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Neuro Exam 1
Terms in this set (130)
what is the CNS?
brain + spinal cord, enclosed in bone (skull and vertebral column)
what is the PNS?
Nerves (spinal and cranial nerves) that extend from CNS to body tissue
What is the Foramen Magnus?
hole in the base of the skull that shows where the brain ends and the spinal cord begins
Grey matter consists of?
White matter consists of?
How is grey and white matter organized in the brain vs the spinal cord?
BRAIN: Grey matter is on the outer rim and white matter is inside; SPINAL CORD: white matter is on the outer rim and grey matter is inside
How does grey and white matter stain? Why?
Grey matter stains white while white matter stains grey. This is because the stains attaches to the myelin that surrounds the axons
What is ganglia?
Grey matter; Collection of nerve cells (cell bodies) found OUTSIDE of the CNS
*basal ganglia is a misnomer b/c it resides in the CNS
what is a nucleus?
Grey matter; collection of nerve cells (cell bodies) inside the CNS
what is a cortex?
Grey matter; collection of nerve cells arranged in layers around outer rim of brain (bark)
*difference from nucleus is the fact that it does not reside within
what is a tract?
White matter; collection of nerve fibers (axons) in the CNS
what is a fasiculus?
White matter; collection of nerve fibers (axons) in the CNS
*differs from a tract simply because of size (larger than a tract)
Contralateral means ________?
opposite sides of the body
Ipsilateral means _______?
same side of the body
What are characteristics of the human brain?
- less than 3 pounds
- 2% of body weight
- 20% of metabolic energy and is on full power ALL the time
What are the divisions of the brain
- Metencephalon (pons)
- Myelencephalon (medulla oblongata)
what are the components of the telencephalon
- neocortex (outer cortex, "bark")
- limbic cortex
- basal ganglia
Function of the Neocortex?
- complex higher order behavior
- fine manipulative and sensory skills (hands, tongue, oral apparatus)
what are possible cortical disorders associated with the neocortex?
what is aphasia?
cannot communicate by means of language
what is dysarthria?
cannot articulate speech/messed-up speech
what is agnosia?
cannot interpret sensations though sensory organs are intact
what is apraxia?
cannot make skilled movements though not paralyzed
the left hemisphere is responsible for ______?
language (95% of population because most people are right handed)
the right hemisphere is responsible for ______?
what are the components of the diencephalon?
- pineal gland
- hypothalamus (visceral brain)
what is the function of the thalamus?
- "relay station"; receives sensory information from all systems EXCEPT OLFACTION (goes directly from nose to cortex, bypassing thalamus)
- Sensorimotor coordination
what is the function of the pineal?
what is the function of the hypothalamus?
- temperature regulation
- water regulation
- sexual function and regulation
- endocrine regulation
- appetite and metabolic regulation
another name for the hypothalamus is _____?
what are the components of the brain stem?
- mesencephalon (mid brain)
- pons (metencephalon)
- myelencephalon (medulla oblongata)
what is the function of the mesencephalon?
- visual and auditory coordination (superior and inferior colliculi respectively, DORSALLY)
- motor pathways (cerebral peduncles, VENTRALLY)
what is the function of the pons?
bridge; fibers travel between two sides of the cerebellum and between cerebellum and neocortex
what is the function of the medula oblongata?
- heart rate
- vascular tone
what is the function of the cerebellum?
- fine movements
- motor learning
what are cerebellar disorders?
what is dysdiadochokinesia?
inability to perform rapid alternating movements
what is dysmetria?
past pointing (ex: trying to touch nose but pointing past it)
what is ataxia?
inability to walk well; wide based gait
what are the components of the vertebral column (in order)?
how many vertebrae are in the vertebral column?
what are the vertebrae of the vertebral column?
how many spinal nerves are in the spinal cord?
how many cranial nerves?
what are the spinal nerves of the spinal cord? how are they arranged?
*Nerves C1 - C7 emerge above the vertebra of same number. C8 emerges below C7.
