Neuro Flashcards
Neuron staining
Nissl stain - stains RER
Doesn’t stain axons, there isn’t any RER there!
Axonal injury
Wallerian degeneration - distal degen, retraction proximally
If PNS, potential regeneration
Astrocytes
give functions, stain, derivation
Physical support, repair, K+ metabolism
necessary for blood-brain barrier
- holds glycogen fuel reserve
- marker GFAP
- reactive gliosis
- derived from neuroectoderm!
Microglia
scavenger cells of CNS
- mesodermal mononuclear origin
- HIV: fuse to form multinucleated giant cells
- not stained by Nissl
Schwann cell
1: 1 ratio with PNS cells
- promote axonal regeneration
- neural crest!
destroyed in Guillain-Barre syndrome
- acoustic neuroma
Oligodendrocytes
1: many ratio with CNS cells
- injured in MS, PML
- neuroectoderm
- fried egg appearance
Peripheral nerve structure
Endoneurium
Perineurium
Epineurium
Endoneurium: single nerve fibers (site of inflamm infiltration in G-B)
Perineurium: surrounds fascicle of nerve fibers, rejoined in microsurgery in limb attachment
Epineurium: dense connective tissue, contains fibers and blood vessels
Blood brain barrier (3 things)
Tight junctions (endothelial cells)
Basement membrane
Astrocyte foot processes
- glucose/AAs cross slowly
- non-polar/lipid-soluble cross rapidly
- no BBB: area postrema, neurohypophysis
Hypothalamus (regulates TAN HATS, give hormones and site of synthesis)
Thirst, Adenohypophysis, Neurohypophysis, Hunger, Autonomic regulation, Temp regulation, Sexual urges
Supra optic nucleus: ADH
Paraventricular: oxytocin
Inputs: area postrema, OVLT = osmolarity sensor
Nuclei of hypothalamus Lateral Ventromedial Ant. hypot Post. hypot Suprachiasmatic
Lateral: hunger Ventromedial: satiety Ant. hypot.: cooling/parasympathetic Post. hypot: heating, sympathetic Suprachiasmatic: ciracidan rhythms (sleep = charismatic)
Sleep physiology
Light –> suprachiasmatic nucleus –> NE –> pineal gland –> melatonin
Thalamus nuclei VPL VPM LGN MGN VL
- relay for all sensory information except olfaction
VPL: STT/DCML tracts (everything but face!)
VPM: trigeminal/gustatory (face sensation, taste)
LGN: vision (L for light!)
MGN: hearing
VL: basal ganglia, cerebellum
Limbic system functions (5 F’s)
feeding fleeing fighting feeling sex
Cerebellum inputs, outputs, lesions
Input:
- middle cerebellar peduncle = contralateral cortex
- inferior cerebellar peduncle = ipsilateral proprioceptive
Output:
- superior cerebellar peduncle = contralateral cortex to modulate movement
Lesions: lateral will fall to affected side, medial will be truncal ataxia
Basal ganglia anatomy
Describe direct and indirect pathways
Striatum = putamen (motor input) + caudate (cognitive input)
Motor functions all start in the frontal cortex
Direct pathway = D1R leads to increased GABA from striatum to inhibit GPi inhibitory neurons, leading to increased thalamus activity and increased movement
Indirect pathway = D2R leads to inhibition of GPe, releasing their inhibition of subthalamic nucleus, allowing for activation of GPi and inhibition of thalamus
Parkinsons
decreased DA secretion, leads to overall less movement and also less inhibition of movements at rest
-alpha synuclein form Lewy bodies (eosinophilic, intracellular inclusions)
TRAPS: tremor, rigidity, akinesia, postural instability, shuffling gait
Huntinton
CAG repeats
Caudate loses Ach and GABA
Aphasia Broca Wernicke Conduction Global motor Global sensory
Broca - nonfluent, impaired repetition (inferior frontal gyrus)
Wernicke - fluent, impaired comp/rep (superior temporal gyrus)
Conduction - fluent, poor rep (arcuate fasciculus)
Global motor - nonfluent, intact otherwise
Global sensory - poor comp, intact everything
Amygdala lesions
Hyperphagia, hypersexuality, hyperorality (HSV-1 = infectious cause)
Parietal-temporal lesions
Contralateral hemispatial neglect
Midbrain
Reticular-activating system lesions
Decreased arousal, wakefulness
Mamillary bodies lesions
W-K syndrome, confabulation!
