Neuro A&P review - lec 1

What are the layers of a neural tube?

What are the layers of a neural tube?

• marginal (outer): develop to white matter

• mantle (middle): develop to gray matter

• ependymal (inner): lines brain ventricles and central canal of cord; CSF

Prosencephalon is _____

forebrain

Telencephalon is ______

cerebrum and basal ganglia

Diencephalon is ______

thalamus and hypothalamus

Mesencephalon is ______

midbrain

Rhombencephalon is _____

hindbrain

Metencephalon is ______

pons and cerebellum

Myelencephalon is ______

medulla and spinal cord

_____ develops from the neural tube (brain, spinal cord)

CNS

_____ develops from neural crest (all neural structures outside cord)

PNS

What prevents risk of defects of neural tube closure and can prevent spina bifida?

folic acid (400 mcg QD)

How long after conception does the neural tube close?

18-26 days

Which cells are only supportive, without electrical excitability, and can’t multiply?

glial cells

Which cells are large, single axon, electrically excitable, post mitotic and non dividing?

neurons

Which type of glial cell is the most abundant, attaches to nerves + blood vessels anchoring neurons to capillaries, involved in ion (K+) transfer and is an integral part of the BBB?

astrocytes / spider cells

Which type of glial cells wrap around axons in the CNS to form myelin sheath, providing insulation and enhancing electrical impulses?

oligodendrocytes

which type of glial cells are mobile throughout the CNS and function as macrophages and perform phagocytosis (immune system)?

microglia

Which type of glial cells line ventricles and canal of the spinal cord, secreting CSF?

ependymal cells

Which type of glial cells wrap around axons in the PNS forming myelin sheath and have phagocytic activity?

Schwann cells

What connects the left and right cerebral hemispheres, enabling messages to be delivered between the two halves?

corpus callous

What is the 5th lobe of the brain called?

insula

Which lobe is responsible for behavior, emotions, problem solving, planning & attention, and contains primary motor region on the pre central gyrus?

frontal lobe

Which lobe is responsible for speech, language and hearing decoding, short term memory, identification of smell?

temporal lobe

A tumor in which lobe of the brain would cause olfactory hallucinations?

temporal lobe

Which lobe of the brain is responsible for touch, and contains the primary sensory region on the post central gyrus?

parietal lobe

A lesion in which are of the brain would cause sensory deficits of astereognosis, hemispatial neglect, and inability to copy figures?

parietal lobe

Precentral gyrus is the primary ______ region; postcentral gyrus is the primary ______ region

motor ; sensory

Which lobe is responsible for visual processing, shape and color identification?

occipital lobe

Which area of the brain coordinates motor activity such as starting, stopping, and monitoring the intensity of movements?

Basal Ganglia

A lesion in which area of the brain would cause movement disorders, tremors and other extrapyramidal syndromes (EPS)?

basal ganglia

What clinical syndrome of the basal ganglia is from loss of dopaminergic neurons in the substantial nigra & is associated w/ rigidity, bradykinesia, tremors and loss of postural reflexes?

Parkinsonism

What clinical syndrome of the basal ganglia is associated with damage to the contralateral subthalamic nucleus of Luys?

Hemiballismus (hemichorea)

What clinical syndrome of the basal ganglia is a hereditary disease of progressive dementia and chorea, associated w/ atrophy of the caudate nucleus?

Huntington’s chorea

What area of the brain?

• major sensory relay & translates impulses related to pain, attention, and alertness (all sensory input except olfactory)

• has profound influence on cognitive function and motor via input from basal ganglia and cerebellum

thalamus

what area of the brain?

• integral part of endocrine system controlling pituitary functions

• master control for ANS aiding in blood glucose levels, HR and RR during stress, temperature, hunger, thirst, sleep-wake cycle, etc

hypothalamus

What are the functions of the limbic cortex?

emotion (amygdala + cingulate gyrus) and memory (hippocampus)

Which area of the brain arises from vestibular nuclei, maintaining control over balance and coordination?

cerebellum

Proprioceptors from limbs and trunk go to which area of cerebellum?

anterior lobe

Messages from cerebrum, motor cortex, and corticospinal tract go to which area of cerebellum?

posterior lobe

what is toxic to the cerebellum, poisoning the vestibulocerebellar neurons?

alcohol

What are the three regions of the brain stem?

midbrain, pons, medulla oblongata

Which area of the brain?

