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Neuro
| Question | Answer |
|---|---|
| CNS | -Brain -Spinal Cord |
| PNS | -Cranial Nerves -Spinal Nerves -Ganglia |
| Composition of cortical surface | -Gray Matter -Neuron Cell Bodies -Dendrites -Ganglia |
| Gray matter layer | 2-4 mm thick |
| White Matter | Myelinated axons |
| Dominant Hemisphere | Left Hemisphere |
| Left hemisphere | -Written/Spoken Language -Numerical/Scientific Skills -Ability to understand sign language -Reasoning |
| Right Hemisphere | -Music/Artistic Awareness -Space/Pattern perception -Recognition of faces & emotional content in facial expression -Generate emotional content in language -Generate mental images to compare spatial relationships |
| Wernicke's Area | 22 |
| Broca's Area | 44, 45 |
| Frontal Eye Field | 8 |
| Primary Motor Gyrus | 4 |
| Primary sensory Gyrus | 1, 2, 3 |
| Primary Visual Field | 17 |
| CN 1 | Olfactory |
| CN 2 | Optic |
| CN 3 | Occulomotor |
| CN 4 | Trochlear |
| CN 5 | Trigeminal |
| CN 6 | Abducens |
| CN 7 | Facial |
| CN 8 | Vestibulocochlear |
| CN 9 | Glossopharyngeal |
| CN 10 | Vagus |
| CN 11 | Accessory |
| CN 12 | Hypoglossal |
| three layers of connective tissue called the meninges that protect and isolate the CNS from the rest of the body | pia, arachnoid, dura |
| strong elastic covering which supports the brain, separates the two hemispheres from each otherand from underlying structures | dura |
| Falx cerebri Tentorium cerebelli | dura |
| CSF production | -in choroid plexus of ventricles,does not recirculate and cleans out, drains into subarachnoid space and finally in venous system as blood |
| Transtentorial herniation | kind of herniation can lead to Duret hemorrhages, due to ‘stretching’ of arteries |
| If CSF blockage | hydrocephalus |
| Most common place for compression and obstruction of CSF? | cerebral aqueduct (longest, narrowest) |
| Amount of CSF produced | 500ml/day |
| hydrocephalus can occur due to | blockage, increased production, or decreased re-absorption |
| Blood is supplied to the brain through four main arteries | 2 internal carotid arteries and 2vertebral arteries |
| berry aneurysms | -arise from weak spots on arterial walls that ‘balloon’ out, 90% of berry aneurysms are found in the circle of Willis |
| Subdural hematoma | Results from damage to the superior cerebral veins from a blow to back or front of head. |
| Telencephalon | Cerebral hemispheres, lateral ventricles and basal ganglia. |
| Diencephalon | Thalamus, hypothalamus, third ventricle |
| Mesencephalon | midbrain |
| Metencephalon | Pons and cerebellum |
| Myelencephalon | Medulla & 4th ventricle |
| telencephalon and diencephalon together are called | prosencephalon |
| metencephalon and myelencephalon are known as the | rhombencephalon |
| brainstem consists of three parts | midbrain, pons , medulla oblongata |
| cerebellum | planning and execution of skilled motor movements and balance, 50% of neurons are here |
| Brainstem damage often characterized by | ipsilateral cranial nerve deficits, and contralateral body deficits |
| Brainstem contains reticular formation | area critical in regulating levels of consciousness. Damage- coma. |
| Cerebellum | Coordinates voluntary movement and balance |
| A fracture of the anterior cranial fossa (ie. a blow to the front of the head) usually results in damage or fracture of the cribriform plate of the ethmoid bone,leading to | epistaxis (bleeding from the nose), cerebrospinal rhinorrhea (leakage of CSF into the nose), anosmia (loss of sense of smell) |
| Unipolar | One axon, no dendrites, occur during development, NOT IN ADULTS |
| Pseudounipolar neuron | Sensory, : One single ‘process’, distal portion is from periphery to cell body, central portion is from cell body to CNS. All 1st order neurons in spinal cord are of this type, and most 1st order cranial nerves |
| Bipolar | One axon, one dendrite. CN’s I, II, VIII |
| Multipolar | Motor, Everything else |
| Golgi Type I | Long axons, dopamine axons |
| Golgi Type II | Short axons |