All others emerge below the vertebra of the same number.
What is the caudal equina?
the spinal nerves that extend from the conus medullaris
what is the conus medullar is?
the terminal portion of the spinal cord (because the spinal cord is shorter than the vertebral column)
*spinal cord ends at the conus medlars at L1
*spinal tap is done at the lumbar cistern at the L5, S1 or L4, L5
what is the filum terminale?
extension of the pia mater that acts anchors the spinal cord
Sensory is Afferent, Motor is Efferent; Dorsal is Afferent, Ventral is Afferent
on our backs; entirely sensory in function; contain dorsal root ganglia
on our stomachs; entirely motor in function; the cell bodies lie in the ventral horn of the spinal cord
what is the dermatome?
Area of skin innervated by one DORSAL root (unbranched spinal nerve)
What is plexus? (and examples)
the joining of some spinal nerve branches to other spinal nerve branches. forms larger named nerves
ex: ulnar nerve, medial nerve, static nerve
what are the three meninges (and physical appearance)?
- dura mater (thick)
- subarachnoid (spidery)
- pia mater(thinnest)
what are the meningeal spaces (and location)?
- epidural space (separates the dura mater from and the skull/vertebrae column)
- subdural space (separates the dura mater from the subarachnoid)
- subarachnoid (separates the arachnoid from the pia mater)
what is the content of the meningeal spaces?
- epidural: fat and veins (only in the epidural space surrounding the spinal cord; the epidural surrounding the brain is EMPTY)
- subdural space: potential space- NOTHING THERE
- subarachnoid: cerebrospinal fluid, arteries, extended in places called cisterns
what are the extensions of the pia mater (and their functions)?
- denticulate ligaments: anchors the spinal cord within the dura mater
filum terminale: anchors the spinal cord
what are the four brain ventricles (and location)
- 2 lateral ventricles (within the neocortex- one in each hemisphere)
- third ventricle (located medially; b/w the two halves of the diencephalon)
- fourth ventricle (between cerebellum and the roof of the pons and medulla oblongata)
what are the connections of the ventricles and meningeal space?
- foramen of Monroe (medial): connects the lateral ventricles to the midline third ventricle
- cerebral aqueduct (aqueduct of sylvius): takes CSF from the third to the fourth ventricle
- formamen of magendie (medial) and two foramina of luschka (lateral): exit points from the fourth ventricle to the subarachnoid space
what forms CSF?
choroid plexus ependymal cells
what are the specialized structures that reabsorb CSF?
- arachnoid villae
- arachnoid granulations
- venous lacunae
*NOTE: only in the brain
describe the drainage of CSF process
Gravity pulls the CSF from the lateral ventrical third ventricle fourth ventricle (out through the foramen) subarachnoid space. And then.....
DESTINATION 1: Because of all the pressure of the CSF, it enters the subarachnoid space and then works its way back up to the brain to the top. (subarachnoid venous lacunae, arachnoid graulation, and arachnoid villae (which protrudes into the SSS and allows for diffusion) superior sagittal sinus blood (venous) heart. OR...
DESTINATION 2: it goes down to the subarachnoid space of the spinal cord.
For DESTINATION 1: the 4 reabsorption sites are listed above. These are sites where CSF rejoins the venous system/blood (YES THERE IS CSF IN THE BLOOD)
The superior sagittal sinus is an area where venous blood (blood destined for the heart) pools. ***CSF is produced constantly which is why it is important to have this drainage system, otherwise pressure would build up
what percent of our brain is utilized?
are individuals more commonly right brain dominate or left?
Most brain functions are localized to specific brain areas, but redundancies exist. Because of redundancies and cross-talk between brain hemispheres, the notion that we are either left- or right-brained thinkers is also a myth.
T or F: you can train your brain to gain mental flexibility
F- Brain-training can give a task-specific boost, but may not be transferrable.
What is Hebbian Plasticity?
