
Epineurium - around nerves
Schwann cells - myelinates axons
NMJ
Synapse between a motor neuron and a muscle cell
Somatic NS
Neurotransmitter = acetylcholine
Receptors - nicotinic cholinergic
= channel opens & Na+ flows into cell = depolarization
Ca released in to Endo ret = muscle contraction
Cranial nerves vs spinal nerves
Cranial - have either Motor or sensory
Spinal - always have both sensory & motor
Nerves w sensory nerves
Olfactory, optic, trigeminal, facial, vestibulocochlear, glossopharyngeal, vagus
Nerves with motor function
Occulomotor, trochlear, trigeminal, abducent, facial, glossopharyngeal, vagus, spinal accessory, hypoglossal
Nerves with both motor and sensory
Trigeminal, facial, glossopharyngeal, vagus
Origin of cranial nerve III, IV, VI
Occulomotor, trochlear, abducent
Mesencephalon, myelencephalon
Origin of cranial nerve V
Trigeminal
Metencephalon (3 branches)
Origin of cranial nerve VII
Facial
Myelencephalon
Origin of cranial nerve IX
Glossopharyngeal
Myelencephalon
Origin of cranial nerve X
Vagus
Myelencephalon
Origin of cranial nerve XI
Spinal accessory
Myelencephalon
Origin of cranial nerve XII
Hypoglossal
Myelencephalon
Out put of cerebellum
Motor cortex via thalamus - limb & body movement
Cranial nerve motor nuclei - head & eye movement
Neurotransmitters of cerebellum
Trans : purkinje cells - GABA
Neurons in cerebellar nuclei release glutamine
Location and function of lower motor neurons - spinal nerves
Ventral grey matter of spinal cord (spinal nerves)
Axons - in spinal or cranial nerves
Axon terminal - synapses w muscle or gland cell
Alpha motor neurons - input & output
Inputs excitatory from upper MN (glutamate)
Output - axon synapses on skeletal muscle cells
Alpha motor neurons - inhibition and modulation
Inhibitory from Interneurons (GABA)
Modulators from extrapyramidal system
Neurotransmitters released by alpha motor neurons
Releases acetylcholine, causes contraction
location of corticospinal neurons
Composed of upper motor neurons
Cell bodies in motor cortex
Axons descending through white matter of brain
Reactions of corticospinal neurons
Synapse Lower motor neuron in ventral grey matter of spinal cord
Neurotransmitter = glutamate
All axons cross to other side - cross over pyramid region of medulla (lateral corticospinal tract)
lateral corticospinal tracts axon
Axon crosses midline in the ventral medulla
Axon descends in the lateral corticospinal tract
Lateral corticospinal tracts neurons
Upper motor neuron - cell body in primary motor cortex
Synapses on lower motor neuron in ventral horn
