Anatomy/Neuropathology Flashcards
What is the path of the direct light reflex?
retinal ganglion cells → optic nerve → optic tract → brachium of superior colliculus → pretectal area → posterior commissure → both oculomotor nuclei → Edinger–Westphal subnucleus → ciliary ganglion → pupillary sphincter muscle
What is the function of RiMLF? Location? input and output?
located above the oculomotor nucleus in the MLF at the junction of the midbrain/diencephalon. It is the main center for vertical eye movements (especially downward). It reacts to vestibular and visual stimulation:
Input: superior vestibular nucleus and PPRF.
Output: mainly to the oculomotor complex (inferior rectus portion).
What are the functions of the periaqueductal gray?
Central analgesia, vocalization, control of reproductive behavior, aggressive behavior, and upward gaze
Location, input, and output of the interpeduncular nucleus:
Located just dorsal to the interpeduncular fossa.
Input: habenular nucleus via fasciculus retroflexus.
Output: diffuse cholinergic fibers to various parts of the CNS.
What is the organization of the crus cerebri?
Crus cerebri:
Corticospinal and corticobulbar tracts: middle two-thirds of the crus cerebri (lower extremities located laterally).
Corticopontine tracts: extreme medial and lateral ends of crus cerebri (frontopontine medially and parieto-temporo-occipitopontine located laterally).
what are the outputs of the pontine reticular formation?
Pontine reticular formation:
Sends crossed reticulospinal fibers (muscle tone) → spinal cord LMN.
Fibers to central tegmental tract (wakefulness) → thalamic intralaminar nuclei (for arousal).
Function of the locus ceruleus and location:
Locus ceruleus:
Pigmented (melanin).
Neurotransmitter: NE (primarily excitatory but some receptors inhibitory) with wide projections.
Function: controls cortical activation and paradoxical (rapid eye movement) sleep.
located in the pons
What is secreted by the Raphe nucleus and its location? inhibitory or excitatory? effect?
Raphe nucleus in the lower pons/medulla—inhibits via 5-HT; mostly influences the thalamus (for sleep and restful functions), but also the cortex (for sleep) and spinal cord (to decrease pain).
What are the projections of the substantia nigra and their effects?
projects inhibitory fibers that release DA to the caudate and putamen. However, note that DA is excitatory in the hypothalamus and limbic system
What is secreted by Gigantocellular layer of the reticular activating system and what are the projections? Where is it located?
in the pons/midbrain—stimulates via ACh; neurons relay one branch to the cortex and one branch to the reticulospinal tract.
What are the skin receptors (6), their location, sensation, receptive field, and type of fiber used?
What is ferrugination?
occurs when dead neurons become encrusted with Fe2+ and Ca2+ salts
What is central chromatolysis? What are the cellular changes? Syndromes when this phenomenom is seen?
occurs after an injury to an axon near the cell body. The Nissl substance disappears, the nucleus becomes eccentric, and the cell body enlarges. It is seen in the anterior horn cells with anterior nerve root compression and Guillain–Barré syndrome. The cells may progress to death or recover.
What are the three most common bugs that cause meningitis? What is the common age groups and respective treatment?
three most common causes of meningitis (i.e., H. influenzae, S. pneumoniae, and Neisseria meningitidis) all normally colonize the nasopharynx
neonate: GBS, e. coli, and listeria
4-12 weeks: s. pneumo
3mo to 3y: h. flu. tx- cephalosporins. in children adding steroids decreases risk of deafness
children to young adults: n. meningitides. tx- penicillin or chloramphenicol
elderly: s. pneumo. Risk is increased with trauma (it is the normal flora of the mastoid, ear, sinus, and nose), infection, and sickle cell disease. tx- penicillin
What is the organism that causes whipple disease? clinical symptoms, histology and treatment?
