Med Neuro 1st Test

Mutations in which gene are associated with Duchenne muscular dystrophy?

Dystrophin Gene

What is hyperalgesia? What is an example?

Hyperalgesia is abnormally heightened sensitivity to pain (eg., temperature after sunburn).

What is the distinction between upper and lower motor neurons?

Upper motor neurons (UMNs) are motor neurons that originate either in the motor region of the cerebral cortex or in the brain stem and carry motor information down to the lower motor neurons

The third order neurons of the DCML system and the lateral STT are located in which thalamic nucleus? Third order neurons carrying sensation from the face are located in which adjacent nucleus?

Ventral Posterior Lateral Nucleus(VPL), the Ventral Posterior Medial Nucleus (VPM)

What are the two components that distinguish neurons from other cells in the body? What is the function of each with regard to transmitting information?

What distinguishes neurons from other cells is that they have two components that their cells do not; dendrites that receive signals from other neurons and a singular axon that transmits information to other neurons.

Before reaching the cortex axons in the DCML pathway decussate. What order are the neurons that give rise to these decussating axons? Where do they decussate?

Within the medulla oblongata, these fibres decussate (cross to the other side of the CNS). They then travel in the contralateral medial lemniscus to reach the thalamus.

Break down the meaning of "amyotrophic lateral sclerosis." What is the meaning of each word?

"A" means no. "Myo" refers to muscle, and "Trophic" means nourishment - "No muscle nourishment."

What are some strategies for managing spinal bifida with tethered cord syndrome?

-Management of shunting devices in cases of Chiari malformation and subsequent hydrocephalus -Ongoing management of bladder dysfunction if bladder control is impaired -Management of dysphagia (difficulty swallowing) and apnea (difficulty breathing) -Intervention for problems with cognitive, kidney, bowel and extremity function -Surgery to untether the spinal cord if it was undiagnosed and not treated during childhood

What are some risk factors for spina bifida?

1) folate deficiency prior to and during pregnancy—folic acid (folate, vitamin B9) deficiency causes megaloblastic anemia (very large red blood cells, insufficient in number) 2) certain anti-seizure medications—enzyme-inducing anticonvulsants, such as phenytoin, carbamazepine, primidone, and phenobarbital, are known to decrease folate levels, and valproic acid may interfere with folate metabolism 3) maternal obesity—obese women (BMI ≥ 30) had twice higher odds of having an NTD-affected pregnancy, and this risk can be mitigated with dietary folate (McMahon et al. 2013). 4) poorly controlled diabetes—diabetes is often associated with folic acid deficiency, though the nature of the associate remains unclear. 5) having previously given birth to a child with spina bifida

Al l corticospinal neurons ultimatel y synapse in the __________________ _________ _______ of the spinal cord.

All corticospinal tract neurons ultimately synapse on neurons in the ventral horn of the spinal cord.

In general, hyperreflexia and a Babinski sign are indicative of what pathological process?

A Babinski sign is indicative of an upper motor neuron lesion, as might be caused by amyotrophic lateral sclerosis (Lou Gehrig disease), brain tumor or injury, meningitis, multiple sclerosis, spinal cord injury, or stroke.

What are fasciculations?

A brief, spontaneous contraction affecting a small number of muscle fibers, often causing a flicker of movement under the skin.

What are Chiari malformations? How might tethered cord syndrome contribute?

A condition in which brain tissue extends into the spinal canal, present at birth. Most children with a myelomeningocele have a Chiari malformation, particularly in cases of tethered cord syndrome

What are dermatomes? How do they relate to radicular pain?

A dermatome is that area of skin that is innervated by a single dorsal root of the spinal cord. They have exposed nerve endings that may lead to radicular pain.

What is a nociceptor?

A nociceptor is a sensory receptor for painful stimuli. They are free "naked" nerve endings in the skin, and they are associated with pseudounipolar sensory neurons.

What is a receptive field?

A receptive field is a region of sensory space in which a stimulus will be transduced.

What is a space-occupying lesion? What is a non-space occupying lesion? What are some examples of each?

