Comprehensive Board Review Flashcards
What are Virchow-Robin spaces?
Perivascular potential space, between blood vessels and the surrounding sheath of leptomeninges entering the nervous tissue (brain and spinal cord).
What ion(s) are increased in CSF compared to plasma?
Chloride.
What ion(s) are decreased in CSF compared to plasma?
Potassium, calcium, uric acid and glucose.
Describe Froin’s syndrome.
CSF xanthochromia and clotting (due to the presence of fibrinogen) occur when CSF is loculated, usually in the lumbar thecal sac.
CSF protein is increased (up to 1000mg/L).
Sites of CSF production?
70% choroid plexus, 18% ultrafiltrate, 12% metabolic H20 production.
What nuclei controls CSF production?
Raphe nuclei send axons (serotonin) to the periependymal vessels.
Rate of CSF production.?
0.3-0.37mL/min or 20mL/hr.
The BBB is formed by what?
Capillary endothelial tight junctions (mainly).
Pinocytic activity in endothelial cells.
Astrocytic foot processes.
What are the circumventricular organs?
- Organum vasculosum (lamina terminalis).
- Neurohypophysis.
- Median eminence of the hypothalamus.
- Subfornical organ.
- Subcommissural organ.
- Pineal gland.
- Area postrema.
Functions of the organum vasculosum (lamina terminalis).
- Outlet for hypothalamic peptides.
2. Detect peptides, amino acids, and proteins in the blood.
Functions of the neurohypophysis.
Outlet for hypothalamic hormones (oxytocin and vasopressin).
Functions of the median eminence of the hypothalamus.
Release hypothalamic-releasing factors.
Functions of the subfornical organ.
- May be involved in body fluid regulation.
- Located between the foramina of Monro.
- Connected to the choroid plexus.
Functions of the subcommissural organ.
- Function unknown.
- Located under the posterior commissure.
- The only circumventricular organ with an intact BBB.
Functions of the pineal gland.
- Melatonin production.
2. Role in circadian rhythm.
Functions of the area postrema.
- A chemoreceptor that induces emesis when stimulated by digitalis or apomorphine.
- Located on the floor of the 4th ventricle.
- The only paired circumventricular organ.
CBF in normal brain tissue.
50 mL/100g brain tissue per minute.
CBF in the ischemic penumbra (reversible).
8-23mL/100g brain tissue per minute.
CBF in irreversible neuronal death.
<8mL/100g brain tissue per minute.
What percentage of the population has a hypoplastic vertebral artery?
40%.
Intraosseus branches off the C3 segment of the ICA.
- Caroticotympanic artery.
- Vidian artery.
- Periosteal arterial branches.
Describe a persistent stapedial artery.
Embryonic stapedial artery that fails to involute (primitive hyoid branch of the ICA).
Courses from the vertical segment, exits through a bony canal on the cochlear promontory and traverses the footplate of stapes to terminate as the middle meningeal artery.
If present, the foramen spinosum is either small or absent with enlarged geniculate fossa (Y-shaped).
Describe a persistent otic artery.
Primitive otic artery that fails to involute.
Embryonic carotid-basilar anastomoses.
Connects petrous ICA to embryonic dorsal longitudinal neural arteries.
Branches of the intracavernous (C4) ICA.
- Meningohypophyseal trunk (posterior trunk).
- Inferolateral trunk (artery of the inferior cavernous sinus).
- Medial trunk (McConnell’s capsular arteries).
Branches off the meningohypophyseal trunk.
- Tentorial artery (of Bernasconi and Cassinari) - supplies tentorium.
- Inferior hypophyseal artery - supplies neurohypophysis.
- Dorsal meningeal artery (clival branch) - supples CN VI and part of the clivus.
Describe a persistent trigeminal artery.
Most common primitive internal carotid artery-basilar anastomosis.
Associated with higher incidence of vascular abnormalities (25%), aneurysms are most common.
Branches of the intracaverous ICA.
- Ophthalmic.
- Superior hypophyseal.
- PCOM.
- Anterior choroidal.
- Branches to the hypothalamus, optic nerve and chiasm.
Vascular territories of the superior hypophyseal arteries?