Subthalamic nucleus lesions
Contralateral hemiballismus
Hippocampus lesions
anterograde amnesia
Frontal eye fields lesions
Conjugate toward the side of the lesion
Cerebral perfusion
Driven by pCO2 (central medullary chemoreceptors)
CPP = MAP - ICP
Medial medullary syndrome
Paramedian ASA branches infarct
Leads to hemiparesis, decreased proprioception, hypoglossal dysfunction (tongue motor symptoms)
Lateral medullary syndrome
PICA or verterbral artery
CN V, VII, VIII, IX, X, XII all affected
vomiting, vertigo, nystagmus, HOARSENESS, DYSPHAGIA
Lateral pontine syndrome
AICA
Paralysis of face, decreased lacrimation/salivation
Epidural hematoma
Middle meningeal, lucid interval, III palsy,
transtentorial herniation
Subdural hematoma
bridging veins, slow evolving
Subarachnoid hemorrhage
Saccular aneurysm rupture (Ehlers-Danlos, ADPKD)
Xanthochromic LP
Intraparenchymal hemorrhage
Systemic hypertension, amyloid angiopathy
Most often in the basal ganglia or internal capsule
Ischemia histology progression
12-48 hrs: red neurons 24-72 hrs: necrosis, neuts 3-5 days: macrophage/microglia infiltration 1-2 weeks: reactive gliosis >2 weeks: scar
Pseudotumor cerebri dx, findings, risk factors
increased ICP w/o evidence of cause
Diplopia (VI palsy), papilledema
Risk factors: Vitamin A excess, danazol (endometriosis drug)
Tx: weight loss, acetazolomide, topiramate, shunt
Polio/SMA effect on spinal cord
LMN damage, destruction of anterior horn
ALS effect on spinal cord
Super oxide dismutase, UMN and LMN lesions
B12 deficiency effect on spinal cord
demyelination of dorsal columns, lateral corticospinal tracts
Polio
LMN death in anterior horn
Virus recovered from stool/throat
Friedrich ataxia
GAA on ch. 9 (frataxin)
- staggering gait, falling, hypertrophic cardiomyopathy
Reflexes
Biceps: C5 Triceps: C7 Cremaster: L1 Patella: L4 Achilles: S1 Anal: S3
Superior colliculi
Conjugate vertical gaze cetner
Parinaud syndrome = lesion, paralysis of conjugate gaze
Middle cranial fossa pathways
Optic canal: CN 2 Superior orbital fissure: CN 3, 4, 5-1, 6 Foramen rotundum: V2 (maxillary) Foramen ovale: V3 (mandibular) Foramen spinosum: middle meningeal
Posterior cranial fossa pathways
Internal auditory meatus: CN 7, 8
Jugular foramen: Cn 9, 10, 11, jugular vein
Hypoglossal: 12
Foramen magnum: 11 (spinal levels only)
Vagal nuclei
Nucleus solitarius - visceral sensory info
Nucleus ambiguus - motor innervation of pharynx/larynx/upper esophagus
Dorsal motor nucleus - parasympathetics to heart/lungs/upper GI
Cavernous sinus
either side of the pituitary, collect blood from the eyes to the internal jugular
- CN 3, 4, 5-1, 6 and sympathetic fibers
- also, internal carotid
- syndrome: ophthamloplegia, decreased corneal sensation, Horner syndrome, CN 6 most susceptible
Inner ear
low freq = apex near helicotrema (wide, flexible)
high freq = base of cochlea (thin, rigid)
Stapes hits the oval window to stimulate inner ear
Muscles of mastication
closes: masseter, temporalis, medial pterygoid
opens: lateral pterygoid
V3 nerve
