week 2- neuro Flashcards
• BRAIN =
o Cerebrum, Cerebellum, Brain Stem
• Cerebrum=
o 2 hemispheres: R & L
o 4 lobes: frontal, parietal, temporal, occipital
• Frontal Lobe=
o principal speech area: Broca’s, motor component of speech
o primary motor area (precentral gyrus): motor homunculus (inverted human: HAL)
• Parietal Lobe=
o primary sensory area (postcentral gyrus): sensory homunculus
o Major association areas located where lobes meet
• Temporal and occipital lobes:
o T: auditory area, hearing, superior temporal gyrus; Language: Wernicke’s area: sensory component of speech
o O: vision: primary visual cortex
• other subdivisions of cerebrum:
o gyri (bulges) o fissures (large indentations) o sulci (small indentations)
• Cerebellum:
o 2 hemispheres, cortex of gray matter on surface, central masses of motor related nuclei, bands of white matter
o attached to brain stem by 3 cerebellar peduncles
o fxn: equilibrium and position sense (unconscious proprioception); fine movement; control of muscle tone; overall coordination of muscular activity for proprioception, descending traffic from higher centers
o Spinocerebellar tract: receives afferent info from periphery; Tracts come from same side and do not cross
• Cerebellar Disorders:
o Ataxia: awkwardness of posture and gait
o ↓ tendon reflexes on affected side
o Asthenia: muscles tire easily
o Tremor: usu intention tremor (w purposeful movt)
o Nystagmus
• Brain stem:
o 3 parts: Midbrain, Pons, Medulla
o Most CNs (except I, II) derived from brain stem (12 pair); 3 sensory, 5 motor, 4 mixed; (CNs actually considered part of PNS)
• CNs:
o Olfactory (I); sensory; smells o Optic (II); sensory; sees o Oculomotor (III); motor; constricts pupil, accommodates o Trochlear (IV); motor; moves eyes o Trigeminal (V); mixed; chews and feels front of head o Abducens (VI); motor; moves eyes o Facial (VII); mixed; moves the face, tastes, salivates, cries o Vestibulocochlear (VIII); sensory; hears, regulates balance o Glossopharyngeal (IX); mixed; tastes, salivates, swallows, monitors carotid body and sinus o Vagus (X); mixed; tastes, swallows, lifts palate, talks, communication to and from thoraco-abdominal viscera o Spinal Accessory (XI); motor; turns head, lifts shoulder o Hypoglossal (XII) motor; moves tongue
• Spinal cord:
o enters skull thru foramen magnum to become brain stem
o Central gray matter (neuronal cell bodies and synapses)
o Peripheral white matter (ascending and descending pathways)
o Ascending pathways: sensory info to brain
o Descending pathways: motor instructions down from brain
o Sites of contralateral crossing over of pathways within the white matter is important clinically
• Tracts of spinal cord:
o Ascending (sensory): Pain-temperature, Proprioception: stereognosis, Light Touch o Descending (motor)
• Ascending tracts:
o Spinothalamic, posterior columns, spinocerebellar
• Spinothalamic Tract
o Pain-temperature, some light touch
o Crosses over to other side of spinal cord almost immediately → ascends to thalamus and cerebral cortex on that opposite side
o → a lesion in spinothalamic tract → loss of pain-temperature sensation contralaterally, below level of lesion
• Posterior Columns:
o conscious Proprioception/stereognosis, vibration, and some light touch
o 2 columns: fasciculus gracilis, fasciculus cuneatus.