They course beneath the optic nerve to supply the pituitary (anterior lobe, pituitary stalk), tuber cinerum, and optic nerve and chiasm (inferior surface).
These arteries anastomose with the arteries of the contralateral as well as the inferior hypophyseal arteries to form the hypophyseal portal system.
What is a fetal PCA?
When PCOM diameter is the same as PCA.
Failed regression of fetal PCA leads to dominant blood supply of occipital lobes from the ICA rather than from the vertebrobasilar system.
Origin of the anterior choroidal artery.
Posteromedial surface of the ICA, 2-4 mm distal to the PCOMs origin.
What are the two segments of the anterior choroidal artery?
- Cisternal segment - courses posteromedially within the suprasellar cistern beneath the optic tract, then turns posteromedially around the uncus.
- Intraventricular segment - continues from the cisternal segment. Prior to reaching the lateral geniculate body, it turns posterolaterally through the crural and ambient cisterns to enter the choroidal fissure (plexal point) of the temporal horn.
What are the branches of the ACA?
A1 - horizontal/precommunicating segment.
A2 - vertical/postcommunicating segment.
A3 - distal ACA and cortical branches.
Branches off the A1 segment?
1-12 perforating arteries called the medial lenticulostriate arteries (medial proximal striate arteries).
Course through the anterior perforated substance to supply the optic nerve (superior surface), optic chiasm, anterior hypothalamus, septum pellucidum, anterior commissure, and pillars of the fornix and anteroinferior striatum.
Location of the anterior communicating artery?
Located in hte cistern of the lamina terminalis.
Two or more perforators arise from the Acomm and supply the infundibulum and optic chiasm.
Branches off the A2 segment.
- Recurrent artery of Heubner - arises just proximal (or more commonly just distal) to the ACOM and courses back towards A1.
- Orbitofrontal artery.
- Frontopolar artery.
- Anterior internal frontal artery.
Vascular territory of the recurrent artery of Heubner?
Head of the caudate, anterior limb of the IC, anterior putamen and globus pallidus, septal nuclei, and inferior frontal lobe.
What are the branches off the A3 segment?
- Callasomarginal.
- Pericallosal.
- Middle internal frontal artery.
- Posterior internal frontal artery.
- Paracentral artery.
- Superior parietal artery.
- Inferior parietal artery.
What are the segments of the MCA?
M1 (horizontal segment).
M2 (insular segment).
M3 (opercular segment).
M4 (cortical segment).
What are the branches off the M1 segment?
- Uncal artery.
- Temporopolar artery.
- Anterior temporal artery.
- Lateral lenticulostriate arteries.
What are the branches off the superior trunk of the M2 segment?
- Orbitofrontal branch.
- Prefrontal branch.
- Precentral branch.
- Central branch.
- Anterior parietal branch.
What are the branches off the inferior trunk of the M2 segment?
- Posterior parietal branch.
- Angular branch.
- Temporooccipital branch.
- Posterotemporal branch.
- Middle temporal branch.
What are the segments of the PCA?
P1 - precommunicating segment.
P2 - ambient segment.
P3 - quadrigeminal segment.
P4 - terminal cortical branches.
What are the branches off the P1 segment?
- Posterior thalamoperforating arteries.
- Medial posterior choroidal arteries.
- Meningeal branches.
What are the branches off the P2 segment?
- Lateral posterior choroidal artery.
- Thalamogenicular arteries.
- Cortical branches.
What are the branches off the P3 segment?
- Posterior temporal artery.
- Internal occipital artery.
- Parietooccipital artery.
- Calcarine artery.
- Posterior pericallosal artery.
Branches off the vertebral artery?
- Extracranial branches (segmental spinal branches, muscular branch anastomoses with muscular branch of ECA, and meningeal branch).
- Posterior spinal artery.
- Anterior spinal artery.
- PICA.
What is the blood supply to the falx cerebelli?
- Posterior meningeal branches.
- Occipital.
- Ascending pharyngeal.
- PICA.
Vascular territory of the posterior spinal artery?
Gracile and cuneate fasciculi, ifnerior cerebellar peduncle.
Vascular territory of the anterior spinal artery?
Pyramid, medial lemniscus, MLF, olive, vagal and hypoglossal nuclei.
What are the segments of PICA?
- Anterior medullary.
