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86 Cards in this Set
- Front
- Back
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Meissner's Corpuscle
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Stimulus: Flutter (5-40 Hz), Stroking
Location: Superficial layers of skin Structure: Encapsulated in connective tissue Rapidly Adapting |
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Merkel Cells
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Stimulus: Steady pressure, texture
Location: Superficial layers of skin Structure: Enlarged nerve endings Slowly Adapting |
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Ruffini Endings
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Stimulus: Stretch of skin
Location: Deep layers of skin Structure: Enlarged nerve endings Slowly Adapting |
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Pacinian Corpuscles
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Stimulus: Vibration (60-500Hz)
Location: Deep layers of skin Structure: Encapsulated in connective tissue Rapidly Adapting |
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Hair Follicle Endings
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Stimulus: Hair deflection
Location: Hair follicle endings Rapidly Adapting |
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Joint, Muscle, and Skin Receptors
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Submodality Subserved: Position sense and kinesthesia
Adequate Stimulus: Joint position and movement Rapidly Adapting and Slowly Adapting |
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Free Nerve Endings
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Stimulus: Various touch and pressure stimuli
Location: Around hair roots and under surface of skin Structure: Unmyelinated nerve endings Variable Adaptation |
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A-Alpha Nerve Fibers
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Muscle spindle primary ending
Golgi tendon organ |
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A-Beta Nerve Fibers
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Touch, pressure, vibration, flutter, hair, proprioception
Muscle spindle secondary ending |
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A-Delta Nerve Fibers
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Fast pain, cold, some touch (non-discriminative)
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C Nerve Fibers
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Slow pain, temperature, other receptors
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Spinal Cord - Dorsal Horn (Gray Matter)
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Sensory fibers from dorsal roots synapse with interneurons
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Spinal Cord - Ventral Horn (Gray Matter)
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Contain cell bodies of motor neurons that carry efferent signals to muscles and glands
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Spinal Cord - White Matter
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Ascending tracts: take sensory information to the brain
Descending tracts: mostly efferent (motor) signals from the brain to the cord |
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Dorsal Root
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Specialized to carry incoming sensory information
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Ventral Root
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Carries information from the central nervous system to muscles and glands
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Dorsal Column/Medial Lemniscal System
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Ascending tract for discriminative touch, vibration, and proprioception.
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Fasciculus Gracilis
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Most medial portion of the DCML, carries signals from the sacral and lumbar portions of the body
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Fasciculus Cuneatus
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Most lateral portion of the DCML, carries signals from the thoracic and cervical portions of the body
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Nucleus Gracilis and Nucleus Cuneatus
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Sites in the medulla that house the cell bodies of DCML 2nd order neurons. The axons of these 2nd order neurons decussate upon leaving the nuclei.
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Ventroposterior Lateral Nucleus
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Site within the thalamus where secondary efferents from the medial lemniscus synapse with 3rd order neurons that finally ascend to the cortex.
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Ventroposterior Medial Nucleus
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Site within the thalamus where axons from CN V synapse and from here ascend to the cortex.
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Medial Lemniscus
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Formed by axons of 2nd order neurons of the dorsal column pathway. Begins in the nucleus gracilis and nucleus cuneatus, decussates, and continues to the VPL of the thalamus.
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Topography of DCML
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Cord: foot medial, hand lateral
Thalamus: foot lateral; hand, face medial SI Cortex: foot medial; hand, face lateral |
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Lesions in DCML
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Increase 2 point threshold
Decrease vibratory sensitivity Decrease proprioception Increase in spontaneous pain |
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Submodalities of the Anterolateral Pathway
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Pain
Temperature Touch (less discriminative than DCML) Pressure Itch |
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Submodalities of Dorsal Column Pathway
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Fine touch
Vibration Proprioception |
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Somesthesia
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Ability to detect the quality, intensity, location, and timing of somatic stimuli
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Polymodal nociceptors
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Respond to mechanical, thermal, chemical energy; anything that causes tissue damage. Indicates that a common mechanism might exist, e.g. the release of a chemical from the damaged tissue that stimulates the receptors.
