Nervous system Flashcards
What are the three lobes in your primitive prototype brain?
How do they split into the 5 main mature lobes?
Prosencephalon (forebrain) mesencephalon (midbrain) rhombencephalon (hindbrain). Prosen splits into telencephalon which is your cerebral cortex, and diencephalon which is thalamus + hypothalamus. Mesencephalon stays the same as the midbrain and rhomb splits into meta (cerebellum) and myelin (medulla).
Walk me through the divisions of the nervous system, starting with CNS and PNS
CNS is made up of the brain and the spinal chord, PNS is made up of all the nerves that come off of it. Can be divided into afferent (sensory) and motor (efferent). Motor can be somatic (voluntary) or autonomic. ANS can be sympathetic (fight or flight) or parasympathetic (rest and digest)
What do we call a collection of nerve cell bodies outside of the CNS
A ganglion !
Four defined regions of every neuron and its function
Dendrites - receive messages from neighbouring neurons
Cell body - house nucleus, mitochondria etc for cell
axon- transmits messages
synaptic terminal - passes messages onto other neurons
Walk me through the events at a chemical synapse
An action potential reaches the synaptic terminal which triggers voltage gated calcium channels to open. This influx of calcium channels forces the vesicles to fuse to the membrane and release their neurotransmitter. The NT diffuses across the cleft and binds to receptors on dendrites / cell bodies, triggering a response in the neighbouring neuron. NT is either reabsorbed or recycled unless acted upon by drugs (SSRI etc)
Neuroanatomical orientation above the midbrain diencephalic junction? Below it?
Above: Dorsal (top), caudal (back), ventral (bottom), rostral (front)
Below: Dorsal (back), caudal (bottom), ventral (front), rostral (top)
List the three planes of axis and what view they give
Saggital plane down the medial line - gives right and left
coronal / frontal plane horizontally - gives front and back
transverse - gives top and bottom
What is the most common excitatory NT in the CNS? Most common inhibitory?
Glutamate and GABA
What is Myasthenia Gravis
An autoimmune disorder where a loss of neuromuscular transmission from destruction of Ach receptors prevents nerve impulses from triggering a muscular contraction. Most commonly affects eyes, face, and swallowing
NT involved in executive functions, motor control, motivation, arousal, reinforcement, and reward…..
Dopamine !
Agonist is cocaine
Antagonist is antipsychotics, reduces dopamine output
Explain the four dopaminergic pathways
- Mesolimbic - VTA to NA, schizo has too much here
- Mesocortical - VTA to cortex, schizo has to little here
- Nigrastriatal- Substantia nigra to striatum
- Tuberoinfudibular - hypothalamus to pituitary gland
What causes Parkinson’s disease
reduced dopamine output from substantia nigra onto the striatum
What NT does the sympathetic post ganglion release? Some functions?
Norepinephrine
In the brain - it increases arousal, alertness, memory retrieval, focus
Body - releases glucose from storage, increases HR, reduces blood to GI
Which cells produce myelin in CNS and PNS?
Oligo in CNS, multiple neurons at once, no nodes of ranvier
Schwann in PNS - one part of axon at once, nodes of ranvier
Name for the end of the spinal chord at L1/L2?
Name for nerve roots after this?
Conus medullaris and cauda equina
Function of the thalamus
Relay station for sensory and other inputs into the cortex (synapse here), acts as a selective filter and information processor
General functions of frontal lobe, temporal lobe, occipital lobe, and parietal lobe.
Frontal lobe - motor, production of speech (broca), problem solving, planning, emotions, judgement, impulse control i.e higher order functions
Parietal lobe - sensation
temporal- speech comprehension, auditory information, memory
occipital - visual processing
Two primary visual cortex pathways ?
Dorsal - parieto occipital - where
Ventral - occipital temporal - what
Three types of white matter pathways within the brain?
Projection fibres, association fibres, commissural fibres
Axons of projection fibres are gathered into a small bundle called the _____ and above this they spread out to form the _____
Internal capsule, corona radiata
What do commissural fibres do?
Connect alike areas in the right and left hemisphere i.e corpus collosum
What causes Guillan Barre syndrome
Autoimmune destruction of Schwann cells in the PNS. Usually after an infection or surgery, lose muscle strength in the periphery.
For blood supply to the brain, which arteries ascend anterior vs posterior ?
Anterior we have the carotid arteries coming off the aorta and subclavian (internal goes through carotid canal)
Posterior we have vertebral arteries coming off subclavian (Forman magnum)
Where is the carotid sinus and what does it do
Bulge in the internal carotid right after bifurcation at level of C3/4. Houses sensory baro recptors that project to the medulla and sense changes in blood pressure
Label the Circle of Willis Diagram in your head !