- Lateral medullary.
- Tonsillomedullary.
- Telovelotonsillar.
- Hemispheric branches.
What syndrome occurs with occlusion of PICA?
Lateral medullary syndrome (Wallenberg’s).
What are the branches off AICA?
- Internal auditory artery.
- Recurrent perforating artery.
- Subarcuate artery.
Vascular supply to the striatum?
Mainly: MCA (lenticulostriate arteries).
Rostrally: recurrent artery of Heubner.
Caudally: anterior choroidal.
Vascular supply to the internal capsule?
Anterior limb: ACA (Heubner, MCA lateral (lenticulostriate).
Genu: ICA perforators, MCA lateral (lenticulostriate)
Posterior limb: anterior choroidal and Pcomm.
Vascular supply to the thalamus?
PCA by way of posterior thalamoperforators, thalamogeniculate arteries, and the medial posterior choroidals.
Rostrally from Pcomm and basilar bifurcation.
Vascular supply to the medulla?
Anterior and posterior spinal arteries.
PICA and vertebral arteries.
Vascular supply to the pons?
Basilar paramedian branches.
Short and long circumferential branches of the basilar artery that anastomose with AICA at the middle cerebellar peduncle.
SCA.
Vascular supply to the midbrain?
Basilar artery, PCA, SCA, Pcomm, and anterior choroidal.
What is Weber’s syndrome?
CN III palsy with contralateral hemiplegia.
What is Benedikt’s syndrome?
Weber’s plus red nucleus lesion (coarse intentional tremor, hyperkinesias, and ataxia of the upper limb).
What cistern does the basal vein of Rosenthal pass through?
Ambient cistern.
Excitatory neurotransmitters.
Glutamate and aspartate.
Inhibitory neurotransmitters.
GABA.
How many layers are in the neocortex?
The neocortex has 6 layers.
How many layers are in the allocortex?
The allocortex has 3 layers, located in the olfactory cortex, hippocampus, and dentate gyrus.
What are the 6 layers in the neocortex?
I. Molecular (most superficial). II. External granular layer. III. External pyramidal layer. IV. Internal granular layer. V. Internal pyramidal layer. VI. Multiform.
What layer of the neocortex is responsible for main sensory input?
Layer IV (internal granular layer).
What layer of the neocortex has main efferents to the brainstem and spinal cord?
Layer V (internal pyramidal layer).
What layer of the neocortex has efferent fibers to the thalamus?
Layer VI (multiform layer).
Function of the premotor cortex (area 6a).
Voluntary motor control for responses dependent on sensory input.
Function of the supplemental motor cortex (area 6a).
Programming, planning, and initiation of motor movements.
Function of the frontal eye fields.
Initiates saccades - stimulation causes contralateral eye deviation.
Contents of the neostriatum (or striatum).
Caudate and putamen.
Contents of the paleostriatum.
Globus pallidus.
Contents of the corpus striatum.
Neostriatum + paleostriatum (caudate, putamen, GP).
Contents of the archistriatum.
Amygdala.
Contents of the lentiform nuclei.
Putamen and globus pallidus.
Location of lateral medullary lamina.
Between putamen and globus pallidus.
Location of medial medullary lamina.
Between medial and lateral globus pallidus.
Origin of the adenohypophysis.
Ectoderm.
Origin of the neurohypophysis.
Diencephalic.
What are the three components of the adenohypophysis?
- Pars tuberalis
- Pars intermedia.
- Pars distalis.
What are the three components of the neurohypophysis?
- Pars nervosa (posterior lobe).
- Infundibulum.
- Nuclei (supraoptic and paraventricular).
What arteries form the hypophyseal portal system?
The hypophyseal portal system is formed by the superior hypophyseal arteries (supraclinoid ICA) and the inferior hypophyseal arteries (branch of cavernous ICA meningohypophyseal trunk).
What are the cholinergic areas of the CNS?
- Substantia innominata (nucleus basalis of Meynert).
- Pedunculopontine nucleus.
- Lateral dorsal tegmental nucleus.
- Medial habenular nucleus.
What is the archicerebellum?
Oldest component which includes the flocculus and nodulus.
Involved with vestibular function.
What is the paleocerebellum?
Includes the anterior lobe, rostral to the primary fissure.