Whipple disease: It is a chronic multisystem disease caused by Tropheryma whippelii. It is characterized by weight loss, abdominal pain, diarrhea, lymphadenopathy, arthralgia, and Alzheimer’s disease-like neurologic symptoms (10%). Pathologic examination demonstrates foamy macrophages with PAS-positive granules. These are degenerating bacilli. Treatment is with tetracycline.
Sarcoid causes non caseating granulomas in what CNS location? What enzyme is elevated in blood? treatment?
hypothalamus
ACE
steroids
What is Meningovascular syphilis (lues), when does it occur, CNS manifestations?
occurs after 7 years and is characterized by subacute or chronic meningitis with perivascular lymphocytes, Heubner arteritis with intimal proliferation and vessel obliteration, and multiple ischemic strokes in the basal ganglia and MCA territory
deletions in chromosome 9p in tumors means a loss of?
cdkn2a/p16/ARF
What is the most frequent bug found in brain abscesses?
microaerophillic and anaerobic streptococcus
What are the clinical signs of arsenic poisoning? treatment?
mees transverse white lines on fingernails, malaise, hyperpigmentation on the palms and soles
BAL
What are the clinical signs of lead poisoning? treatment?
children: encephalopathy
adults: anemia and demyelinating polyneuropathy. urine excretion of coproporphyrin
BAL, penicillamine, EDTA
What are the clinical signs of mercury poisoning? treatment?
mad hatter, cerebellar signs, renal tubular necrosis
penicillamine is the treatment. Do not use BAL as it increased brain levels
Where are neurofibrillary tangles and plaques found? stain? composition?
both intracytoplasmic
both use silver stain
plaques compsed of beta/A4 protein
tangles are immunoreactive to tau protein
Herpes infection of the geniculate ganglion (Ramsay Hunt syndrome) symptoms:
This may cause dysfunction of CN VII with altered sensation of taste, facial weakness, and vesicular eruptions on the pinna and in the external auditory canal.
PML appearance in the brain on imaging and histology?
bilateral, asymmetric, subcortical, spares the cortex, and usually starts in the posterior centrum semiovale. There is minimal cellular infiltration, central destruction of oligodendrocytes, demyelination, and peripheral swollen irregular oligodendrocytes with ground-glass nuclei and intranuclear inclusions of “stick-and-ball” viral particles. CSF is normal
prions cause CJD and manifest as:
myoclonus, pyramidal, and extrapyramidal degeneration, dementia, ataxia, and visual deterioration
What are the symptoms of prion caused Gerstmann–Sträussler syndrome and inheritance?
ataxia, dysarthria, hyporeflexia, and cognitive decline, without myoclonus. Transmission is both autosomal dominant and sporadic, and Kuru plaques are seen in the cerebellum
What are the symptoms of prion induced Fatal familial insomnia and the pathology?
Fatal familial insomnia: Symptoms are sleep disturbance, agitation, mild cognitive changes, and dysautonomia; characterized by thalamic atrophy.
Rasmussen chronic encephalitis may be caused by:
CMV infection or antibodies to glutamate receptors
Pseudolaminar cortical necrosis: cause, affected cortical layers?
It is caused by generalized hypoxia, not focal. The middle cortical layers are affected (layers 3, 5, and 6), and there is frequent gyriform hemorrhage.
Causes, symptoms, and affected nuclei of the stroke syndrome Millard–Gubler syndrome:
From a lesion in the pons. Findings are facial and abducens palsies with contralateral hemiplegia. It is caused by ischemia or tumor and involves CNs VI, VII, and the corticospinal tract.
Causes, symptoms, and affected nuclei of the stroke syndrome Benedikt’s syndrome:
From a lesion in the tegmentum of the midbrain caused by ischemia, hemorrhage, TB, or tumor. Findings are oculomotor palsy with contralateral hemiplegia and cerebellar ataxia and tremor. It involves CN III, the red nucleus, corticospinal tract, and brachium conjunctivum.