A space occupying lesions - tumors, meninges. Non-space occupying lesions - infarct, dead tissue.

What are some ways the spinal cord may be injured?

A traumatic spinal cord injury may stem from a sudden, traumatic blow to your spine that fractures, dislocates, crushes or compresses one or more of your vertebrae.

What is the difference between ascending and descending pathways in the spinal cord?

Afferent or ascending are somatosensory pathways going to the brain. Efferent or descending are motor pathways from brain to CNS.

What are the dorsal columns composed of? Which direction does information travel in the dorsal columns?

Afferent. White matter.

From which meninx do most meningiomas arise?

Arachnoid.

Where are the cell bodies for afferents from muscle spindles and Golgi tendon organs located? Where do these afferent inputs synapse on 2nd order neurons?

Between muscles and tendons

The central nervous system consists of which two major components?

Brain and spinal cord

The DCML pathway carries which sensory modalities from the periphery to the cortex?

Carries the sensory modalities of fine touch (tactile sensation), vibration and proprioception.

The nervous system can be divided into a __________________ nervous system consisting of the brain and spinal cord and a __________________ nervous system consisting of everything else.

Central nervous system, and peripheral nervous system

What is central sensitization?

Central sensitization is increased excitability of neurons in the CNS in response to stimulation, creating abnormal sensation.

What is the name of the fluid that bathes the brain?

Cerebrospinal fluid.

What are some common symptoms of cranial meningiomas?

Changes in vision, such as seeing double or blurriness. Headaches that worsen with time. Hearing loss or ringing in the ears. Memory loss. Loss of smell. Seizures. Weakness in your arms or legs. Common symptoms of cranial meningioma include headache and seizures due to intracranial pressure.

What is a commissure (or decussation)?

Commissures and decussations are areas where tracts cross from one side to the opposite side of the CNS.

Second order neurons in Clarke's nucleus carry proprioceptive information along which pathway on their way to the the cerebellum?

DORSAL SPINOCEREBELLAR TRACT (DSCT)

The middle cerebral artery (MCA) supplies what portion of the brain? What are some functions that may be affected if the MCA is occluded (blocked)?

Damage to branches of the middle cerebral artery produce characteristic cognitive, motor and sensory deficits.

Which spinal cord structures are affected by ALS? Which cortical structure(s) is affected?

Death of upper motor neurons leads to death of lower motor neurons and muscle wasting

Which motor neurons die in ALS?

Death of upper motor neurons leads to death of lower motor neurons and muscle wasting.

Distinguish between the destructive and irritative lesions in terms of their effects on the CNS.

Destructive lesion: an injury that results in damage or necrosis of tissue. Irritative lesion: sometimes termed a "stimulating lesion," this is a tissue injury that causes stimulation of the involved tissue.

What problems most characterize ALS?

Fasciculations (muscle twitches) in the arm, leg, shoulder, or tongue Muscle cramps Tight and stiff muscles (spasticity) Muscle weakness affecting an arm, a leg, neck or diaphragm. Slurred and nasal speech Difficulty chewing or swallowing.

Where does the corticomesencephalic tract originate, and where does it project to?

Fibers from area 8 (the frontal eye fields) form the corticomesencephalic tract, which innervates the nuclei of cranial nerves the control eye movement.

What are first, second, and third order neurons?

First order neuron - carries the sensory impulse from the sensory receptor to the central nervous system. Information traveling along second order neurons deccussates from one side of the CNS to the other side of the CNS. Third order neuron - carries sensory information from the thalamus to the cerebral cortex.

What are the four types of glial cells? Where are they found? What are some of their functions?

Four types of glia cells: Astrocytes - found in the brain and spinal cord, oligodendrocytes - provides myelin in the CNS and schwann cells, microglial - respond to injury or disease, epydenimal - found in the cavities of the brain.

What are some risk factors for Guillain-Barré syndrome?

GBS risk factors: being a young man, viral infections such STDs, bacterial infections, Hodgkin disease, systempic lupus erythromatosus, recent surgery.