Controls muscle tone with inputs from the stretch receptors.
What is the neocerebellum?
Newest component which includes the posterior lobe between the primary fissure and the lateral fissures.
Controls coordination with inputs from the contralateral cortex (via pontine relay nuclei).
Function of dorsal spinocerebellar tract.
Uncrossed.
Conveys proprioception from the joints, muscle spindles, and Golgi tendon organs of the ipsilateral LEs and upper trunk to Clarke’s nucleus in lamina VII of the intermediate zone in the spinal cord.
Function of the ventral spinocerebellar tract.
Crossed.
Conveys efferent copies of motor commands that reach the alpha motor neurons and exteroceptive and proprioceptive information for the LEs.
What are the cerebellar nuclei and their functions.
- Fastigial nucleus - vestibular system.
- Globuse nucleus - tone.
- Emboliform nucleus - tone.
- Dentate nucleus - coordination.
What nuclei make up the nucleus interpositus?
- Globus and emboliform nuclei.
The olfactory tract carries secondary neurons to what three areas?
- Primary (lateral) olfactory area (via lateral olfactory stria).
- Anterior perforated substance (intermediate olfactory area).
- Medial olfactory area (septal area).
What structures make up the primary (lateral) olfactory area?
- Uncus.
- Entorhinal area (anteiror portion of the hippocampal gyrus).
- Limen insula (insular and frontal lobe junction).
- Part of the amygdala.
Function of the medial olfactory area?
- Located in the subcallosal region of the medial frontal lobe, this region mediates emotional responses to odors with its limbic connections.
What is the diagonal band of Broca?
- Connects all three olfactory areas.
What is von Willebrand’s knee?
- Contains fibers from the contralateral optic nerve that travel across a short distance into the other optic nerve before continuing through the optic tract.
Function of the lateral subnucleus of CN III?
- Innervates ipsilateral inferior rectus, inferior oblique, and medial rectus.
Function of the medial subnucleus of CN III?
- Innervates contralateral superior rectus.
Function of the central subnucleus of CN III?
- Innervates levator palpebrae superioris bilaterally.
CN III passes through what cistern?
- Interpeduncular cistern at the midbrain/pons junction.
What division of CN III do parasympathetic fibers travel?
- Inferior division.
Function of the mesencephalic nucleus of CN V?
- Conveys proprioceptor info from the muscles of mastication.
Function of the chief sensory nucleus of CN V?
- Conveys light touch from face.
Function of the spinal nucleus of CN V?
- Conveys pain, temperature, and deep pressure info.
Location of the abducens nucleus?
- Ventral to the 4th ventricle in the pontine tegmentum.
Motor branches of CN VII?
- Ten Zebras Bit My Clock.
Temporal, zygomatic, buccal, mandibular, cervical.
Lesion of the lateral lemniscus causes what?
- Contralateral deafness.
Unilateral damage to the superior colliculus produces what?
- Contralateral visual field neglect.
- Impaired tracking.
- NO deficit with eye movements.
What is the main function of the rostral interstitial nucleus of the MLF?
- Main center for vertical eye movement (especially downward).
What is the function of the inferior colliculus?
- Responsible for the tonotopic organization of auditory information and projects via the brachium of the inferior colliculus to the medial geniculate body.
What are some functions of the periaqueductal gray?
- Central analgesia.
- Vocalization.
- Control of reproductive behavior.
- Aggressive behavior.
- Upward gaze.
What happens when the red nucleus is stimulated?
- Increased tone in the contralateral flexors and decreased tone in the contralateral extensors.
What happens when the interposed nucleus is stimulated?
- Increased ipsilateral flexion.
What happens when the pedunculopontine nucleus is stimulated?
- Causes walking movements.
2. Controls locomotion.
What neurotransmitter is predominant in the locus ceruleus?
- NE.
What is the function of the locus ceruleus?
- Controls cortical activation and paradoxical (REM) sleep.
What are the functions of the raphe nuclei?
- Provided endogenous analgesia via the substantia gelatinosa.
- Controls deep sleep, mood, and aggression.
Features of Rexed lamina I?
- Mainly pain and temperature (fast pain, A-delta), that travel in the contralateral spinothalamic tract.