- use it or lose it
- fire together, wire together
what is phrenology?
a pseudomedicine primarily focused on measurements of the human skull, based on the concept that the brain is the organ of the mind, and that certain brain areas have localized, specific functions or modules. BRAIN MYTH (rather we have localization of function)
relationship between the nervous system and congenital defects?
1/3 of all neonatal congenital birth defects
- 75% of spontaneous fetal deaths are rural related
- 40% of deaths in first year of life
what are causes of congenital malformation?
- genetic factors (genetic mutations)
- environmental factors
- combination of the two
another name for environmental insults is ________?
- time: specific
- stimulus: largely unknown
The effects of teratogens depend not only on the nature of the teratogenic agent, but also on the time during embryogenesis (time-specific). More than one teratogen causes the same developmental anomaly depending on the time of insult.
how many cells are in the body?
what are the three stages of human brain development?
- fetal period (3-8 weeks prenatal): period of organogenesis
- embryonic period (9 weeks prenatal-newborn): period of cellular proliferation
- maturation period (25 weeks prenatal- 4 years old): period of functional maturation of the neuron
*early stage occurs in the first two weeks prenatal
what part of the prenatal process is the most crucial for the CNS development?
first four months (period of time that CNS is most susceptible to teratogen influence)
3-8 weeks prenatal; organogenesis
what major developmental events occur in the embryonic period?
1. The formation of three germ layers (ectoderm, mesoderm, and endoderm)
2. The formation of notochord
3. the formation of the neural tube
4. Primary neuralation
Beginning of the 3rd week?
formation of the three germ layers (ectoderm, mesoderm, endoderm) from the bilaminar disc (which consisted of two layers- epiblast and hypoblast)
Process summary: The primitive streak appears on the anterior epiblast, marking the beginning of gastrulation. The cells in the epiblast begin to migrate to form the three germ layer
what is derived from the ectoderm layer?
what is derived from the mesoderm?
2) reproductive organs
5) vascular system
what is derived from the endoderm?
End of the 3rd week?
Process: longitudinal rod (notochord) forms from mesoderm bells soon after gastrulation is complete. The notochord and a region anterior to it, called the prechordal plate express bone morphogenic protein (BMP) inhibitors (noggin, chordin, and follistatin) and sonic hedgehog (SHH) which induce the overlying anterior ectoderm to thicken and form a longitudinal neural plate. Late in the third week, the neural plate develops the neural folds which have the effect of creating the neural groove which begins to close (to eventually form the neural tube). This is induced by the notochord.
what does the notochord later become?
the spinal/vertebral column
1) closure of the neural tube (fully forms): anterior neuropore closes at 24-26 days (primary neurulation) while posterior neuropore closes at 26-28 days (secondary neurulation)
2) induction of mesoderm-derived structures by the neural tube
3) dilation of the neural tube (which leads to the formation of 3 primary vesicles)
4) optic vesicles form
5) neural crest formation
6) demarcation of spinal cord
what does the anterior neuropore later become?
what does the neural tube later become?
CNS (brain and spinal cord); its cavity becomes the ventricular system of the brain
neural tube defects
*also called dysraphisms
1) anencephaly: (no forebrain; incompatible with life)
2) encephalocele/ cranium bifidum: anterior failure, severe retardation
3) spina bifida: posterior failure of neural tube development
Neural tube defects (dysraphisms) facts
1) Failure of the neural tube formation or closure
2) Failure of induction of certain mesodermal structures
3) 1/1000 live births
4) Diagnosis during pregnancy
- Elevated levels of alpha-fetoprotein
- Ultrasound examination
5) Folic acid deficit is now added to fortified grain products in the US. NOTE: Vitamin B9 (Folate) is needed for DNA synthesis. Folic acid play s a role in neural tube defect prevention
what are the types of spina bifida?
1) spina bifida occulta (most cases)
2) spina bifida cystica (three types: spina bifida w/ meningocele, spina bifida w/ meningomyelocele, and spina bifida w/ myeloschisis)
what is spina bifida occulta?