Peripheral neuropathy often occurs in a "__________________ and __________________" distribution.

Glove and stocking distribution.

Which proprioceptive organ lies in series with muscles, and exerts a protective effect through autogenic inhibition?

Golgi Tendon Organs or GTOs

What is Gower's sign? How does it relate to proximal muscle weakness?

Gower's sign describes patients who must "walk up their own body" from all fours due to a lack of proximal muscle strength (hip and thighs).

Describe the arrangement of gray vs. white matter in the spinal cord. How does this differ from the brain?

Grey matter made up of neurons tends to occupy the center of the spinal cord and the outter regions of the cortex, White matter are the axons.

What is the difference between gray matter and white matter?

Grey matter made up of neurons tends to occupy the center of the spinal cord and the outter regions of the cortex, White matter are the axons.

Guillain-Barré syndrome is thought to be an immune-mediated disease in which the immune system attacks which other bodily system?

Guillaine-Barre syndrome (GBS) - is thought to be an immune mediated disease in which the immune system attacks gastrointestinal or respitory infaction. Comes in several variants: Acute inflammatory demyainating polyradiculeonuropathy, Miller fisher syndrome, and acute motor axonal neuropathy.

What are the bumps and grooves of the cerebral hemispheres called, and what purpose do they serve?

Gyri, sulcus, fissures. Localization.

Describe neuronal migration in the developing nervous system.

In the developing brain neurons that are destined for the cerebral cortex originate in the ventricular zone and migrate outward towards the surface of the brain.

Describe the Somatotopic organization of the ventral gray horn of the spinal cord.

In the ventral gray horn, medial motor nuclei supply axial and proximal muscle groups while lateral motor nuclei supply the more distal muscles. Notice too that flexors are mapped along a strip that is dorsal to extensors. The upper extremity is used as the example here.

What are the two paired sources of arterial blood supply to the brain?

Internal carotid arteries and vertebral arteries.

What is the difference between an ischemic and a hemorrhagic stroke?

Ischemic is a blood clot, hemorrhagic is a blood rupture

What is a Jacksonian march?

Jacksonian march: a type of seizure (named for John Hughlings Jackson) in which a seizure starts at one location in the brain, and spreads to other areas. As these seizures happen in the motor or sensory cortices, the symptoms "march" in an orderly fashion over the body.

__________________ stroke is a kind of stroke that results from occlusion of the deep penetrating arteries of the cerebral hemispheres.

Lacunar Stroke

What is a lacunar stroke? What is atherosclerosis?

Lacunar stroke is the most common kind of stroke, resulting from the occlusion of a small penetrating arteries that provide blood to the brain's deep structures. A atherosclerosis results from fatty deposits that clog arteries.

What is localization of function in the brain? What was the first clear evidence of localization of function?

Localization is the thought that certain regions of the brain have limited or a single function. First evidence of this was observed in cases of aphasia following left frontal lobe damage.

Spina bifida involves which region of the spine?

Lower spinal column

What are the 3 types of nociceptor?

Mechanical, thermal and chemical.

Recall the "bone in a bag" test. Which sensory receptors contribute to our perception of size, weight, and small physical features?

Mechanoreceptors are sensory receptors that contribute to our perception of size, weight and small physical features.

Approximately what is the peak age of incidence for meningiomas? Is there a sex predominance for incidence?

Meningiomas - peake age of incidence, 45. Non sex predominance, but females are twice as likely to be symptomatic.

Bundles of axons in the central nervous system are called by many names. What are some of these?

Pathway, funiculus, fasciculus, tract, and lemniscus

In general, what is a neural tube defect? What is the most common neural tube defect?

Neural tube defects are birth defects of the brain, spine, or spinal cord - the fetal spinal column doesn't close completely. The two most common neural tube defects is spina bifida.

The nervous system is composed of which two cell types?

Neurons and Glia

What are some components that neurons contain in common with other cells in the body?