Causes, symptoms, and affected nuclei of the stroke syndrome Weber’s syndrome:
From a lesion in the midbrain caused by vascular occlusion, tumor, or aneurysm. Findings are oculomotor palsy with crossed hemiplegia. It involves CN III and the corticospinal tract.
What does Ciliary muscle contraction cause? innervation? effect on eyes refractive power?
—causes the eyeball to become narrower and thus decreases tension on the lens, allowing it to become more spherical. When the ciliary muscle relaxes, the lens is pulled flat. The ciliary muscle is innervated by parasympathetic nerves and serves to increase the eye’s refractive power for accommodation to focus on closer objects.
What is the neurotransmitter to the rods and cones? neurotransmitter for amacrine cells? inhibitory or excitatory?
The neurotransmitter of rods and cones is glutamate. Amacrine cells have at least eight types of neurotransmitters; all of them are inhibitory.
Parasympathetic innervation of the eye:
Edinger–Westphal nucleus, transmitting via the third nerve → ciliary ganglion behind the eye → short ciliary nerves → ciliary muscle (for accommodation) and iris sphincter (for miosis)
Sympathetic innervations of the eye:
T1 level → sympathetic chain → superior cervical ganglion, up along the carotid artery to the small vessels, and then as the long and short ciliary nerves to the eye’s radial iris fibers (for mydriasis), to Müller’s muscle of the eyelid and weakly to the ciliary muscle
“What allows for the voluntary retention of urine once a full bladder has induced an increase in bladder parasympathetic tone?
Activation of S2–S4 a-motor neurons causing contraction of the external urethral sphincter striated muscle fibers
“This toxin inhibits RNA translation”
Diphtheria toxin
“What substance releases factor VIII from von Willebrand factor?”
Thrombin
The utricle will respond to stopping at a stop sign or jumping rope?
Stop sign.
Both the utricle and saccule respond to changes in linear acceleration with the utricle being oriented horizontally and the saccule vertically. Deceleration in a motor vehicle traveling straight or a head tilt downward each causes anterior displacement of the otoliths in the macula of the utricle and excites hair cells that respond to movement in that direction. In contrast, the act of jump roping mainly would be sensed by action in the saccule. (A, D) Both of these activities cause a shift of endolymph in the semicircular canals that is detected in the ampulla of each canal. The “ampullae respond to angular acceleration. (B, E) The vestibular system only responds to changes in acceleration and will adapt with no or constant motion in the same direction.
A patient with pituitary adenoma presents with arrythmias and airway obstruction. What is the hormone?
“Excess growth hormone in adults results in arthropathy, paresthesias, polyneuropathy, cardiomyopathy, arrhythmias, upper airway obstruction due to palatal/pharyngeal tissue overgrowth, increased risk for malignancies and colon polyps, and diabetes.
What are the major proinflammatory cytokines? Anti inflammatory?
“major proinflammatory cytokines are the interleukins (IL) IL-1, IL-6, IL-8, TNF-α (tumor necrosis factor-alpha), and IFN-γ (interferongamma). These produce fever, tissue destruction, and inflammation. The major anti-inflammatory cytokines include IL-4, IL-6, IL-10, IL-11, and IL-13. Of note, IL-6 can be anti- or proinflammatory depending on how it is used in a signaling cascade
“What is a miniature end-plate potential?”
“Response of the postsynaptic terminal caused by the release of a single vesicle into the synaptic cleft
Pathology shows blood-filled cavernous spaces separated by fibrous septa surrounded by fibroblasts, histiocytes, and multi-nucleated giant cells, but not endothelium. Which of the following is the most likely diagnosis?
imaging shows an aneurysmal bone cyst. On imaging these are sharply defined, expansile osteolytic lesions, with thin sclerotic margins. The occurrence of a concomitant fibrous dysplasia and aneurysmal bone cysts in calvarium is exceedingly rare, but there is a report that a secondary form of aneurysmal bone cysts may arise from a disruption in the osseous circulation caused by a primary lesion