In spina bifida occulta, the spinal cord is properly formed, but some vertebrae, usually in the lower lumbar region do not completely form. The only sign may be a tuft of hair at the base of the lumbar vertebral column.
spina bifida cystica
- meningocele: protrusion of the spinal meninges but normal development of the spinal cord
- meningomyelocele: protrusion of the spinal cord and meninges
- myeloschisis: incomplete development of the spinal cord with the consequent joining of the neural tube to the skin and opening the neural tube to environmental elements
neural crest later becomes?
PNS, sensory and autonomic ganglia (amongst other differentiated cell types)
what are the different types of neural crest cells?
unique fate of cranial neural crest cells?
osteoblats/osteocytes, chondrocytes, odontoblasts
what are the three primary vesicles?
- secondary vesicles
what are the secondary vesicles?
- from prosencephalon: telencephalon, diencephalon
- from rhombencephalon: metencephalon, myelencephalon
what is holoprosencephaly?
- division defect; the prosencephalon divides into the diencephalon left and right hemispheres (paired telencephalon vesicles)via inward rotation, this division is induced by SHH (which is secreted initially by the notochord and later by the ventral portion of the nervous system). Failure of telencephalic division to occur results in an anomaly termed holoprosencephaly in which the fetus or infant has a single forebrain vesicle instead of right and left hemispheres.
forebrain, midbrain, and hindbrain (with their respective structures) are formed
- the bulges (vesicles) and flexures start to bend (get into proper formation)
In the 14th week, the growth of the telencephalon overshadows other parts of the nervous system, because it becomes the biggest part of the brain
when do sulcus and Gyri form?
3-7 months (prenatal)
major developmental events during the maturation period?
1) Neurogenesis: neuron generation continues THROUGHOUT life
2) Myelination: prenatally to 4 postnatal years, continues to adulthood
3) Synaptogenesis: birth to 2 years (also in late childhood), continues to adulthood
4) Dendrite growth
5) Neuronal and synaptic pruning (after 2 years of genesis)
at what age do you find the greatest number of synapses (in males and females)?
girls: 11 yrs
what is the source of cells for the maturation period?
- neuroepithelial layer
how many neurons are in the brain?
anomalies during period of cell proliferation and migration?
- lissencephaly (smooth brain, lacks fissures)
- pachygyris (thick gyro)
- microencephaly (small brain)
- heterotopia (nodules or clumps of misplaced neurons)
what are the different types of neurons?
- bipolar (found in special senses)
- pseudo unipolar (ex: sensory neurons in dorsal root ganglion)
- multipolar (most common)
Dental anesthesia relation?
Dental anesthesia actually blocks the electrical signals in the axon (the anesthesia actually utilizes sodium channel blockers)
transmission of signals b/w neurons?
Electronic signals in the axon change into chemical signals in the synaptic cleft, which then act as electronic signals on the postsynaptic cell
what are glial cells?
cells that support neurons and maintain their environment
glial cells of CNS (and functions)?
Oligodendrocytes form the myelin sheath around axons.
Astrocytes provide nutrients to neurons, maintain their extracellular environment, and provide structural support.
Microglia scavenge pathogens and dead cells.
Ependymal cells produce cerebrospinal fluid that cushions the neurons.
glial cells of PNS (and functions)?
Glial cells of the peripheral nervous system include Schwann cells, which form the myelin sheath, and satellite cells, which provide nutrients and structural support to neurons.
what are the layers of the spinal cord during development?
- neuroepithelial layer (source of cells)
- mantle layer (site of cell migration *becomes gray matter)
- marginal layer (site of myelination, *becomes white matter)
the layers of the spinal cord differentiate into _____?
- alar plate (becomes dorsal sensory horn)
- basal plate (becomes ventral motor horn)
- sulcus limitans (becomes central canal)
total number of cranial nerves?
three branches of the trigeminal nerve?
- ophthalmic branch (V1)
- maxillary branch (V2)
- mandibular branch (V3)
what is trigeminal neuralgia?