Neurons contain all the basic components of every other cell in our bodies including a nucleus containing DNA, rough and smooth ER, ribosomes, Golgi apparatus, a cytoskeleton framework, and a membrane consisting of a lipid bolster.

What is lordosis?

Normal curvature of the spine

What is a nucleus? What is a ganglion? What is the difference between a nucleus and a ganglion?

Nuclei (CNS) are isolated aggregates of neuronal cell bodies associated with a specific function. A ganglion (PNS) is a structure containing a number of nerve cell bodies, typically linked by synapses, and often forming a swelling on a nerve fiber.

What is peripheral sensitization?

Peripheral sensitization is an increased sensitivity to an afferent nerve stimuli. This occurs after there has been an injury or cell damage to the area, and produces a flare response due to nocioceptors producing lots of neuropeptides. For example a gentle stroke to the skin which before the injury is not painful but after is interpreted as pain.

What are some symptoms of Guillain-Barré syndrome?

Prickling, pins and needles sensations in your fingers, toes, ankles or wrists. Weakness in your legs that spreads to your upper body. Unsteady walking or inability to walk or climb stairs.

The primary somatosensory cortex contains which 4 Brodmann's areas? Which somatosensory modalities does each process?

Primary Auditory Primary Visual Primary Sensory Primary Cortex

Oligodendrocytes and Schwann cells serve a similar function in different parts of the nervous system. What is this function? Where are these cells located?

Provides myelin in the CNS and schwann cells

Your friend is experiencing pain that radiates through his buttock and down the back of his left leg. Based on our readings, what is a possible cause?

Radicular pain.

Define Scoliosis and kyphosis.

Scoliosis is a curved spine. Kyphosis is excessive curvature of the spine.

Describe the differences between sensory, motor, and interneurons in terms of where their input comes from and where their output goes to.

Sensory neurons respond to a stimulus by producing a generator or receptor potential. Motor neurons sends signals from spinal cord to muscle. Interneuron is a reflexive axon that sends signal directly from sensory neuron to motor neuron.

We have talked about two proprioceptive organs. What are they named, and where are they located?

Sensory receptors located in the inner ear, muscles, tendons, and joints that use internal stimuli to detect changes in position or movement of the body or its limbs are called proprioceptors.

What is sensory transduction?

Sensory transduction is the conversion of a sensory stimulus from one form to another

Describe somatotopic mapping in the primary somatosensory cortex. How is the body mapped from head to toe? Why might this be of clinical significance?

Somatic sensations of the body are faithfully mapped onto the primary somatosensory cortex, and a similar map exists over the primary somatomotor cortex. We construct sensory and motor homunculi that represent the relative importance that the cortex assigns to various parts of the body. As pathways enter the spin they are layered, easier to see where damage to the spin was possibly made.

What is a somatotopic map? Please explain and describe where one exists in the brain.

Somatotopy is the point-for-point correspondence of an area of the body to a specific point on the central nervous system. Typically, the area of the body corresponds to a point on the primary somatosensory cortex (postcentral gyrus). Hands, feet, eyes, etc...

Increased DTRs (Deep Tendon Reflex) are indicative of what sort of lesion?

Spastic paralysis: a type of paralysis characterized by hypertonia and increased deep tendon reflex activity. Suggestive of an upper motor neuron lesion.

What are some forms of assistive devices that may be helpful in cases of spina bifida?

Spina bifida may benefit from a range of assistive devices including orthotics, crutches, walker or wheelchair.

What is spina bifida occulta? what is meningocele? What is myelomeningocele? Compare and contrast in terms of severity. What are the cauda equina?

Spina bifida occulta occurs when the vertebral arch does not form completely but other tissues develop normally. Meningocele is a form of spina bifida when the meninges protrude through a gap in the spin. Myelomeningocele is the most severe form of spina bifida, in this type the cauda equina the dura and archnoid mater of the meninges protrude through a gap in the spine. Cauda Equina "horse's tail" - the spinal nerves at the caudal end of the spinal cord.

What is the distinction between a stimulus and a sensation?

