Limbic System, Cerebral Cortex, Neuroembryology

Question 1

reticular formation

Answer 1

• contrains the principal discharge pathways for the olfactory/limbic systems and the hypothalamus
• plays an important role as a mediator of somatic and visceral motor components of autonomic, emotional, and behavioral responses

Question 2

components of emotional expression:

Answer 2

• hippocampus: memory recall
• amygdala
• neocortex: modify rxn
• hypothalamus: effector of emotional behavior

Question 3

brainstem ascending reticular activating system

Answer 3

• glasgow coma scale
• level of consciousness
• drugs

-sends info to intralaminar reticular nuclei–>cortex (EEG and cognition) and prefrontal cortex (Broca’s, Prefrontal Lobe Syndrome)

Question 4

septal areas

Answer 4

• addiction
• behavior/misbehavior
• pleasure (+), punishing (-)
• drugs

Question 5

olfactory input

Answer 5

goes straight to septal areas and amygdala

Question 6

hypothalamic circuitry

Answer 6

• most of ascending input into the hypothalamus is from reticular formation
• most of descending influences are mediated by reticular formation

Question 7

lesions of hypothalamus

Answer 7

S/S:

• obesity
• personality changes
• diabetes insipidus
• temp maintenance problems
• hormonal problems

Question 8

Korsakoff’s Syndrome

Answer 8

• bilateral destruction of mammillary bodies and dorsal medial nucleus of thalamus
• may result from long term alcoholism or pituitary tumors
  
  • if pituitary tumor, may cause bitemporal hemianopsia
• primary deficit is impairment of recent memory
  
  • pts report confabulation to fill the gaps in their memory

Question 9

Paper Circuit

Answer 9

cortex–>entorhinal cortex of uncus–>hippocampus–>fornix–>mammillary body–>anterior nucleus of dorsal thalamus–>cingulate gyrus–>parahippocampus

olfactory input–>amygdala and hippocampus and septal area
-hippocampus and amygdala goes thru the stria terminalis to the septal area–>hypothalamus–>midbrain tegmentum

Question 10

medial forebrain bundle

Answer 10

-interconnects septal area, hypothalamus, and midbrain tegmentum

Question 11

primary olfactory cortex or pyriform lobe

Answer 11

• lateral olfactory gyrus
• amygdaloid nucleus and pariamygdaloid area
• entorhinal cortex: uncus and parahippocampus
  
  • connects sensory info going over the cerebral cortex and puts it into memory

Question 12

entorhinal cortex

Answer 12

• chief input into the hippocampus
• acts as a critical integrator and mediator of info to hippocampus
• cortical electrical impulses cascade over the surface in a spiral like pattern that converges on the entorhinal cortex
• important link in Paper memory circuit
• neocortical representation of external sensory world and a person’s memory seem to merge in entorhinal cortex

Question 13

amygdala

Answer 13

• fibers from olfactory tract and pyriform cortex terminate here
• convey emotional and motivational component of odors–pheromones
• pivotal processing center for olfactory, somatosensory, viscerosensory, and emotional expressions
  
  • relays info to the hypothalamus, dorsomedial thalamic nucleus, septal areas, or midbrain tegmentum

Question 14

amnesia

Answer 14

• refers to any defect in memory but most assoc with cases of severe and relatively isolated memory deficits like in Korsakoff’s
• anterograde–unable to learn new material
• retrograde–is an inability to recall events from recent past

Question 15

hippocampal amnesia

Answer 15

• bilateral lesions of hippocampus
• pts IQ and formal reasoning were normal but unable to master new facts, recognize new acquaintances, or adjust to new surroundings
• pyramidal cells of CA1 region of hippocampus are vulnerable to hypoxic or ischemic injury
  
  • axons form the fimbria-fornix pathway and send recurrent collaterals to entorhinal cortex

Question 16

olfactory hallucinations

Answer 16

• an imaginary, disagreeable odor, movements of lips and tongue, and dream state of consciousness
• sensations may be mildly pleasant or curious
• odors (hallucinations) may disturb the individual, and disrupt activities especially sleep

Question 17

uncal herniation

Answer 17

• any unilateral lesion that inc the hemispheric volume is likely to cause herniation of uncus thru IPSILATERAL central notch
• deficits:
  
  • compresses oculomotor N: pupillary dilation, external strabismus, and complete ptosis
  • compresses abducens N: gaze is down and in
  • compression of cerebral peduncle: pushes contralateral cerebral peduncle against shape edge of tentorium cerebella and spastic hemiplegia occurs on same side of ipsilateral lesion
  • compression of PCA: contralateral incongruous homonymous hemianopsia with macular sparing