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Fast pain carried by _____ fibers.
Slow pain carried by _____ fibers. |
Alpha Delta
C |
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Receptors for the anterolateral system are all _____ nerve endings.
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free
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2nd order neuronal cell bodies for the anterolateral system are located in the _____.
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dorsal horn
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Axons of the anterolateral system decussate _____.
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in the spinal cord
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Spinothalamic tract (ALS)
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-Newest part
-Projects to VPL and SI, SII -Fast pain, Alpha-delta fibers |
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Spinoreticular tract (ALS)
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-To reticular formation & thalamus
-Contributes to arousal -C fibers |
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Spinomesencephalic tract (ALS)
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-To mesencephalic RF & PAG
-Contributes to affective component and pain control |
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Anterolateral system topographic representation
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Spinal Cord: Foot lateral, hand medial (contralateral)
VPL of Thalamus: Foot lateral, hand medial VPM of Thalamus: Face Reticular Formation and other target in thalamus: No organization SI/SII: Limited representation. |
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Gate Control Theory
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Collaterals of first order fibers of the Dorsal column system can indirectly inhibit pain transmission at its first synapse.
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Spinal Cord Transaction - Immediate Result
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Loss of all reflexes - areflexia
Flaccid paralysis Loss of autonomic function (urination, defecation) Lasts up to 3-4 weeks in humans |
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Spinal Cord Transaction - Longterm Result
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Slow return of reflex functions
Reflexes may strengthen over time - hyperreflexia Paralysis may become spastic Pathologic reflexes may appear (Babinski) |
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Muscle Spindle
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Stretch (length) receptor that sends information to the spinal cord and brain about muscle length and changes in muscle length. (Myotatic Reflex)
Located inside skeletal muscle |
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Golgi Tendon Organ
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Located at the junction of tendons and muscle fibers. Respond primarily to the tension (force) a muscle develops during contraction. (Inverse myotatic reflex)
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Ventral Gray Matter - Lateral
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Motor neurons of distal muscles of the segment
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Ventral Gray Matter - Medial
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Motor neurons of proximal muscles of the segment
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Ventral Gray Matter - Dorsal
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Motor nuerons of flexors
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Ventral Gray Matter - Ventral
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Motor neurons of extensors
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Medial Pathways
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Lateral Vestibulospinal Tract
Pontine Reticulospinal Tract Ventral Corticospinal Tract |
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Lateral Pathways
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Lateral Corticospinal Tract
Rubrospinal Tract |
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Reticulospinal Pathway
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From the reticular formation (RF - Pons), a medial motor system controlling posture and motor responses due to changes in equilibrium.
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Vestibulospinal Pathway
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From the vestibular nucleus (VN), a medial motor system controlling posture and motor responses due to changes in equilibrium.
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Rubrospinal Pathway
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From the red nucleus (RN - Midbrain), a lateral motor system affecting the motor neurons of distal muscles.
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Corticospinal Tract
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(Pyramidal Tract) Lateral system of axons projected from the cortex directly to alpha motor neurons of the cord concerned with skilled movement of distal muscles.
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Clinical signs of damage to Lateral Corticospinal System
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Weakness in distal flexors
Babinski sign No spasticity Loss of fractionation of movement PT Syndrome quite different |
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Clinical signs of damage to Medial Movement systems
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Decrease in proximal muscle tone
Impaired locomotion Manipulation of digits not impaired |
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Corticobulbar fibers
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Pyramidal tract axons sent to cranial nerve nuclei in the brainstem.
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Somatotopic Organization of Primary Motor Cortex
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Muscle map vs. Movement map
Foot medial; hand, face lateral |
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Contribution of cells in motor cortex to movement
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Movement onset
Force of movement Direction (population response) |
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Somatotopic organization of Premotor Cortex
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1. Controls GROUPS of muscles acting similarly @ a joint
2. 2 functional zones - rostral and caudal |
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Functions of Premotor Cortex
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1. Controls GROUPS of muscles acting synergistically
2. Develops activity before primary motor cortex; helps plan movement |
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Functions of Supplemental Motor Cortex
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Bilateral movement control
Programming for nonsymmetrical bilateral movements Mental rehearsal |
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Clonus
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Occurs when stretch receptors and Golgi tendon organs get stuck in a loop. The two mechanisms alternately trigger one another, causing the muscle to contract-relax-contract-relax. Sign of Pathology.