| Three functional types of neurons | Motor neurons, Sensory neurons, Interneurons |
| Lipofuscin granules | more abundant in older peeps cuz brain is older—marker for aging |
| Neuromelanin | (melanin) |
| Lewy bodies | (Parkinson’s) |
| Hirano bodies | (Alzheimer’s) |
| Pick bodies | ( Pick’s) |
| Negri bodies | (Rabies) |
| Cowdry type A bodies | (herpes Encephalitis) |
| Lafora bodies | (seizure disorders) |
| Pick’s disease | characterized by frontal lobe atrophy |
| Alpha motor neurons | ventral horn, innervate extrafusal muscle fibers |
| Gamma motor neurons | ventral horn, innervate intrafusal muscle fibers |
| Preganglionic Autonomic Fibers | Myelinated |
| Postganglionic Autonomic Fibers | Unmyelinated |
| Sensory Ia | Proprioception, muscle spindles |
| Sensory Ib | Proprioception, Golgi tendon organs |
| Sensory II | Touch,Pressure, Vibration |
| Sensory III | Touch,Pressure, Fast Pain, Temp |
| Sensory IV | Slow Pain, Temp: Unmyelinated fibers |
| Fast axonal transport | 200-400mm/day. |
| Slow axonal transport | 1-5mm/day. |
| Fast retrograde transport | 100-200mm/day. |
| Anterograde | KINESIN , transports vesicles and proteins |
| Retrograde | DYNEIN, transports recycled membrane and lysosomes. Certain diseases/viruses utilize retrograde transport to access the cell body (polio, herpes and rabies for ex). |
| Regeneratable Nerves | PNS, due to the arrangements of Schwann cells and the basement membrane |
| Chromatolysis | The nucleus moves away from the region of the axon hillock, and Nissl substance moves to periphery after cell damage. |
| Some cells do not recover after injury and may show a process called Neuronophagia | microglia cover the affected neuron. Common after viral infection. |
| Types of Glial Cells | Astrocytes, Ependymas, Oligodendrocytes, Microglia |
| Glial Cells provide | structure and support for neurons, produce CSF, assist in forming the blood brain barrier, form scars for healing, and myelinate neurons. |
| Two types of supporting tissues | fibrous connective & glial. |
| Supporting Tissue in PNS | fibrous connective |
| Supporting Tissue in CNS | Glial but meninges are fibrous tissue |
| falx cerebri | vertical partition residing in the longitudinal fissure between the two cerebral hemispheres |
| tentorium cerebelli | separates the cerebrum from the cerebellum (or put another way, separates the supratentorial compartment from the infratentorial compartment) |
| falx cerebelli | Small partition which separates the cerebellar hemispheres |
| diaphragma sellae | covers pituitary fossa |
| Supratentorial compartment | Everything superior to the tentorium cerebella, Includes both cerebral hemispheres (70% adult tumors supratentorial ) |
| Infratentorial compartment | Everything inferior to the tentorium cerebelli , includes brainstem and cerebellum (70% childhood tumors infratentorial) |
| Tentorial herniation (uncal herniation) | the uncus is displaced over the edge of the cerebellar tentorium (sudden onset weakness or paralysis in other side of the body…1 symptom= pupil dilation) |
| Subfalcine herniation | the cinggulate gyrus is displaced under the falx cerebri |
| Tonsillar herniation | the cerebellar tonsils are displalced into the foramen magnum |
| Two major dural sinuses in which cerebral veins empty | Superior sagittal sinus & Inferior sagittal sinus |
| Venous sinus thrombosis | Causes: Head injury, infection, prothrombotic agents, Increased risk associated with oral contraceptive use , Unlike stroke, most often affects young adults and children, Symptoms: ¾ patients present with thundercap headache as presenting sign |
| Cavernous sinus thrombosis | caused infection of paranasal (ethmoid & sphenoid) sinuses, the orbit, or the face…May involve structures passing thru sinus: Internal carotid artery, Cranial nerves III, IV, VI as well as V1 and V2 Paralysis of these nerves may result |
| Epidural hematoma is associated w/which artery? | middle meningeal artery- branch of maxillary artery (Enters middle cranial fossa via foramen spinosum ) |