Question 18

encephalization of sensory and motor system

Answer 18

sophisticated sensory and motor systems are dependent on cortical areas which could discriminate, analyze, interpret, and respond to specific stimuli
-upward shifting of fcns to cortex is encephalization

Question 19

language and the cerebral cortex

Answer 19

• derivative of neocortical evolution

- development of brain for reception, comprehension, and expression

Question 20

lateralization of cortex

Answer 20

• language underwent lateralization which was allowed by the corpus callous
  
  • specific fcn residing in one hemisphere yet still share its info with other side

Question 21

layers 1-2 of cerebral cortex

Answer 21

• form the most superficial layers of cortex
• layers play a role in important roles in assoc and higher cognitive fcns such as memory, interpretation of sensory input, and certain discriminative fcns

Question 22

layers 3-4 of cerebral cortex

Answer 22

• receive most of afferents into cortex
• only 1% of these afferents are thalamocortical fibers
  
  • remaining are corticocortical fibers

Question 23

layers 5-6 of cerebral cortex

Answer 23

-innermost layers of cortex of cortex are source of efferents from cortex such as assoc fibers, commissural fibers, and projection fibers

Question 24

superior longitudinal fasciculus (SLF)

Answer 24

• AKA arcuate fasciculus
• interconnects frontal, parietal, and occipital lobes
• critical link for language association areas
• lesions result in conduction aphasia
  
  • fluent with minor word finding pauses and paraphasia, and can’t repeat words or sentences
  • comprehension and reading ability intact but writing has errors

Question 25

cingulum

Answer 25

-interconnects septal area, cingulate, parrahippocampal gyro to entorhinal cortex

Question 26

uncinate fasciculus

Answer 26

interconnects base of assoc areas of frontal lobe to inferior temporal lobe

Question 27

genu of internal capsule

Answer 27

- fibers: corticobulbar fibers | - lesion: supra nuclear facial palsy

Question 28

posterior limb of internal capsule

Answer 28

- fibers: corticospinal fibers - lesion: contralateral spastic hemiplegia - fibers: somesthetic fibers - lesion: contralateral hemianesthesia

Question 29

retrolenticular of internal capsule

Answer 29

putamen and globus pallidus - fibers: optic radiations - lesion: contralateral homonymous hemianopsia

Question 30

Brock's Aphasia

Answer 30

- nonfluent speech - full comprehension - right sided paralysis

Question 31

Wernicke's Syndrome

Answer 31

- fluent and paraphasic speech - no comprehension - slight or no right sided paralysis

Question 32

3 month fetus and growth of SC

Answer 32

-spinal cord extends throughout the entire length of vertebral column

Question 33

5 month fetus and growth of SC

Answer 33

- vertical column has grown longer than the SC | - conus medullaris is at the level of first sacral vertebra

Question 34

neonate and growth of SC

Answer 34

-conus medullaris is at the level of 3rd lumbar vertebrae

Question 35

adult and growth of SC

Answer 35

- conus medullaris at level of LV1-2 interspace - nerve roots coursing in lumbar cistern below level of conus medullaris are lengthened due to this differential growth and will form caudal equina

Question 36

rachischisis

Answer 36

- vertebral column defect with exposure of primitive SC or Ns - failure of neuropore to close

Question 37

spina bifida occulta

Answer 37

- herniation of meninges or neural tissue - presents as cystic, midline, hairy mass in lumbar region of vertebral column - may be due to failure of the roof plate of neural tube to induce the development of overlying spinous processes

Question 38

spina bifida meningocele

Answer 38

-vertebral column defect with herniation of meninges

Question 39

spina bifida meningomyelocele

Answer 39

-vertebral column defect with herniation of meninges, SC

Question 40

hydrocephalus

Answer 40

- congenital stenosis of portion of ventricular system or certain fetal infections - assoc with meningomyelocele

Question 41

Arnold Chiari malformation

Answer 41

- common cerebellar anomaly - almost always with meningomyelocele - involve an elongation of the cerebellar vermis, which herniates thru foramen magnum - syringomyelia may also occur

Question 42

anencephaly

Answer 42

- involve cranial or cervical rachischisis--meroanencephaly | - means absence of brain but pt usually has brainstem

Question 43

meningoencephalocele

Answer 43

- cranial defect with herniation of meninges and brain tissue - most infants with with have Arnold Chiari malformation - also have hydrocephalus

Question 44

meningocele

Answer 44

cranial defect with herniation of meninges

Question 45

meningohydroencephalocele

Answer 45

-cranial defect with herniation of meninges, brain, ventricles

Question 46

cranial rachischisis

Answer 46

- congenital absence of forebrain usually with cranial defect of frontal and parietal bones - due to failure of neural tube to close