What is another term for Rexed lamina II?
- Substantia gelatinosa.
Function of Rexed lamina II?
- Slow pain (C fibers).
What is another term for rexed lamina III/IV?
- Nucleus proprius.
Function of rexed lamina III/IV?
- Contains interneurons that convey low intensity stimuli to the thalamus.
What is another term for rexed lamina VII?
- Zona intermedia.
What type of neurons are found in rexed lamina IX?
- Alpha and gamma motor neurons.
What is the function of the medial nuclear group of rexed lamina IX?
- Controls the axial muscles.
What is the function of the lateral nuclear group of rexed lamina IX?
- Controls the limbs appendicular muscles.
What is the function of the ventral nuclear group of rexed lamina IX?
- Controls extensors.
What is the function of the dorsal nuclear group of rexed lamina IX?
- Controls flexors.
Function of the posterior columns?
- Convey fine touch, vibration and proprioception.
Function of the anterior spinothalamic tract?
- Conveys mainly light touch.
Function of the lateral spinothalamic tract?
- Conveys pain and temperature.
Function of the spinotectal tract?
- May convey pain stimuli.
Function of the dorsal spinocerebellar tract?
- Conveys touch, pressure and proprioception from the lower limbs.
Function of the ventral spinocerebellar tract?
- Conveys lower limb posture and coordination information.
Function of the cuenocerebellar tract?
- Conveys touch, pressure, and proprioception from the upper limbs (upper limb equivalent of the dorsal spinocerebellar tract).
Function of the spinoreticular tract?
- Modulates motor, sensory, behavior and awareness.
Function of the corticospinal tract?
- Conveys voluntary skilled movements.
Function of the tectospinal tract?
- Conveys reflex posture movements in response to visual and possibly auditory stimuli.
Function of the rubrospinal tract?
- Involved in the maintenance of flexor tone.
Function of the vestibulospinal tract?
- Involved in the maintenance of extensor tone.
Function of the pontine reticulospinal tract?
- Involved in the maintenance of extensor tone (antigravity muscles).
- Axial (especially the neck muscles) limb muscles.
Function of the medullary reticulospinal tract?
- Involved in inhibition of extensor tone.
What tracts are involved in flexor tone?
- Lateral reticulospinal (medullary tract).
2. Rubrospinal tract (to upper limbs only).
What tracts are involved in extensor tone?
- Medial and lateral vestibulospinal tracts.
2. Medial (pontine) reticulospinal tract.
Damage to the anterior lobe of the cerebellum causes what?
- Removes tonic inhibition of the lateral vestibular nucleus resulting in increased extension.
Normal AP diameter of the spinal canal at C1-C2?
- 15 mm.
Normal AP diameter of the spinal canal at C3-T12?
- 12 mm.
Normal AP diameter of the spinal canal at L1-L5?
- 15-20 mm.
Structures within the cribiform plate?
- Olfactory nerves.
- Ethmoidal nerves.
- Ethmoidal arteries.
Structures within the optic canal?
- CN II
2. Ophthalmic artery.
Structures within the superior orbital fissure.
- CNs III, IV, and VI.
- CN V1 -all three branches (nasociliary, frontal, lacrimal).
- Sympathetic fibers from ICA plexus.
- Middle meningeal artery (orbital branch).
- Lacrimal artery (recurrent meningeal branch).
- Superior ophthalmic vein.
Structures within the inferior orbital fissure.
- CN V2.
- Zygomatic nerve.
- Maxillary nerve (pterygopalatine branch).
- Infraorbital artery and vein.
- Inferior ophtlamic vein.
Structures within the foramen rotundum.
- CN V2.
Structures within the foramen ovale.
- CN V3.
2. Lesser superficial petrosal nerve.
Structures within the foramen lacerum.
- Usually nothing, 30% with vidian artery.
2. ICA traverses upper portion.
Structures within the carotid canal.
- Sympathetic nerves.
2. ICA.
Structures within the internal acoustic meatus.
- CN VII, VIII.
2. Labyrinthine vessels.
Structures within the stylomastoid foramen.
- CN VII.
2. Stylomastoid artery.
Structures within the jugular foramen (pars nervosa).
- CN IX.
2. Jacobson’s nerve.
Structures within the jugular foramen (pars venosa).
