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160 Cards in this Set
- Front
- Back
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Midbrain Cranial Nerves
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III and IV
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Pons cranial nerves
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V, VI, VII, VIII
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Medulla Cranial Nerves
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IX, X, XII
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Sensory/Motor cranial nerve distribution in Brainstem
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Medial: motor
Lateral: sensory |
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Position of Medial Lemniscus in Brainstem
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Moves from medial to lateral as it ascends
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Position of Anterolateral System in the brainstem
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Courses laterally throughout
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Position of Descending hypothalamic fibers in brainstem
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Courses laterally with the spinothalamic tract
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Medial Longitudinal Fasciculus
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Links ocular cranial nerve nuclei and vestibular nuclei
Courses medially and ventrally susceptible to MS |
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Components of every brainstem section
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1. Corticospinal Tract
2. DCML 3. Spinothalamic/descending hypothalamic tract 4. Medial Longitudinal Fasciculs 5. Central Tegmental Tract 6. Cranial Nerve nucleus or nerve 7. A trigeminal nucleus 8. Cerebellar peduncle |
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Corticalbulbar Innervation
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UMNs of the cranial nerves
Bilateral Exception: UMNs to muscles of nose and mouth are contralateral only |
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Facial Nerve UMN lesion
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Droopy lip
Can't flare nose Can still wrinkle forehead |
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Facial Nerve LMN lesion
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Droopy lip
Can't flare nose Can't wrinkle forehead |
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Sulcus limitans
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Separation between sensory and motor neurons in neural tube and spinal cord
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3 columns of motor nuclei in brainstem
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medial-most: somatic
visceral (parasympathetic) lateral-most: branchial |
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Somatic Motor Nuclei of brainstem
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Oculomotor Nucleus
Trochlear Nucleus Abducens Nucleus Hypoglossal Nucleus |
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Midbrain Cranial Nerve Nuclei
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Oculomotor Nucleus
Edinger-Westphal Nucleus Trochlear Nucleus Mesencephalic Nucleus |
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Pons Cranial Nerve Nuclei
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Abducens Nucleus
Superior Salivatory Nucleus Motor Trigeminal Nucleus Motor Facial Nucleus Principle Sensory Nucleus of V Spinal Trigeminal Nucleus |
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Medulla Cranial Nerve Nuclei
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Hypoglossal Nucleus
Dorsal Motor Nucleus of Vagus Inferior Salivatory Nucleus Nucleus Ambiguus Solitary Nucleus Vestibular Nuclei Cochlear Nucleus Spinal Trigeminal Nucleus |
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Parasympathetic Cranial Nerve Nuclei
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Nucleus of Edinger Westphal
Superior Salivatory Nucleus Inferior Salivatory Nucleus Dorsal Motor Nucleus |
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Edinger Westphal Nucleus
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Pregang parasym. axons that synapse in ciliary ganglion
Motor limb of light and accommodation reflex |
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Superior Salivatory Nucleus
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Pregang. parasymp. axons in CN VII that synapse in submandibular ganglion
Innervate submandibular and sublingual glands Those that synapse in pterygopalatine ganglion innervate oral and nasal mucous glands and lacrimal gland |
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Inferior Salivatory Nucleus
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Pregang. Parasym. that course with CN IX and synapse in otic ganglion to parotid gland
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Dorsal Motor Nucleus
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Pregang. parasymp. that course with CN X that synapse in the gut
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Motor Nucleus of V
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muscles of mastication
lesion causes protrusion of jaw toward lesion |
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Motor Nucleus of VII
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Muscles of Facial Expression
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Nucleus Ambiguus
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LMNs of CN IX and X
some parasympathetic to heart lesion: uvula deviates away |
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Solitary Nucleus
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Rostral: receives taste fibers from VII, IX, and X, and relays to thalamus
Caudal: cardiorespiratory center, carotid sinus, carotid body (IX and X) |
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Superior Olivary Nuclei
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receive CN VIII bilaterally to locate sound source
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Mesencephalic Nucleus
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CN V, proprioception of jaw muscles
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Principle Nucleus
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CN V, responds to touch sensation
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Spinal Nucleus
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CN V, repsonds to pain and temperature
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Thalamic Relay for Corticobulbar axons
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Ventral Posterior Medial Nucleus
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Superior Cerebellar Peduncle
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Axons from the deep cerebellar nuclei out of cerebellum
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Middle Cerebellar Peduncle
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Axons from pontine nuclei into cerebellum
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Inferior Cerebellar Peduncle
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axons into cerebellum from spinal cord and brainstem and out of cerebellum from deep cerebellar nuclei
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Internal Medullary Lamina (IML)
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Curved sheet of myelinated fibers that divide thalamus into medial, lateral, anterior, and internal groups of nuclei