| Epidural Hematoma | Patients often experience a “lucid interval” before deteriorating further, (boundaries restricted by dural sutures), lentiform shape |
| Edema’s that occur in cerebral vein thrombosis? | CYTOTOXIC & VASOGENIC |
| CYTOTOXIC Edema | caused by ischemia, damages energy dep. cellular membrane pumps, leads to intracellular swelling |
| VASOGENIC Edema | caused by disruption in blood–brain barrier & leakage of blood plasma into interstitial space, reversible if underlying condition is treated successfully |
| subdural hematoma | due to tearing of cerebral veins as they penetrate the arachnoid to drain into a dural sinus…Slower build up because pressure in veins less than in meningeal artery (epidural)--can spread very widely |
| only structure inside the cranium that is sensitive to pain | dura |
| Nerve supply to supratentorial dura | trigeminal nerve |
| Nerve supply to infratentorial dura | vagus and C1- C3 |
| Leptomeninges | arachnoid and pia |
| Subarachnoid cisterns are large regions of subarachnoid space | cisterna magna , pontine cistern, interpeduncular cistern, superior cistern |
| Subarachnoid hemorrhage | Traumatic brain injury, Rupture of aneurysm, Spontaneous bleeding from cerebral arteries (very often preceded by what patients refer to as the worst headache of their life) |
| Spinal dura mater consists of a single layer | the meningeal layer , ends at S2 vertebral level forming filum terminale externum which anchors dura to coccygeal tip |
| Spinal Pia mater | Pia mater of spinal cord is thicker than that of cranium ,Forms dentate ligaments which extend from spinal cord surface to arachnoid and dura ( help to suspend and anchor the spinal cord within the meninges ) |
| Dandy Walker syndrome | partial or complete absence of the part of the brain located between the two cerebellar hemispheres (cerebral vermis), enlargement of the 4th ventricle |
| ventricular dilation | cuz excessive CSF, observed in degenerative disorders affecting the brain, such as alzheimer’s disease |
| Ventricular shift | midline in response to masses, tumors, pools of blood, etc. |
| communicating hydrocephalus | caused by obstruction in the subarachnoid space or by impaired reabsorption by arachnoid granulations |
| Non-communicating hydrocephalus | caused by obstruction of flow within the ventricular system |
| Normal pressure hydrocephalus | occurs due to gradual blockage of the CSF drainage pathways in the brain, Ventricles enlarge but CSF pressure remains normal..Characterized by the triad of: Dementia, Urinary incontinence, Ataxia (Weird, Wet, Wobbly) |
| Clinical signs of hydrocephalus | headache; nausea, vomiting; mental decline; papilledema ; altered gait |
| Subarachnoid Hemorrhage | Bright red: indicative of subarachnoid hemorrhage, Xanthochromic (yellow): if no jaundice, can also indicate subarachnoid hemorrhage |
| bacterial meningitis | elevated protein, decreased glucose, increased polymorphonuclear leukocytes |
| viral meningitis | slightly elevated protein, normal glucose, increased lymphocytes |
| Meningitis | inflammation of meninges (viral or bacterial infection) Triad of Symptoms: Fevre, Nuchal rigidity, Headache (Kernig’s sign, Brudinski’s sign) |
| How do the infective agents reach the meninges? | 1) bloodstream (most common pathway), 2) retrograde transport-Olfactory nerves, Peripheral nerves, 3) direct contiguous spread-Otitis media, Sinusitis |
| Encephalitis | inflammation of the brain parenchyma; viral, temporal lobes, caused by: herpes, rabies, arbovirus; symptoms, fever, headache, photophobia |
| Meningioma | Most common benign CNS tumor in adults, more common in women, Symptoms: Focal neurological signs, Headache, Seizures |
| Slowly Adapting Mechanoreceptors (SUPERFICIAL) | Merkel Disk Receptors = form discrimination pressure (small highly localized receptive field) |
| Slowly Adapting Mechanoreceptors (DEEP) | Ruffini Endings = stretch of skin (large receptive field & central zone of maximal sensitivity) |