• conduction pathway b/t higher and lower brain centers

• visual and auditory reflex centers (superior/inferior colliculi)

• subcortical motor centers (substantial nigra and red nuclei)

• contains nuclei for CN III and IV

midbrain

Which area of the brain?

• conduction pathway b/t higher and lower brain centers

• respiratory nuclei (work w/ medullary resp centers) to control resp rate and depth

• contains nuclei for CN V-VII

pons

Which area of the brain?

• conduction pathway b/t higher brain centers and spinal cord

• site of decussation of pyramidal tracts

• nuclei of CN VIII-XII

• contains nuclei cuneatus and gracilis

• contains visceral nuclei controlling HR, RR, vessel diameter, vomiting, coughing

medulla oblongata

How far does the spinal cord extend?

from medulla to 1st or 2nd lumbar vertebra

What are the sensory pathways of the spinal cord?

spinothalamic tracts and dorsum columns (medial lemniscus pathway)

what are motor pathways of the spinal cord?

corticospinal tracts

Which roots travel the longest, fanning out like a horse tail forming the cauda equina?

lumbar and sacral

DTRs are ______

monosynaptic

How do DTRs work?

tap tendon → activates sensory fibers in partially stretched muscle → triggers sensory impulse that travels from peripheral nerve to spinal cord → sensory fiber synapses w/ anterior horn cells → impulse crosses NMJ → muscle contraction

Descending or ascending tracts?

• motor pathways

• pyramidal / direct / corticospinal

• extrapyramidal / indirect

descending

Descending or ascending?

• sensory pathways

• dorsal column- medial lemniscal pathways

• anterolateral / spinothalamic

• spinocerebellar pathways

ascending

What tract is pain and temperature?

lateral spinothalamic tract

What is the pain and temperature neural pathway?

1st neuron: sensory receptor to dorsal horn

2nd neuron: dorsal horn to lateral spinothalamic tract to thalamus

3rd motor neuron: thalamus to brain

A lesion on the RIGHT side at T5 will lose pain and temperature sensation where?

CONTRAlateral and BELOW

(Left side @T5 and below)

What tract is associated with light touch and pressure?

Anterior spinothalamic tract

What is the light touch and pressure neural pathway?

1st order neuron: sensory receptor to dorsal horn

2nd order neuron: dorsal horn to ant. Spinothalamic tract to the thalamus

3rd order neuron: thalamus to the brain

Discriminative touch, vibration and proprioception are what tract?

Dorsal white column

(Fascicles cuneatus and gracilis)

What is the vibration/proprioception/discriminative touch neural pathway?

1st order neuron: sensory neuron to dorsal white column to the medulla

2nd order neuron: medulla to thalamus

3rd order neuron: thalamus to brain

Where does vibratory sense/proprioception/discriminative touch synapse?

medulla (I/L)

Where does pain/temp / light touch / pressure synapse?

spinal cord (C/L)

____ neurons are involved for sensory function; ______ neurons are involved for motor function

3 ; 2

where do corticospinal tracts (motor) crossover?

lower medulla

where do the UMN and LMN synapse?

anterior gray horn

A lesion on the RIGHT side of T5 will lose vibratory sense where?

IPSILATERAL and BELOW the lesion

RIGHT side and below T5

Which motor pathway provides control of voluntary movements with neurons passing through medullary pyramids?

pyramidal motor pathways

Which motor pathway provides automatic/involuntary control and coordination through the cerebellum and basal ganglia?

extrapyramidal motor pathways

Motor neurons that connect the cerebral cortex to the spinal cord are ____

upper motor neurons

Motor neurons that connect the spinal cord to the target muscle are ______

lower motor neurons

Motor pathway damage to UMN?

• bulk- normal til disuse atrophy

• tone- inc (except in spinal shock → flaccid + recovers in 2 wks)

• power- dec; tends towards normal over time if adequate stimulation maintained

• fasciculations NOT commonly seen

• reflexes- brisk

• plantar/babinski- up going

Motor pathway damage to LMN?