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Relay vs. Association Circuits
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Both in Thalamus
Relay: sensory, motor, or limbic Association: serve as shortcut btwn brain areas parietal-occipital-temporal, and prefrontal |
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VPM
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Corticobulbar relay for sensory input
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VPL
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Corticospinal relay for sensory input in thalamus
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Mediodorsal Nucleus
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Association circuits
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Centrum Medianum
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Intralaminar nuclei, produce nonspecific changes in brain state
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Cortex classifications
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Neocortex: 95%
Paleocortex: olfaction Archicortex: hippocampus |
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Cortex layers
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1. molecular layer
2. external granular layer 3. External pyramidal layer 4. Internal Granular layer 5. Internal pyramidal layer 6. multiform layer |
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Motor Cortex layers
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lots of pyramidal cells
fewer granular cells |
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Sensory Cortex layers
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lots of granular cells
fewer pyramidal cells |
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Cortex Columnar Organization
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Organized functionally by column
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Functions of Cortical Layers
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Layer 4: input
Layers 1-3: cortico-cortico communication Layers 5-6: subcortical connections |
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Axonal Neuropathy
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decreased amplitude of distal and proximal action potentials
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Uniform Demyelinating Neuropathy
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Normal sized distal and proximal action potentials
Slow conduction velocity |
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Normal AP speed
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50 m/sec
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Repetitive Electromyogram
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used to diagnose NMJ disorders (decreased amplitude of action potentials over time)
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Abnormal Electormyograms
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Amplitude too big: neuropathic
Amplitude too small: myopathic |
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Electroencephalogram (EEG)
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recording brain's electrical activity from the scalp surface
Reflects extracellular currents from large numbers of cortical neurons |
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Sleep stages
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Stage 1: eyes move
Stage 2: synchrony Stage 3: some delta waves Stage 4: deep sleep, all delta waves REM: dreams, muscle atonia |
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Wake-to-sleep Transition
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hypothalamic switch to rhythmic spikes independent of stimuli
cell hyperpolarization |
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T Channels in Hypothalamus
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Calcium channels activated by hyperpolarized thalamus. Cause rhythmic depolarization of thalamus
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Arousal Systems
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Norepinephrine: locus coeruleus
Serotonin: raphe nuclei Dopamine: ventral tegmental area Acetylcholine: septal nuclei |
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Feedforward Control of Voluntary Movement
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Essential for Rapid Action
Depends on Ability to Predict Can Modify Feedback Mechanisms |
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Long and Short Proprioceptive Interneurons (in spinal cord)
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Long: control posture
Short: control distal elements |
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Primary Motor Cortex Activity
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Related to muscle force, not to movement amplitude
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Primary Motor Cortex
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Specific parameters of movement
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Superior Motor Area
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Specific order of responses
Internally generated plan Based on Memory |
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Lateral Premotor Cortex
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Used in trained movements, sensory motor integration
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General Cerebellar Role
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Evaluate and correct disparities between intention and action of movement
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Folium
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Fold of the cerebellum
Layers: molecular, purkinje, granular, white matter |
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Mossy fiber pathway through cerebellum
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mossy fiber -> granule cell ->weak synapse with purkinje cells -| deep cerebellar nuclei
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Climbing fiber pathway
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inferior olive -> strong synapse with 5-7 purkinje cells -| deep cerebellar nuclei
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Purkinje cells
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dendrites oriented perpendicular to parallel fibers. Receive millions of parallel fiber inputs
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Spinocerebellum
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medial part of cerebellum. Receives spinal and trigeminal inputs.
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Cerebrocerebellum
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lateral hemispheres of cerebellum Receive corticopontine inputs
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Vestibulocerebellum
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flocconodular lobe. Receives vestibular inputs. Only lobe in which purkinje cells project out of cerebellum.
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Fastigial Nuclei
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most medial nuclei in cerebellum
bilateral posture, locomotion, and gaze |
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Interposed nuclei
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bilateral posture, locomotion, and gaze
Rubrospinal tract |
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Dentate Nucleus
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Most lateral cerebellar nucleus.
