Neuro Midterm Practical

what is gray matter composed of? what does it form?

• brain (outer) → cell bodies + dendrites (pink-gray due to blood supply)

• forms nuclei (specialized w/ functionally related cell bodies) + cortex (layered surface covering CNS)

what is white matter composed of? tract?

• brain (center) → axons (w/ myelin sheath), fatty + white

  • fasciculus, funiculus, lemniscus, peduncle

• tract → specialized axon bundle w/ common origin + destination

what are the sulci that divide 6 lobes in each cerebral hemisphere?

• central → frontal vs parietal

• lateral → fronto-parietal vs temporal

• parietooccipital → parietal vs occipital

• cingulate → parietal vs limbic

what are the cortical regions of the frontal lobe?

• primary motor (precentral gyrus) → contains cell bodies of desc. path + initiates voluntary movement

• premotor + supp. motor (precentral + post frontal gyri) → planning + initiate voluntary movement

• motor speech (broca) → opercular + triangular inf. frontal gyrus (L. hemisphere)

• prefrontal → executive fxn, personality, insight/foresight

what are the components of the parietal lobe?

• postcentral gyrus (primary somatosensory cortex) → tactile + proprioception (sensory localization)

• inf. parietal lobe (L. hemisphere) → language comp. (w/ temporal)

• remaining → spatial orientation + attention direction

what are the components of the temporal lobe?

• primary auditory cortex (sup. + small area of sup. gyrus) → process auditory info

• sensory speech (wernicke) → post. portion of sup. gyrus (L. hemisphere)

• visual info. process (inf. surface) → higher-order visual processing

• learn + memory (med) → complex learning + memory

occipital lobe, limbic lobe, insula function and location?

• occipital → visual fxn, primary visual cortex (calcarine sulcus + surrounding cortex)

• limbic → emotional response, drive-related behavior + memory formation (w/ hippocampus)

• insula → sensory + emotional processing, covered by opercula

diencephalon function? divisions?

• sensory processing, homeostasis, regulate various physiological fxn w/in brain

• thalamus, hypothalamus, subthalamus

thalamus function? hypothalamus function?

• thalamus → every path conveying subcortical info to cerebral cortex stops here (except olfactory)

• hypothalamus → control autonomic fxn (visceral response, temp. reg., limbic system)

which nerves emerge from midbrain? cerebral peduncle function?

• CN III (oculomotor) + CN IV (trochlear)

• cerebral peduncles carry desc. projection from cerebral cortex

which cranial nerves emerge from basal pons? middle cerebellar peduncle function?

• CN V (trigeminal) lat., CN VI (abducens) midline, CN VII (facial) + CN VIII (vestibulocochlear) cerebellopontine angle

• middle cerebellar peduncle carries input to brain

which structures does the medulla contain?

• pyramids → carry fibers destined for spinal cord

• olive → protuberance post. to pyramids

  • CN XII (hypoglossal) emerge from pyramid-olive sulcus

cerebellum function? lobes?

• coordinate movement + maintain balance

• ant. (ant. to primary fissure) → coordinate trunk + limb movement

• flocculonodular → receive input from vestibular system, control eye movement + posture

• post. → largest, receives most cortical input, coordinate voluntary movement, balance/control, timing/precision

location of basal nuclei/ganglia? function?

• neuronal cell body masses beneath cerebral cortex in each hemisphere

• motor control + other

  • caudate nucleus → C shape, frontal to temporal

  • lenticular nucleus → putamen + globus pallidus, lat. + partial ant. to thalamus

what is the internal capsule of the basal nuclei/ganglia?

• white matter, thick fiber sheet separating lenticular nucleus from thalamus + caudate nucleus

• contains fibers interconnecting cerebral cortex, thalamus, caudate nucleus

function of amygdala and hippocampus?

• emotional processing, memory formation, spatial navigation w/in limbic system

• amygdala → emotional processing + memory

• hippocampus → memory formation + spatial navigation

when does the notochord form? what does it initiate? what does it turn into?

• first

• initiates neural tube formation (via SHH)

• induction of ectoderm → neural plate

• becomes nucleus pulposus (IV disc)

what does the neural tube give rise to? what is produced after the neural tube fuses? what are the 3 dilations?

• CNS (brain + spinal cord)

• neural tube fuses → roof plate makes BMP + floor plate makes SHH

• primary brain vesicle

  • prosencephalon

  • mesencephalon

  • rhombencephalon

what does the prosencephalon (forebrain) form? what forms the ventricles?

• telencephalon → cerebral hemispheres (hippocampus, basal ganglia, olfactory cortex

  • vesicles → lateral ventricles (btwn lat. + 3rd = interventricular foramen of Monro)

• diencephalon → hypothalamus, thalamus, pineal gland, neurohypophysis, retina

  • cavity = 3rd ventricle

what does the mesencephalon (midbrain) form?