An inflammation of the trigeminal nerve, causing extreme pain and muscle spasms in the face.
Attacks of intense, electric shock-like facial pain can occur without warning or be triggered by touching specific areas of the face.
The exact cause of trigeminal neuralgia is not fully understood. A blood vessel is often found compressing the nerve.
***aka tic douloreux, facial pain
list the cranial nerves
Olfactory, optic, oculomotor, trochlear, trigeminal, abducens, facial, vestibulocochlear, glossopharyngeal, vagus, spinal accessory, hypoglossal
cranial nerves important for dentistry?
trigeminal nerve (V) and facial nerve (VII)
what is Bell's palsy?
The most common acute disease involving a single nerve and is the most common cause of acute facial nerve paralysis (>80%).
Bell's palsy is defined as a one-sided facial nerve (the cranial nerve VII) paralysis of unknown cause.
Cause an inability to control facial muscles on the affected side.
● The common presentation of this condition is a rapid onset of partial or complete paralysis that often occurs overnight.
● It is thought that an inflammatory condition leads to swelling of the facial nerve.
● Typically, the condition gets better on its own with most achieving normal or near-normal function.
● Corticosteroids have been found to improve outcomes, when used early, while anti-viral medications are of questionable benefit.
● Many show signs of improvement as early as 10 days after the onset, even without treatment.
Cognitive Load Theory (and its components)
The idea that there is a limit to working capacity.
- intrinsic CL: how difficult the matter is (manage)
extrinsic CL: external things that make learning the material harder (minimize)
- germane CL: way of streamlining the learning experience to make it easier (maximize)
components of the limbic system?
- cingulate gyrus
- parahippocampal gyrus (located in the temporal lobe)
what are the subcortical areas of the telencephalon?
- hippocampus (memory)
- amygdala (emotion)
- basal ganglia
what divides the two hemispheres of the brain?
superior longitudinal fissure
what are the lobes of the brain?
the sulcus in the neocortex?
- Lateral fissure stops midway (the straight line added is imaginary)- separates the frontal lobe from temporal. And parietal from temporal
- Parietooccipital fissure: sulcus (seen only in a sagittal view) that divides the parietal lobe from the occipital lobe
- Central sulcus: located about midway in the brain from anterior to posterior; the dividing line between the frontal and right parietal lobes
- Calcerine fissure: is a fissure that does not divide lobes. It resides only in the occipital lobe and divides it in half. Its' along this fissure that we have our visual and conscious perception
- Preoccipital notch: inferior dividing line between occipital lobe and temporal lobe. The only place that you can tell where the occipital lobe and temporal lobe end/begin. Can be seen also on the outside of the brain (the notch at the bottom that goes up a little)
what are the gyri of the neocortex
- Frontal pole: most anterior part of the brain
- Occipital pole: more posterior part of the brain
- Precentral gyrus: the gyrus anterior to the central sulcus
- Postcentral gyrus: the gyrus posterior to the central sulcus
- Supramarginal gyrus is horseshoe shaped gyrus at the tip of the lateral sulcus/fissure
- Angular gyrus is adjacent and inferior to the supramarginal gyrus
- Superior temporal gyrus: the most superior gyrus in the temporal gyrus
- Heschel's gyrus resides within the temporal lobe on the top leading edge of the lateral sulcus just inside the opercula. Runs the length of the lateral sulcus(?)
what are the types of fiber tracts of the neocortex?
Between neocortex and spinal cord or brain stem (can go either way)
Between left and right cortical areas (left and right hemispheres)
Between cortical areas on same side (within a given hemisphere)
where is the hypothalamus located?
in the inferior portion of the diencephalon
inferiorly, the hypothalamus forms the floor of the third ventricle
features of the hypothalamus and limbic system?
- optic chiasm
- maxillary bodies
- hypothalamus sulcus
- anterior pituitary
- posterior pituitary
- lamina terminalis
boundaries of the hypothalamus?