Motor planning and mental rehearsal Sends axons contralaterally in order to control ipsilateral limbs |
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Basal Ganglia function
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Modulate movement, cognition, and behavior
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Basal Ganglia components
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Striatum (caudate and putamen)
Pallidum (globus pallidus interna and externa) Substantia Nigra (pars compacta and reticularis) Subthalamic nucleus |
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Striatum
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Receives input from cortex for use in basal ganglia
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Pallidum
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the globus pallidus interna and externa
Receives striatal output |
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Subthalamic Nucleus
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part of basal ganglia that modulate globus pallidus externa and interna
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Substantia Nigra
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Pars compacta: dopaminergic neurons to striatum
Pars reticularis: receives striatum output in direct pathway |
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Parkinson Features
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Bradykinesia - slow initiation of movement
Rigidity Resting Tremor Stooped and unstable posture Cogwheel movement |
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Huntington's disease
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Loss of GABAergic neurons of striatum
Loss of indirect pathway |
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Huntington's symptoms
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Chorea
Athetosis: slow, writhing movements Mental decline and personality changes |
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Motor System Functions
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Brainstem/Cerebellum: coordination and balance
Pyramidal System: strength, voluntary movement Basal Ganglia: posture, speed, tone |
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Loss of Brainstem/Cerebellum motor control
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Ataxia
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L-dopa
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drug for Parkinson's Metabolic precursor that can cross blood-brain barrier. Prescribed with a DDC and MAOI to prevent peripheral breakdown
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Hypokinetic movement disorders
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Parkinson's
Parkinsonian Syndromes wilson's disease Dementias |
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Parkinson's vs. Essential Tremor
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PD: asymmetrical, greater at rest, small handwriting, parkinson symptoms
ET: symmetric, greater during motion, shaky handwriting |
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Hemiballismus
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Severe chorea affected the whole body
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Myoclonus
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shock-like jerks, with fast and slow phase
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Tic
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Abrupt, brief, forewarned and suppressible movement
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Dystonia
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sustained muscle contractions with twisting postures
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Lewy Bodies
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aggregations of alpha-synuclein in neurons
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Atypical Parkinsonian Syndromes
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Multiple systems atrophy (autonomic failure)
Progressive supranuclear palsy (surprised expression) Corticobasal degeneration Wilson's disease (young onset) |
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Levodopa dyskinesia
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Chorea caused by super-physiologic doses of L-dopa
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Anticipatory Postural Control
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Reticulospinal Tract
Vestibulospinal Tract Uncrossed Corticospinal tract |
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Red Nucleus
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origin of the rubrospinal tract in the midbrain
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Neural Control of Locomotion
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Descending control: reticulospinal projections
Spinal: Central Pattern Generator |
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Mesencephalic Locomotor Region
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Triggers an episode of walking by activating reticulospinal tract which activates the CPG
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Speed of Locomotion
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Relative to stimulus intensity
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CPG location
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Medial aspect of intermediate zone
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Free nerve ending receptor modalities
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Pain, temperature, and crude touch
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Pacinian Corpuscle Modalities
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Deep pressure and vibration. Rapidly adapting -> sends on/off signals
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Anoxia nerve sensitivity
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Big axons are lost first
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Anesthesia nerve sensitivity
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Small axons respond first
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Function of nerve lateral inhibition
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Contrast enhancement
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vestibulocerebellum
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Flocculonodular lobe
Input: vestibular labrynth Output: Vestibulospinal tract, MLF Function: posture, balance |
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Cerebellar Disease
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ATAXIA - incoordination
Decomposition of movement Midline cerebellar problems cause midline muscular problems |
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Titubations
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Trunkal tremor
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Corticopontalcerebellum
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dentate nucleus and lateral hemispheres
Input: cortical afferents Output: motor and premotor cortex Function: complex distal limb movements, planning |
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Dysdiadochokinesis
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impairment in executing rapid alternating movements
test by tapping each finger to thumb |
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Horizontal Nystagmus
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jerky horizontal eye movements
characteristic of cerebellar dysfunction |
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Ataxic Dysarthria
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Disruption of metrical structure of speech
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Tone
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resistance to passive movement
typical transient hypotonia w/ acute cerebellar damage |
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Cerebellar vs. Sensory Ataxia
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Sensory: Romberg's sign
ex. tabes dorsalis Cerebellar: abnormal gait and titubation |
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vestibular dysfunction
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Causes vertigo
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Cerebellar Vasculature
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SCA: all 3 nuclei, SCP, MCP
AICA: lateral interior regions, flocculus PICA: medial interior regions, nodulus |