| Rapidly Adapting Mechanoreceptors (SUPERFICIAL) | Meissner’s Corpuscles = medium fast |
| Rapidly Adapting Mechanoreceptors (DEEP) | Pacinian Corpuscles = very fast (larger continuous receptive field w/ central zone of max sensitivity) |
| Fine Discrimination of Sensation | Fingertips, Lips |
| Crude Discrimination of Sensation | Calf, Thigh, Back |
| 4 classes of somatosensory receptors | Mechanoreceptors, Proprioceptors, Nociceptors, Thermoreceptors |
| Mechanoreceptors | Respond to tactile stimulation, pressure, vibration |
| Types of Mechanoreceptors | Merkel, Ruffini, Meissner, Pacinian |
| Proprioceptors | (fast &myelinated & large diameter) signal changes in muscle length, tendon tension, joint angle |
| Types of Proprioceptors | Golgi tendon organs (respond to changes in tension: 1b fibers), Muscle spindles (respond to changes in length: 1a fibers), Joint receptors (respond to changes in angle of joint) |
| Thermoreceptors | Signal changes in temperature |
| Types of Thermorecptors | Activated by heat (35-45C), Activated by cold (17-35C) |
| Nociceptors | Signal changes that potentially can elicit tissue damage: also itch and tickle sensations |
| Types of Nociceptors | A delta mechanical nociceptors , C polymodal nociceptors (response to damaging temperatures) |
| Function of Proprioceptors | Conscious proprioception = conveyed via dorsal columns, Unconscious proprioception = conveyed via spinocerebellar tracts |
| Muscle Spindles | Muscle stretches intrafusal fibers stretch stimulates Ia afferent fibers stimulates α motor neurons extrafusal muscle fibers contractMuscle spindles are connected to 1a fibers |
| A delta mechanical nociceptors | sharp, pricking sensations (epicritic pain), rapidly conducted – (relative to C fibers but not relative to mechanoreceptor fibers) |
| C polymodal nociceptors | mechanical stimuli, chemical stimuli, temperature, slowly conducted, and dull, poorly localizeable pain associated with unmyelinated fibers and free nerve endings (unencapsulated) |
| Myelinated Fibers | A alpha (motor neurons - 1a, 1b), A beta (type II fibers), A delta (type III fibers) |
| Unmyelinated Fibers | C (type IV fibers) |
| Hypoxia (fiber susceptibility) | most susceptible to Type B |
| Pressure (fiber susceptibility) | most susceptible to Type A |
| Local Anasthetics (fiber susceptibility) | most susceptible to Type C |
| Dermatome | area of skin subserved by all afferent fibers of one dorsal root ganglia |
| Spinal Cord has 2 regional enlargements | Cervical enlargement & Lumbosacral enlargement (regions where large numbers of motor axons leave to innervate muscles of distal appendages and large numbers of sensory fibers enter spinal cord) |
| Cervical Enlargement | Associated w/ upper limb, Brachial Plexus |
| Lumbosacral Enlargement | Associated w/ lower limb, Lumbar/Sacral Plexus |
| Spinal cord is segmentally organized around 31 pairs of spinal nerves | 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, 1 coccygeal |
| Somatic afferent | -large diameter, heavily myelinated axons of neurons carrying information related to touch, position sense (proprioception), and vibration sense; -small diameter and poorly or unmyelinated axons carrying pain and temperature information |
| Visceral afferent | axons of visceral sensory neurons from various visceral organs |
| Ventral root contains two major axonal fiber types | -Somatic motor =Axons of alpha motoneurons, Axons of gamma motorneurons , -Visceral motor |
| Spinal Refelexes | -Stretch (deep tendon) reflex, -Withdrawal Reflex, -Crossed Extensor Reflex |
| Stretch (deep tendon) reflex | Primary mechanism for regulating muscle tone- Examples: triceps (C7 -8), biceps (C5-6) ankle (S1), knee jerk (L2-4) reflexes |
| Crossed Extensor Reflex | contralateral limb is extended to help support body |
| Tetanus toxin, anerobic bacteria clostridium tetani | inhibits the release of glycine from Renshaw cells , results in sustained contraction of axial and limb muscles producing muscle spasms |
| Locomotion | movement that is dependent on activity of multiple segments of the spinal cord – and |