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Clasp-Knife Reflex
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It refers to a stretch reflex with a rapid decrease in resistance when attempting to flex a joint, usually during a neurological examination.
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Upper Motor Neuron Disease
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Weakness
Loss of abdominal reflexes Babinski sign Increased stretch reflexes Increased muscle tone Clonus Clasp-knife reflex |
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Lower Motor Neuron Disease
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Weakness and muscle atrophy
(no constant muscle tone to muscles due to interruption of spinal reflex arcs) |
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Purkinje Cells
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Output cells of Cerebellar cortex
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Mossy Fibers
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Input fiber to Granule Cells within the Cerebellum
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Climbing Fibers
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Input fiber to Purkinje cells within the Cerebellum
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3 Deep Nuclei of Cerebellum
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Dentate N., Interposed N., Fastigial N.
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Archicerebellum
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Controls midline proximal muscles via the medial motor systems
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Paleocerebellum
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Controls limbs, especially proximal limb muscles via medial motor systems and rubrospinal pathway
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Neocerebellum
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Controls distal skilled movements via lateral motor systems, especially the corticospinal tract
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Clinical manifestations of cerebellar damage
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1. Problems of: synergy, equilibrium, tone, intention tremor
2. Lesions produce disturbances ipsilaterally 3. Lesions in lateral portions produce distal problems whereas midline damage produces trunk incoordination. 4. No alterations in sensation. |
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Clinical manifestations of basal ganglia
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1. Change in muscle tone
2. Appearance of dyskinesias |
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Parkinson's Disease
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1. Due to loss of cells making dopamine in substantia nigra
2. Signs: Increased tone (rigidity, tremor at rest, bradykinesia) |
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Huntington's Chorea
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1. Due to loss of GABA neurons in Caudate and Putamen
2. Signs: Decreased tone, spontaneous 'flicking' movements in distal muscles, dementia |
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Athetosis
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1. Due to damge in motor cortex or Caudate and Putamen
2. Think oxygen debt @ birth 3. Signs: increased tone, spontaneous slow "wormlike" movements of limbs and head |
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Ballism (Hemiballismus)
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1. Due to damage to the subthalamic nucleus
2. Signs: Decreased tone, flailing movements of limbs. 3. Gets better over time. |
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Lateral Inhibition
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Process in which sensory neurons close to a stimulus are inhibited in order to intensify the perception of the stimulus. (2nd Order Neurons of DCML accomplish this)
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Fast Pain
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Short latency, well localized, subsides quickly
Has relatively minor affective component |
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Slow Pain
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Longer latency, less well localized, longer duration with prolonged "after-discharge"; has strong affective component; difficult to endure
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Substantia Gelatinosa
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The apical part of the posterior horn of the gray matter of the spinal cord
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Anterolateral Pathway - Neospinothalmic Portion of Contralateral Anerolateral Tract
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Projects to VPL of Thalamus, and from there to SI and SII.
FAST PAIN, Alpha Delta |
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Anterolateral Pathway - Older Portions of Contralateral Anerolateral Tract
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Project to other parts of Thalamus and/or the reticular formation.
C Fibers, High arousal properties. |
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Subdivisions of AL Pathway
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Spinothalmic Tract (Delta)
Spinoreticular Tract (C) Spinomesencephalic |
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Opiate Receptors
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In dorsal horn:
1. Terminals of primary afferents 2. Cell bodies of 2ndary afferents |
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Sites of Pain Transmission Blockage by PAG and Raphe Nuclei Projections
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1. Prevent primary afferent from passing on its signal by blocking neurotransmitter release
2. Inhibit 2ndary afferent so it does not send the signal up the spinothalamic tract. |