• ant. (visual) + post. (auditory) colliculi

• cavity = cerebral aqueduct (of sylvius) → connects 3rd + 4th ventricles

what does the rhombencephalon (hindbrain) form? what occurs if there is failure of the rhombic lips to form properly?

• metencephalon → pons + cerebellum

  • failure to dev. → greatest effect on motor fxn

• myelencephalon → medulla oblongata

• cavity = 4th ventricle

• failure of rhombic lips to form = coordination problems

what does the cavity of the spinal cord become? what occurs after the neural tube closes?

• central canal

• neural tube close → neuroepithelial cells divide (3 layers)

  • ventricular, intermediate, marginal

what does ventricular zone (neuroepithelial layer) give rise to?

• layer of ependymal cells lining central canal

• primitive nerve cells (neuroblasts) → all neurons + glial cells of spinal cord

what does the intermediate zone (mantle layer) consist of? what originates from here?

• neurons + glial cells of gray matter (spinal cord)

• contains developing alar plate + basal plate

  • basal plate → hypoglossal nerve + nucleus ambiguus

what does the marginal zone contain? what does it form?

• nerve fibers (axons) of neuroblasts of mantle layer + glial cells

• forms white matter of spinal cord thru myelination of axons

what forms after neuroblasts are added to the mantle layer (intermediate zone)?

• ventral thickenings (basal plates) → ventral motor horn cells, motor areas

• dorsal thickenings (alar plates) → form sensory areas

where does the conus medularis extend to? where do nerves exit?

• @ birth → L3, @ adult → term. L1-L2

• lumbar, sacral, coccygeal nerves “pulled up” relative to IV foramina they exit from (disc herniation effect)

what do they centricles contain?

• initially → amniotic fluid

• later → choroid plexus develops w/in = CSF

what do neural crest cells give rise to? if migration fails? what does each spinal nerve and ganglion associate with?

• PNS (peripheral nerves + enteric ganglia)

• failure of migration → greatest impact on myelination in PNS

• w. somite of developing embryo

non neural derivatives of neural crest cells? what can disruption in neural crest cells cause?

• aortic arch, pharyngeal arch, adrenal medulla, chromaffin cells, melanocytes, schwann cells

• disruption in neural crest cells → syndromes affecting face, heart, metabolism, nervous system

  • e.g: cleft lip/palate, treacher collins, tetralogy of Fallot albinism, pyloric stenosis, Hirschsprung disease

when does the neural plate fold? what does it give rise to? what do some cells differentiate into?

• wk 4 → lat. edges elevate to form folds (fuse = neural tube)

• cranial = brain, caudal = spinal cord, lumen = ventricular system of brain + central canal of spinal cord

• some cells diff. into neural crest cells

what do the basal plate and alar plate in the brainstem give rise to?

• basal → motor cranial nerve nuclei

• alar → sensory cranial nerve nuclei

what are neural tube defects (NTD)? what can detect early NTD? what can prevent it? what can it present as?

• failure of ant. or post. neuropore to close → congenital defect

• elevated a-feto protein in amniotic fluid

• folic acid

• open defect in lumbar area

what is holoprosencephaly (HPE)? characteristics? mild characteristic?

• loss of midline structure = malformation of brain + face

• sulci + gyri absent

  • some mild cases → presence of single central incisor

what is anencephaly? characteristics?

• upper NTD via failure of cranial/ant. neuropore of neural tube fusing during wk 4

• failure of brain to fully develop (rudimentary brain present) + failure of bony cranial skull to form

  • incompatible with extrauterine life (survive only few hours)

what is spina bifida occulta? how is it “hidden”? when does it occur? characteristics? how can it be prevented?

• vertebral arches fail to form properly → create vertebral defect in lumbosacral region

  • most common + mild form (involves 1+ vertebrae)

• wk 3-8

• tuft of hair + dimple over lower lumbar region

• folic acid

if the anterior and posterior neuropore doesn’t close during wk 4 what NTD conditions could occur?

• meningocele → meninges protrude thru vertebral defect + form CSF filled sac

• meningomyelocele → meninges/spinal cord protrude + form CSF filled sac

• rachischisis (myeloschisis) → post. neuropore of neural tube fails to fuse

what is hydrocephalus? what obstruction causes this? what does it impact?

• abnormal accumulation of CSF in 3rd ventricle

• obstruction of aqueduct of Sylvius (aqueductal stenosis) → prevents CSF of lat. + 3rd ventricle from passing into 4th ventricle + subarachnoid space (usually resorbed)

• impacts midbrain (cerebral aqueduct)

what is arnold-chiari malformation? symptoms?

• caudal herniation of cerebellar vermis/tonsils + medulla oblongata thru foramen magnum

• symptoms → movement abnormalities, abnormal eye movements, motor + sensory deficit

  • compress medulla + CNIX, CNX, CNXII → difficulty swallowing, vibration during respiration (laryngeal stridor), diminished gag reflex, hoarseness