| which can occur largely reflexively | |
| Dorsal ramus | superfical muscle and skin |
| Ventral ramus | deeper muscles |
| Herniated disk | Compress fibers in either dorsal root (most often) or ventral root, -common place= L4, L5 |
| Gray & White Matter in SPINAL CORD | White Matter= EXTERNAL: contains ascending and descending nerve fibers in tracts or fascicule, Gray Matter = INTERNAL |
| Dorsal Horn | derives from the alar plate -contains primarily sensory neurons and interneurons (receives sensory afferents from periphery & sends sensory efferents to brain stem, cerebral) |
| Ventral Horn | derives from the basal plate- contains primarily motor neurons (-Alpha motoneurons innervate extrafusal muscle fibers of skeletal muscle , -Gamma motoneurons innervate intrafusal muscle fibers of muscle spindles) |
| Proximal muscles | mapped out interior of ventral horn |
| Distal muscle | towards periphery of ventral horn |
| Flexors | Motor neurons that innervate flexors are deep in grey matter |
| Extensors | Motor neurons that innervate extensor are more superficial in grey matter |
| Polio | attacks LOWER motor neurons of Ventral Horn (Flaccid paralysis, Muscle atrophy, Muscle fasiculations , Arreflexia (loss of reflexes), Affects RETROGRADE transport |
| Nuclei of Clarke | send axons to the cerebellum via the inferior cerebellar peduncle = conveys information related to unconscious proprioception |
| 10 lamina layers- GREY MATTER) | 1 – 6 in dorsal horn,7 in Intermediate gray, 8 & 9in ventral horn, 10 around the central canal |
| 3 major spinal cord columns (funiculi)- WHITE MATTER | posterior white column (Posterior funiculus), lateral white column (Lateral funiculus) , anterior white column (Anterior funiculus) |
| Ascending tract in funiculi | relay sensory information from the spinal cord to the brain |
| Descending tracts in funiculi | carry motor information from the brain to the spinal cord |
| Posterior funiculus | -Sensory tracts |
| Lateral funiculus | -Motor and sensory tracts |
| Anterior funiculus | -Primarily motor tracts |
| spinal cord contains three major ascending sensory tracts | Spinothalmic tract (STT), Dorsal Column/Medial Meniscus Tract (DCML), Spinocerebellar Tract |
| Spinothalmic Tract (STT) | Pain & Temp, Crude Touch (poorly localizable) |
| Dorsal Column/Medial LeMeniscus Tract (DCML) | (Discriminative touch ,Conscious proprioception, Vibration sense) Somatosensory information = CUNEATE FASICULUS : Somatosensory info from UPPER body and limbs, GRACILE FASICULUS: Somatosensory info from LOWER body and limbs |
| Spinocerebellar Tract | Unconscious Proprioceptive Info (from muscle spindles and golgi tendon organs to the cerebellum) |
| DCML and STT tracts | pathway schematic- DCML(3 second order neurons cross at caudal medulla), STT(3 second order neurons cross in spinal cord) |
| Lateral Spinothalmic Tract (neospinothalamic tract) | Pain (Intensity & location)& Temp, Direct Pathway-Fast |
| Ventral Spinothalmic Tract (paleospinothalamic tract ) | Touch & Pressure (affective Component), Indirect Pathway |
| Romberg sign | patient starts to sway when closes eyes (loss of proprioceptive balance) |
| Lissauer’s tract | 1st order STT neuron located in DORSAL ROOT GANGLION, 2nd order STT neuron located in SUBSTANTIA GELATINOSA |
| Syringomyelia | which CSF enters spinal cord and causes a syrinx to form (syrinx: enlargement of central canal of spinal cord, especially cervical spinal cord – affects grey matter around central canal)- associated w/ arnold chiari malformation type 1 |
| 3 Spinocerebellar Tracts | Dorsal spinocerebellar tract, Ventral spinocerebellar tract, Cuneocerebellar tract (2 neurons each) |
| Ventral Spinocerebellar Tract | Located in ventrolateral region of lateral funiculus , Transmits GTO afferent information from DISTAL LOWER limbs to cerebellum..2nd order neuron in BASE OF DORSAL HORN…Projects to cerebellum through SUPERIOR cerebellar peduncle |
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