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Posterior Fossa Tumors
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More common in children than adults
Affects cerebellum |
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Chiari I malformation
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Caudal displacement of the cerebellar tonsils below the foramen magnum
Asymptomatic or headaches |
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Chiari II and III malformations
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due to neural tube defects
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Dandy Walker Malformation
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cystlike dilation of 4th ventricle, cerebellar vermis absent
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Joubert Syndrome
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Molar tooth sign on imaging
Cerebellar dysfunction |
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Post-infectious cerebellitis
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post-infectious inflammation of cerebellum
Usually in children under 5 hyperacute onset of symptoms, and eventual resolution |
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Cerebellar toxicity
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Due to alcohol intake or phenytoin
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Middle cerebral artery
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supplies lateral hemisphere
occlusion: contralateral hemiparesis. L side: language deficit, R side: neglect |
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Anterior Cerebral Artery
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supplies Medial cortical structures. Occlusion: contralateral lower extremity weakness
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Basilar Artery
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supplies occipital lobe
Occlusion: oculomotor deficits and/or ataxia |
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Weber Syndrome
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Occlusion distally in basilar artery damaging brainstem. Causes ipsilateral CN III palsy w/ contralateral hemiparesis
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Locked In Syndrome
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Occlusion of proximal midbasilar artery infarcts the pons. Damage to ventral pons causes loss of all motor pathways w/out affecting cognition
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Wallenberg's syndrome
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Occlusion of PICA. ipsilateral horner's syndrome and facial sensory loss, contralateral sensory loss
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ACA occlusion
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contralateral leg weakness
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MCA occlusion
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contralateral face and arm weakness, sensory loss, field cut, neglect
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PCA occlusion
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contralateral field cut
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Lacunar occlusion
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Contralateral motor or sensory deficit without cortical signs
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Basilar artery occlusion
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Oculomotor deficits and/or ataxia w/ crossed sensory and motor deficits
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Vertebral artery occlusion
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lower cranial nerve deficits and/or ataxia with crossed sensory deficits
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Acute Cerebrovascular Events
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Ischemic stroke (80%)
Hemorrhagic stroke (20%) |
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Subarachnoid Hemorrhage
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due to ruptured macrovascular artery into subarachnoid space
Blood everywhere on MRI WHOL, bloody/xanthochromic CSF |
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Aneurysm locations
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at vascular brach points
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Subarachnoid Hemorrhage Complications and Treatment
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Complications: rebleeding, vasospasm, hydrocephalus
Treatment: clipping or coiling, minodipine |
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Nimodipine
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Calcium channel blocker, prevents vasospasms
Used after aneurysm treatment |
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Arterial Venous Malformation
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direct connection of artery to vein
prone to rupture (Nate Fisher) |
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Intracerebral Hemorrhage
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Localized bleed into brain parenchyma
CT scan nails it Caused by hypertension |
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Cerebral Amyloid Angiopathy
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Collection of amyloid in cerebral vessels
Causes ICH in elderly, often multifocal |
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Red Nuclei location
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In the Midbrain, dorsal to the substantia nigra
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Pupillary Light Reflex
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tests cranial nerves II and III, integrity of midbrain
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Blink Reflex
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tests cranial nerves V and VII, integrity of pons
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Vestibular-ocular reflex
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"Dolls' eyes"
tests CN VIII, VI, and III tells us about MLF |
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Blood supply to medulla
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PICA supplies lateral portion
Vertebral artery supplies medial section |
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Internuclear opthalmoplegia
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inability to adduct the eye
Bilateral INO is often first symptom of MS due to MLF degeneration |
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Worst Headache of Life + blown pupil w/out trauma
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aneurysm
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Blown pupil with trauma
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Herniation of unci. Very life-threatening
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Wernickes Disease
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B1 deficiency leading to sixth nerve palsy
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Wallenberg Syndrome
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affects CN V, IX, and X
Medular ischemia |
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Olfactory System anatomy
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Olfactory bulb -> olfactory tract -> pyriform cortex (uncus) and amygdala
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Olfactory signal transduction
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GPCR -> Golf -> AC -> cAMP -> open Na and Ca influx channels and Cl efflux channels -> depolarization
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Olfactory population coding
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Odor quality and intensity are encoded by combinations of receptors
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Olfactory bulb composition
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Mitral cells form Glomeruli receive inputs from epithelium
Periglomerular cells modulate inputs Granule cells modulate outputs |
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Salty and Sour sensation
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mediated via ion channels in taste bud epithelial cells
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Sweet, Umami, and bitter sensation
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mediated by GPCRs in taste bud epithelial cells
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