Stimulus is an OBJECTIVE, quantitative environmental interaction that is conveyed to the central nervous system. A sensation is a SUBJECTIVE, qualitative stimulus at the level of consciousness.

The ventral posterior complex of the thalamus contains __________________ order neurons that project to the __________________ somatosensory cortex and to the __________________ somatosensory cortex.

The VP complex, which contains the third order neurons of the three somatosensory pathways we have just discussed. It projects to both primary somatosensory cortex (SI) and secondary somatosensory cortex

Where are the cell bodies of first-order neurons carrying somatosensation from the face? Where do they synapse with second order neurons?

Synapse in the brainstem.

What is a syrinx? What is syringomyelia?

Syringomyelia refers to a syrinx (cyst or cavity) in the cervical spinal cord

What is a common way for syringomyelia to present?

Syringomylia may be congenital or acquired, often associated with Chiari type I malformations implicates impairments of CSF flow

What is tethered cord syndrome? How might people "grow into" it? What are some signs and symptoms?

Tethered cord syndrome is a group of disorders of the spinal cord, common consequence of spina bifida. Someone can grow into it based on the differential rate of growth between spinal column and spinal cord. Complications may include pain, bilateral weakness and numbness, bladder and/or bowel issues. Surgery may or may not be curative.

What is the Babinski sign, how is it tested, and what does it indicate?

The Babinski sign or reflex, is a response when the toes fan upwards when firmly stroking the bottom of the foot. A babinski sign is indicative of an upper motor neuron lesion and may be caused by Lou Gehrig disease, brain tumor or injury, meningitis, multiple sclerosis, spinal cord injury or stroke.

What is the Bell-Magendie Law?

The Bell-Magendie Law states that the dorsal roots of the spinal cord are sensory and the ventral roots are motor.

What are the names of the big 3 pathways? What information does each carry (specific sensory information, motor)? Where does each pathway decussate?

The Dorsal Columns Medial-Lemniscal Pathway (DCML), SENSORY - fine touch, two-point discrimination, and proprioception (position sense). The primary neuron is in the dorsal root ganglion and the central axon passes into the dorsal columns without synapsing. The Lateral Spinothalamic Trac (STT), SENSORY - affective sensation (objective stimulus such as pain, temperature). The primary neuron is in the dorsal root ganglion, the secondary neuron is in the ipsilateral dorsal horn (decussates immediatley). The second order axon crosses the cord to enter the contralateral anterlateral system. The Lateral Corticospinal Tract (LCST), MOTOR - fine movement of ipsilateral limbs. Crossed at the decussation of the pyramids, terminates on lower motor neurons of the ventral horn.

What is the "LCST?"

The Lateral Corticospinal Tract (LCST), MOTOR - fine movement of ipsilateral limbs. Crossed at the decussation of the pyramids, terminates on lower motor neurons of the ventral horn.

The autonomic nervous system can be described as having two divisions. What are they? What is the mnemonic I gave you for each? In general, what does each do?

The autonomic nervous system (one of two of the peripheral nervous system) is described as have two divisions, the sympathetic and the parasympathetic. Sympathetic is the fight for flight system (increases energy). Parasympathetic is the rest and digest system (decrease energy).

Where are the cell bodies of first order neurons carrying pain and temperature sensation from the face? Where do they synapse with second order neurons?

The cell bodies of the first order neurons carrying pain and temperature from the face are located in the trigeminal ganglion, alongside the cell bodies of neurons carrying other sensations (mechanosensation and proprioception). These synapse with second order neurons in the spinal nucleus of the trigeminal complex, then decussate and ascend in the trigeminothalamic tract before synapsing with neurons in the ventral posterior medial nucleus (VPM) of the thalamus.

Where are the cell bodies of the primary sensory neurons in the dorsal column-medial lemniscal system?

The cell bodies of the primary sensory neurons of both the anterolateral and DCML systems are located in dorsal root ganglia, DRG.

What are some examples of cutaneous mechanoreceptors? Describe some of their properties.