- Posterolateral CN X, XI.
- Arnold’s nerve.
- Internal jugular vein.
- Inferior petrosal sinus.
- Posterior meningeal artery.
Structures within the hypoglossal canal.
- CN XII.
2. Posterior meningeal artery.
Structures within the foramen cecum.
- Emissary veins (SSS -> frontal sinus and nose).
- Anterior falcine artery.
Located between the frontal crest and crista galli.
Structures within the supraorbital foramen.
- CN V1.
2. Supraorbital vessels and nerve.
Structures within the infraorbital foramen.
- CN V2.
2. Infraorbital vessels and nerve.
Structures within the mandibular foramen.
- CN V3: inferior alveolar nerve.
Structures within the incisive foramen.
- CN V2: nasopalatine nerve.
2. Vessels to anterior hard palate.
Structures within the mental foramen.
- CN V3: mental nerve.
Structures within the greater palatine foramen.
- Greater palatine nerves.
- Vessels to the hard palate and gingiva.
- Located medial to the third molar.
Structures within the lesser palatine foramen.
- Lesser palatine nerves.
2. Vessels to the soft palate.
Structures within the pterygopalatine fossa.
- CN V2: maxillary nerve.
- Pterygopalatine ganglion.
- Vidian nerve.
Structures within the infratemporal fossa.
- CN V3.
- Chorda tympani nerve.
- Otic ganglion, inferior.
- Inferior alveolar nerve.
- Lingual nerve.
- Buccal nerve.
- Muscles: temporalis, medial and lateral pterygoids.
- Maxillary artery.
- Pterygoid venous plexus.
Structures within the vidian canal (pterygoid canal).
- Vidian nerve.
- Union between the greater superficial petrosal nerve (parasympathetic) and deep petrosal nerve (sympathetic).
Located at the base of medial pterygoid plate (sphenoid bone).
Connects the foramen lacerum to the pterygopalatine fossa.
Structures within the petrotympanic fissure.
- Transmits chorda tympani.
Structures within the greater petrosal foramen.
- Greater superficial petrosal nerve.
Structures within the lesser petrosal foramen.
- Lesser superficial petrosal nerve.
Description of the falciform ligament.
- Dura extending between anterior clinoid and planum sphenoidale, covering the optic nerve.
Description of Liliequist’s membrane.
- Two sleeves of arachnoid connecting the posteroinferior wall of the ICA cistern and the superior aspect of the interpeduncular cistern.
What structures pass above the annulus of Zinn?
- CN V1: lacrimal nerve.
- CN V1: frontal nerve.
- CN IV.
What structures pass through the annulus of Zinn?
- CN III: superior division.
- CN III: inferior division.
- CN VI: nasociliary nerve.
- CN VI.
What does the superior division of CN III innervate?
- Levator palpebrae superioris and superior rectus.
What does the inferior division of CN III innervate?
- Inferior rectus, medial rectus and inferior oblique.
Feature of the medial longitudinal fasciculus.
- Eye movements with vestibular input.
Feature of the dorsal longitudinal fasciculus.
- Periventricular hypothalamus and mammillary bodies to midbrain central gray.
Feature of the medial lemniscus.
- Posterior column continuation to the thalamus.
Feature of the lateral lemniscus.
- Part of the auditory pathway.
Feature of the commissure of Probst.
- Connects the nuclei of the lateral lemniscus.
Feature of the central tegmental tract.
- Connects the gustatory nucleus (rostral nucleus solitarius) to medial thalamic VPM (wakefulness).
- Connects red nucleus to inferior olive.
Feature of the medial forebrain bundle.
- Connects septal area, hypothalamus, basal olfactory areas, hippocampus/subiculum to midbrain, pons and medulla.
Feature of the lamina terminalis.
- Closed rostral end of the neural tube.
Feature of the stria terminalis.
- Connects amygdala to hypothalamus.
Feature of the stria medullaris.
- Connects the septal area, hypothalamus, olfactory area and anterior thalamus to habenulum.
Feature of the fornix.
- Connects hippocampus to:
A. Pre-commissural - septal nuclei, hypothalamus, mammillary bodies, an anterior thalamus.
B. Post-commissural - cingulate gyrus.