Neuro Flashcards
Arnold-Chiari Type I
Adults: low-lying cerebellar tonsils below formen magnum–> vertebral canal
- Symptoms: headaches, cerebellar symptoms (ataxia), syringomyelia
Arnold-Chiari Type II
Babies: Cerebellar tonsil and vermian heniation through foramen magnum
- Aqueductal stenosis and hydrocephalus
- Thoraco-lumbar myelomeningocele
- paralysis below defect
Symptoms: difficulty swallowing, dysphonia, stridor, apnea
Dandy-Walker syndrome
Agenesis of cerebellar vermis with cystic enlargement of 4th ventricle (fills posterior fossa)
- hydrocephalus
- Spina bifida
Symptoms: postural instability, gait problems
Meissner’s corpuscles
Large, myelinated fibers (adapt quickly)
Seen in glabrous (hairless) skin
Dynamic, fine/light touch; position sense
Pacinian corpuscles
Large, myelinated A-beta fibers
- Deep skin layers, ligaments, joints
Rapid vibration, pressure sense
Merkel’s discs
Large, myelinated fibers; adapt slowly
- Hair follicles
Pressure, deep static touch (shapes, edges), position sense
Endoneurium
Invests single nerve fibers
- Guillain-Barre= inflammation of endoneurium
Perineurium
Surrounds fasicle of nerve fibers
- Permeability layer
- Rejoined in microsurgery for limb reattachment
Epineurium
Surrounds entire nerve (dense connective tissue)
Golgi Tendon Organ
Sensory receptor at muscle-tendon junction
- in SERIES with extrafusal muscle fibers
- Ib innervation–> inhibitory
GTO activated with excess contraction—> relaxation
Intrafusal muscle spindles
Ia and II innervation
- Sensitive to stretch (stops excess stretch force)
Locus Ceruleus
Site of NE formation
- SAM required to transform NE to epi
NE= tyrosine derived (like DA, epi)
Dopamine
Tyrosine-derived neurotransmitters
- Found in Ventral tegmentum, SNc (substantia nigra pars compacta)
5-HT (serotonin)
Tryptophan–> BH4 (pyridoxine= B6)–> 5-hydroxytryptamine–> serotonin
- found in Raphe nucleus (pons)
Basal nucleus of Meynert
ACh synthesis
- Decreased in Alzheimer’s, Huntington’s
- Increased in REM sleep
Metencephalon
Pons and cerebellum
+ Upper part of 4th ventricle
Part of Hindbrain (Rhombencephalon)
Myelencephalon
Medulla
+ Lower part of 4th ventricle
Part of Hindbrain (Rhombencephalon)
Diencephalon
Thalamus + Third ventricle
Mesencephalon
Midbrain + aqueduct
Nucleus accumbens
Site of GABA synthesis
- Glutamate converted to GABA by glutamate decarboxylase
*Decreased synthesis in anxiety, Huntington’s
GABA receptor types:
- GABA(A)= Cl- influx in brain (ion channel)
- GABA(B)= K+ efflux, decreased Ca+2 influx inhibit adenylyl cyclase (G-protein)
- GABA(C)= Cl- influx in retina
*Decreased GABA(A) in long term EtOH/benzo use–> withdrawal seizures
Cross BBB
Glucose and AA by carrier-mediated transport (slow)
Non-polar/lipid-soluble cross rapidly
Specialized areas with fenetrated capillaries:
- Area postrema (vomiting post-chemo)
- OVLT (osmotic sensing
- Neurosecretory products (neurohypophysis–> ADH)
- Hypothalamic inputs/outputs
Hypothalamus areas
Lateral: regulates hunger
- Inhibited by leptin
- Destruction–> anorexia
Ventromedial: regulates satiety
- Stimulated by leptin
- Destruction (craniopharyngioma)–> hyerphagia
Anterior: cooling, parasympathetic
Posterior: Heating, sympathetic
Suprachiasmatic nucleus: circadian rhythm
**Posterior pituitary (neurohypophysis) recieves axonal projections from supraoptic nuclei (ADH) and paraventricular nuclei (oxytocin)
- Anterior pituitary (adenohypophysis) recieves stimulation from hypothalamus:
- DA–> inhibits Prolactin
- GHRH–> GH release
- LHRH–> LH release, FSH release
- CRH—> ACTH release
- TRH–> TSH release
Thalamus
VPL: Pain, temp, pressure, touch, vibration, proprioception
VPM: Face sensation and taste (Makeup on the face)
LGN: Vision
MGN: Hearing
VL: motor
Thalamus strok= post-stroke pain (burning/stabbing sensation)
Cerebellar peduncles
Input= climbing, mossy fibers
- Inferior: ipsilateral proprioceptive info
- Middle: Contralateral cortex
Output= Purkinje fibers
- Superior: Deep nuclei to contralateral cortex
- Deep nuclei (lat–> med): Dentate, Emboliform, Globose, Fastigial (Don’t Eat Greasy Foods)