Vertebral arteries have anterior spinal artery coming off posterior and posterior inferior cerebellar artery laterally (PICA). Two vertebral become basilar which then has the anterior inferior cerebellar artery (AICA), the pontine arteries, superior cerebellar artery, and then becomes the posterior cerebral artery. This connects to the posterior communicating arteries which extend to the internal carotid / middle cerebral artery. Anterior to this is the anterior communicating artery and the anterior cerebral artery.
Where do the ACA, MCA, and PCA supply blood to in the brain
Anterior cerebral artery - medial and inferior sides of the frontal / parietal lobe
Middle cerebral artery - lateral of frontal / parietal / temporal lobe
Posterior cerebral artery - occipital lobe
List the meninges in order of superficial to deep. What are the two layers of dura matter?
Dura (periosteal then meningeal), arachnoid, Pia matter
What do arachnoid granulation villi do
They are projections from the arachnoid matter into the dura matter that allow drainage of CSF into the sinuses
Separation between dura matter periosteal and meningeal layer around cerebral hemispheres is called ____ and around cerebellum is called _______
Falx cerebri and tentorium cerebelli
Where do dural sinuses eventually empty into. What fluid should be in here
The jugular vein - blood and CSF
What are the three possible locations for hematoma in the brain?
Epidural space, subdural space, subarachnoid space
What does red blood cells in an arachnoid tap indicate?
Subarachnoid hemmorage, should only be CSF here
CSF is produced by a specialized vascular structure called ____
Choroid plexus found in lateral and fourth ventricles
How does the lateral ventricles communicate with third ventricle ? How does 3rd communicate with fourth?
Foramen of monro, cerebral aqueduct
3 main symptoms of normal pressure hydrocephalus aka water on the brain
cognitive impairment, gait disturbance, urinary incontinence
Gait will be magnetic, start and turn hesitation, normal arm swing
How many spinal segments do we have? Whats the breakdown of them?
31 - 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, 1 coccygeal
What kind of information is located in the dorsal horn? Ventral horn?
Dorsal - sensory information
Ventral - motor neurons (LMN)
What level is the lumbar cistern for spinal taps or epidurals ?
L3 or L4
Where is the denticulate ligament?
In the spine, attaches the Pia matter to the dura matter to add stability for the spinal cord
Two distinct components of the intervertebral discs?
Nucleus polyposis and annulus fibrosis
What key muscles are innervated by the C5 nerve?
What about the L2 nerve?
Elbow flexors & hip flexors
What is the Jendrassik manevour and what does it show?
If we clench our jaw and interlock our fists, we can increase the excitability / reflex to a stretch stimulus (hammer on knee). This happens because usually the UMN would modulate and inhibit some of the reflex but it can’t when being used.
What are the six locations for a deep tendon reflex produced as a result of muscle spindles reacting to a change in length
C6 Biceps, C7/8 Triceps, L3 patellar, S1 Achilles, L5 medial hamstrings, L1 lateral hamstrings
What is radiculopathy ?
Sensory or motor dysfunction due to pathology of the spinal nerve
What causes cauda equine syndrome?
central disc herniation below level of L1
What are the two major somatosensory pathways in the spinal cord and what do they do?
Dorsal column medical leminscus (fasiculus gracilis and cuneatous) - conscious proprioception and discriminative touch
Spinothalamic tract - temperature, pain, crude touch
When do the spinothalamic tract’s second order neurons cross over (sensory is contralateral)
Right away, at the level that they come into the SC
When does the second order neurons of the DCML cross over midline?
At the medulla, where they synapse with the nucleus gracilis or cuneatous
Signs of UMN lesion vs LMN lesion ?
UMN - muscle weakness, hyper reflexes, increased tone
LMN - muscle weakness, atrophy, fasciculation’s, hypo reflexes, fatiguability with repetition, decreased tone
Two divisions of the main descending pathway in SC?
Lateral corticospinal tract and medial corticospinal tract
What is a group of axons in a nerve called?
Fascicles
What is Wallerian degeneration?
A breakdown of nerve fibre distal to the injury site
Which glial cell producing myelin can regenerate and which cannot
PNS Schwann cells can help an axon regenerate but Oligo in the CNS cannot
Why is the ANS nervous system slower acting than the somatic
Uses two neurons instead of one and the post ganglionic axon is always unmyelinated
What are the descending fibre tracts from the cerebral cortex in the midbrain called (stalks)
Cerebral peduncles