o Initially remains on same side of spinal cord. Crosses over at junction of spinal cord and brain stem
• Spinocerebellar
o unconscious proprioception
o Does not cross spinal cord
o Ipsilateral sxs
• Descending Tracts (Motor)
o =Corticospinal Pathway
o Extends from motor area of cerebral cortex down thru brain stem, crossing over at medial lemniscus (junction bw brain and spinal cord)
o Synapses in anterior horn (motor grey matter) of spinal cord just prior to leaving cord
o Upper Motor Neuron (UMN): pathway from brain to spinal cord before synapse
o Lower Motor Neuron (LMN): postsynaptic pathway from spinal cord to periphery (peripheral nerve)
• Diencephalon
o = all the structures w “thalamus” = thalamus, hypothalamus, epithalamus, subthalamus
o Thalamus: Sensory relay and integrative center connects many areas of brain: cerebral cortex, basal ganglia, hypothalamus, brain stem; All sensory pathways synapse in thalamus, then relayed
o Hypothalamus: Contains a few nuclei w variety of functions; Produces hormones that control: body temp, hunger, moods, release of hormones from many glands: pituitary, sex drive, sleep, thirst
o Epithalamus: Main part is pineal gland
o Subthalamus
• Basal ganglia
o Part of base of brain, 3 clusters of neurons (caudate nucleus, putamen, globus pallidus), responsible for involuntary movements: tremors, athetosis, chorea
• Disorders of Basal Ganglia
o Parkinsonism: rigidity; slowness; resting tremor; mask-like facies; shuffling gait, assoc w degeneration in basal ganglia, substantia nigra
o Chorea: sudden, jerky, purposeless movements
o Athetosis: slow writhing, snake-like movements, esp. fingers and wrists
o Hemiballismus: sudden wild flail-like movt of one arm
• Basic Functional Unit of CNS:
o neuron: Info travels down dendrite into neuronal cell body and axon; Information shared bw neurons thru synapses
o pathway= chain of communicating neurons. In CNS a bundle of pathway axons= a tract, fasciculus, peduncle, or lemniscus; Outside CNS (peripheral nerves, which connect CNS with skin, muscles, other organ systems) a bundle of pathway axons = nerves
• Blood Supply to brain
o 2 main pairs of arteries supply brain
o 2 internal carotid: supply anterior cerebrum: become anterior cerebral a and middle cerebral a
o 2 vertebral arteries: supply posterior cerebrum (vertebral artery changes its name to → Basilar at level of Pons → Posterior Cerebral Artery at Cerebrum)
• Meninges
o PAD surrounds entire CNS including spinal cord and optic nerve
o Pia mater: thin and vascular, closest to tbrain
o Arachnoid: avascular
o Dura: thick, double layer of CT contiguous w bone with thick venous channels. Dips down bw cerebral hemispheres as false cerebri, bw cerebrum and cerebellum as tentorium cerebelli
• Sinuses
o Superior Sagittal Sinus: Spinal fluid drains here
o Cavernous Sinus: Drains eye; potential source into brain of infx from eye or face
o Transverse Sinus: Runs by ear: may become involved in inner ear infx
• CSF
o Clear colorless fluid secreted by choroid plexus into ventricles
• General Organization of PNS
o Spinal Nerves (31 pair)
o Somatic Nervous System: Voluntary control of body via skeletal muscles
o Autonomic or Visceral Nervous System: parasympathetic and sympathetic
• Parasympathetic Division
o Synapse very close to or within their end organs
o Anabolic system, conserving energy: Slows heart rate, promotes absorption and digestion of food
o CN 3,7, 9, 10 have parasympathetic components
o CN3: ciliary body of iris→ constriction
o CN7: lacrimal, submandibular, sublingual glands → tearing, salivation
o CN9: parotid → salivation
o CN10: many organs (lungs, heart, stomach, intestines)
• Sympathetic Division:
o Motor fibers synapse relatively near spinal cord
o catabolic system, expending energy: fight or flight response to danger
o ↑ HR and contractility of heart, shunting blood to muscles and heart
• Neurologic Approach to the Patient
o Stepwise Approach: o Where is the lesion? o What is the lesion? o Identify pathophysiology o Generate DDx o Select specific tests
• Where is the lesion?
o Location of the lesion(s) causing sxs
o One lesion or multifocal? Multifocal implies metastatic dz, MS, presence of 2 different dzs, malingering, hysteria
o Confined to nervous system or part of systemic do?
o What part of nervous system is affected? Peripheral nerves, spinal cord, brainstem, higher
• What is the lesion?
o Tumor, Infection, Hemorrhage?
• History
o Essential in order to localize sxs
o May need family member/support person to help corroborate hx
o PHx, FHx, Meds, allergies, environmental exposures, SHx, ROS
• PHx
o Cardio- HTN? CVD? o Neuro- Stroke? TIAs? Psychiatric illness? o Endocrine- DM? o Hepatobiliary- Liver dz? o Trauma- TBI? Concussions? MVAs? o Overall Systemic- CA hx?
• FHx, SHx
o F: Hx of AD? PD? CVD?
o S: Smoking? ETOH? Drugs? Sexual hx (risk for neurosyphilis?); Diet (gluten?); Hobbies (exposure to heavy metals, solvents)
• ROS
o Pain? HEENT- Headache? Visual changes? Dizziness
o Neuro- Tremor? Weakness or sensory loss? LOC? Motor dysfunction. Speech or swallowing concern
• Exams:
o MSE o CNs o Motor system o Coordination, stance, gait o Sensory testing o Reflex testing
• MSE:
o FOGS; Mini Mental Status Exam (MMSE) or Montreal Cognitive Assessment (MoCA)
o Family Story of Memory Loss
o Orientation: To precise time (month, day, year)
o General Information: e.g. Who are president and vice president of the U.S.?
o Spelling: spell “WORLD” forwards and backward. Forward establishes pt can spell; backward establishes organic mental syndrome, degree further established if pt unable to spell the 5-letter word by attempting 4, 3-letter words (e.g. “HAND”, “CAT”)