The cutaneous receptors are the types of sensory receptor found in the dermis or epidermis. They are a part of the somatosensory system. Cutaneous receptors include cutaneous mechanoreceptors, nociceptors (pain) and thermoreceptors (temperature).

What is a dorsal root ganglion?

The dorsal root ganglia contains the cell bodies of the sensory receptor neurons which are the first order neurons in somatosensory pathways.

Approximately 80-85% of corticospinal fibers decussate at the medullary pyramids and form the LCST. The remaining fibers descend the spinal cord in the __________________ __________________ __________________ and decussate further down, usually near the segment they supply.

The remaining fibers descend the spinal cord in the anterior corticospinal tract, and decussate further down (usually near the segment they supply).

What do the tracts of the medial group (vestibulospinal, reticulospinal, and tectospinal tracts) innervate, and what function do they serve?

The medial group includes the vestibulospinal, reticulospinal, and tectospinal tracts. These tracts innervate the trunk and lower limbs, modulating stance and gate in response to proprioceptive and vestibular input.

What are the 3 meninges? Order them from outside to inside.

The meninges are three layers of protective tissue; the dura mater, arachnoid mater, and pia mater that surround the neuraxis

Where are the cell bodies of the primary sensory neurons in the lateral spinothalamic tract? Where are the cell bodies of the second-order neurons?

The second-order neurons are located in the dorsal horn, and their axons immediately decussate via the ventral white commissure.

What is the distinction between somatic and visceral sensations?

The somatic nervous system is part of the peripheral nervous system. Major functions of the somatic nervous system (efferent) include voluntary movement of the muscles and organs and reflex movements. In the process of voluntary movement, sensory (afferent) neurons carry impulses to the brain and the spinal cord.

What is the cause of muscle atrophy in ALS?

There is an absence of myelin in the myelin stained section on the right due to death of neurons of the LCST.

What are some examples of receptors in the skin? Describe their properties, including attributes such as the optimal stimulus that is transduced by them, the size of their receptive fields, and the sensations they give rise to.

Thermo receptors, root hair plexus, pressure

Projection fibers to and from the cortex form the __________________, which continues ventrally as the __________________.

These fiberscollectively form the corona radiata, which continues ventrally as the internal capsule.

Two-point discrimination depends on the integrity of which spinal pathway? How might we test two-point discrimination using a simple paper clip?

Two point discrimination is the ability to note that two touches to the skin are really two distinct touches and not one.

What is meant by the term "myelodysplasia?" What is an "open defect?"

Typically in this type the cauda equina (horse's tail; the spinal nerves at the caudal end of the spinal cord), along with the dura and arachnoid mater of the meninges, protrude through a gap in the spine (myelodysplasia). Commonly in cases of myelomeningocele the spinal canal is open to the outside without covering by skin, muscle, or bone. We call this an open defect, and these cases must be surgically closed at birth.

How many weeks into gestation is ultrasound capable of detecting most neural tube defects?

Ultrasounds can detect about 95% of neural defects at 18-20 weeks gestation.

What is a radicle

a small rootlike part or structure, such as the beginning of a nerve. Radicular pain is associated with a nerve root and follows its dermatome.

Infarct

an area of dead tissue resulting from failure of blood supply.

Ischemia

an inadequate blood supply to an organ or part of the body.

Hemorrhage

an loss of blood from a ruptured blood vessel

The Big Three Pathways

dorsal column—medial lemniscal pathway (DCML), lateral spinothalamic tract (lateral STT; anterolateral system), lateral corticospinal tract (LCST; upcoming)

Where are the cell bodies of first order neurons in the lateral STT? Where do they synapse with second order neurons?

he first-order neurons in the pathway are located in the dorsal root ganglia at all spinal levels. Their axons ascend the tract of Lissauer, and synapse with second-order neurons.

What is "paresthesia?" What deleterious effect can high blood sugar over a prolonged period have on nerves? What symptoms might develop?

paresthesia (tingling) or numbness on the contralateral side of the body, Irritative lesions may produce sensory focal seizures, and often affects the adjacent motor cortex.