Development of the Nervous system

endoderm
mesoderm
ectoderm
    formation and growth of the neural tube
        neural plate
        neural folds and groove
        neural tube
        anterior and posterior neuropores
        alar and basal plates of the tube
        cell division, migration, and differentiation
        3 brain vesicles--> 5 brain vesicles
        midbrain, pontine and cervical flexures
        neural crests and what they turn into
neural tube defects (see study guide)
        anencephaly
        spina bifida ( 3 types: occulta, with meningocoele, with myelomeningocoele)
            alpha-fetoprotein
            sonogram
            change in length of spinal cord vs spinal column during development
            Arnold-Chiari malformation --> hydrocephalus in addition to spina bifida
cerebral palsy ( what is it, what causes it, what impairments are seen, types (spastic, ataxic, athetoid) (see study guide)
problems with cell proliferation and/or migration
    lissencephaly, microcephaly
    autism 
    fetal alcohol syndrome
continued development of nervous system after birth

Spinal Cord

vertebrae and meninges covering the cord
    vertebral canal containing cord
    intervertebral foramina allowing nerves to exit
31 spinal segments, each with a pair of spinal nerves
    dorsal and ventral roots
    dorsal root ganglia
gray matter vs white matter of the cord
    dorsal, ventral and lateral horns
    columns of white matter containing the long tracts of the spinal cord
    central canal
    DM sulcus and VM fissure almost dividing cord in half
    conus medullaris
    cauda equina
    filum terminale
    lumbar puncture (spinal tap) or drug injections around spinal cord
basic functions of all segments (sensory, motor, autonomic)
ascending spinal tracts
    3 neuron sequence from periphery to cortex
        primary afferent neurons
        second-order neurons
            decussation
        third-order neurons
dorsal column pathway or tract (discriminative (fine) touch, proprioception)
        dorsal column (fasciculus cuneatus and fasciculus gracilis)
        nuclei cuneatus and gracilis in medulla
        sensory decussation
        VP thalamus
        somatosensory cortex of parietal lobe
pathological changes in dorsal column pathway
        degeneration of dorsal column neurons, e.g. in some cases of MS, leading to loss of dorsal column sensations
            astereognosis
        tabes dorsalis and other conditions that can damage the dorsal columns (MS, peripheral neuropathy, B12 deficiency)
        sensory ataxia, Romberg's sign
route taken by the ascending spinothalamic pathways or tracts (pain, temperature, and gross touch)
        release of bradykinin, prostaglandins, histamine when tissue is injured
        release of neurotransmitter "substance P" by first neuron in pathway
        substantia gelatinosa
        second neuron crosses in spinal cord
        lateral white matter of cord
        VP thalamus
        somatosensory cortex of parietal lobe
"gate control" for pain in substantia gelatinosa portion of dorsal horns and what "closes the gate"
descending pain suppression pathway from midbrain periaqueductal gray
mislocalizing the source of ANS pains ("referred pain")
  disorders related to spinothalamic pathway (see study guide)
    herpes zoster (shingles)
    syringomyelia
 
descending pathways or tracts of the spinal cord

lower (alpha) motor neurons - "final common path"
    what are they
    motor units (motor neuron and its extrafusal muscle fibers)
    what are the symptoms seen if LMNs are damaged
        loss of voluntary and reflexive movements of the involved muscle fibers
        flaccid paralysis
       denervation atrophy of the involved muscle fibers
            fasciculations following denervation
    example of a disorder affecting LMNs
        poliomyelitis

upper motor neurons
    what are they
    what are the symptoms if  UMNs are damaged
    example of disorder affecting UMN

corticospinal tract or pathway (functions and path it takes through brain and cord) (aka pyramidal tract)
    cortex
    internal capsule
    pyramids of medulla
    crosses at medulla-cord junction "decussation of the pyramids"
    lateral corticospinal tract in lateral white matter of cord
symptoms of corticospinal damage (what would you be unable to do, what aspects of your behavior would change)

extrapyramidal pathways
    rubrospinal - to flexors
    vestibulospinal - to extensors
    reticulospinal - modulate reflexes and muscle tone
    tectospinal - reflexive movements to visual stimuli
other parts of motor system influencing these descending pathways : basal ganglia and cerebellum
abnormal postures after UMN injury (decorticate and decerebrate)

spinal reflexes
    monosynaptic stretch reflex - neurons involved?
        stretch (muscle spindle) receptors containing intrafusal muscle fibers
        knee jerk (a "deep tendon" reflex)
        functions of the stretch reflex
    flexor or withdrawal reflex of hand
    withdrawal reflex and crossed extensor reflex of leg
    UMN modulation of spinal reflexes - can increase or decrease how easily stretch reflex is triggered

changes in spinal reflexes after UMN damage
    positive Babinski reflex
    hyperactive stretch reflex
    clonus
spastic paralysis

gamma motor neurons (what they are, what they synapse on)
    gamma motor neuron modulation of stretch reflex
    UMN influence on gamma motorneurons
    How this relates to the symptoms of UMN damage

disorder affecting both LMNs and UMNs:
    amyotrophic lateral sclerosis (see study guide)

anatomy of spinal cord cross sections - how the changes in amount of white matter and gray matter relate to the paths we've discussed