• bulk- prominent weakness and atrophy early

• tone- always hypotonia!

• power- severely dec

• fasciculation d/t degenerative process

• reflexes- dec or absent

• plantar/babinski- downgoing

Where does the arterial supply to the brain come from?

bilateral internal carotid and bilateral vertebral arteries

which artery feeds the trunk, legs, feet, and genitals?

anterior cerebral artery

Which artery feeds the hands, arms, face, and tongue?

middle cerebral artery

Protection of the brain from out to in?

Scalp

Connective tissue

Aponeurosis

Loose connective tissue

Periosteum (bone of cranium)

What membranes protect the CNS?

meninges

• dura mater: outer layer

• arachnoid mater: lies above subarachnoid space

• pia mater: delicate inner layer directly covers brain

Blood between the inner surface of the skull and the dura is known as _______

epidural hematoma / arterial blood

Blood between the dura and arachnoid is known as _______

subdural hematoma / venous blood

blood below the arachnoid (& above Pia) is known as _____

subarachnoid hemorrhage

How should CSF appear?

clear, colorless, few cells, and little protein

Which system has SHORT preganglionic neurons that release ACh and LONG postganglionic neurons that release NE?

sympathetic

Which system has LONG preganglionic neurons and SHORT postganglionic neurons that both release ACh?

parasympathetic

SNS regulates ________

glands, smooth muscle, cardiac muscle

Parasympathetic nervous system regulates ______

sexual arousal, salivation, lacrimation, urination, digestion, defecation

Epi/NE is with _______ ; ACh is with ______

SNS ; ANS

What neurotransmitter affects cholinergic receptors (nicotinic & muscarinic), has fewer receptors on the brain, is the primary neurotransmitter of the PNS and has a role in arousal, attention, and motivation?

Ach

What syndrome arises when drugs blocks Ach in the CNS and PNS?

• blind as a bat (dilated pupils)

• red as a beet (vasodilation/flushing)

• hot as a hare (hyperthermia)

• dry as a bone (dry skin)

• mad as a hatter (hallucinations/agitation)

• bloated as a toad (ileum, urinary retention)

• heart runs alone (tachy)

anticholinergic syndrome

What are the glutamate receptors?

NMDA and non-NMDA (AMPA)

The main stimulatory neurotransmitter is ______

glutamate

What neurotransmitter is believed to contribute to pathogenesis of Alzheimers through overstimulation, is associated with excitotoxicity, and has been implicated in epileptic seizures?

Glutamate

The most addictive drugs increase what neurotransmitter activity?

dopamine

What neurotransmitter?

• secreted from substantia nigra

• selective inhibitor (reduce muscle contraction)

• produces arousal

• involved in executive function, motor control, motivation, reinforcement and reward, lactation, sexual gratification, and nausea

• L-DOPA precursor synthesized in brain and kidney

Dopamine

What would happen if there is damage to the substantia nigra?

loss of dopamine secreting neurons → not enough dopamine → too much inhibition of spontaneous movement (cog wheel rigidity, not smooth) → parkinsons

What is the treatment for parkinsons?

L-DOPA (bc it can cross BBB)

administer w/ carbidopa to prevent conversion to dopamine before crossing BBB

Schizophrenia is thought to be due to overstimulation of what receptors in the cerebral cortex?

dopamine / D2 (tx w/ dopamine antagonists)

What neurotransmitter?

• synthesized from tryptophan

  • levels controlled by uptake of tryptophan and intraneuronal MAO

• controls appetite, sleep, mood, behavior, muscle contraction, endocrine regulation

• contributes to feelings of well being and happiness

serotonin

A decrease of what neurotransmitter would cause migraine HAs by allowing for dilation of blood vessels in the brain?

serotonin

Which neurotransmitter influences anxiety and impulsive behavior, causing some patients w/ low levels to attempt suicide by dramatic means?

serotonin

The main inhibitor neurotransmitter is ______

GABA

Which neurotransmitter has been implicated in seizures?

Both GABA and Glutamate