NEURO sens pathways

robbypowell's version from 2015-07-20 13:18


Question Answer
what are the 4 types of general somatic sensation?Pain, Touch, Temperature, Position
what are the 5 types of “special” sensation?Olfaction (smell), Vision, Gustation (taste), Equilibrium (balance), and Hearing
What type of sensory receptors receive external stimuli & are near surface of body?Exteroceptors
What type of sensory receptors monitor internal environment and we are commonly not consciously aware of their input?Interoceptors
What type of sensory receptors sense body position and movement?Proprioceptors
What type of receptors detect touch, vibration, hearing, proprioception, equilibrium and blood pressure?Mechanoreceptors
What type of receptors have a FREE NERVE ENDING and detect damage to tissues (pain)?Nociceptors
What type of nociceptive fibers are myelinated and give acute, sharp, and fast pain?A-delta fibers
What type of nociceptive fibers are unmyelinated and give chronic, aching, and slow pain?C-fibers
What type of receptors are the same as pain receptors and detect temperature?Thermoreceptors
What type of receptors detect light?Photoreceptors
What type of receptors detect molecules (taste and smell) ?Chemoreceptors
What type of visceral receptors detect chemicals in the blood and osmolarity?Chemoreceptors
What type of visceral receptors detect blood pressure?Baroreceptors
In the skin, what type of receptors (specific name) sense deep pressure, vibration & proprioception? What layer are they found in?Pacinian Corpuscle; Dermis (deeper layer)
In the skin, what type of receptors (specific name) sense continuous touch and pressure, stretch, and are mainly present in the fingers? What layer are they found in?Ruffini Organ, Dermis f fingers (deep layer)
In the skin, what type of receptors (specific name) send light touch and are found in the finger tips? What layer are they found in?Merkel’s disc; Epidermis (superficial layer)
In the skin, what type of receptors (specific name) sense pain, temperature and touch and what layer are they found in?free nerve endings
In the skin, what type of receptors (specific name) sense two-point discrimination? What layer of the skin are they found in?Meissner’s corpuscle; Epidermis
What type of sensation do Meissner’s corupuscles sense?two-point discrimination
What type of sensation do Merkel’s discs sense?Light touch
What types of sensation do Ruffini organs sense?Continuous touch, pressure, and stretch
What types of sensation do Pacinian corpuscles sense?Deep pressure, vibration and proprioception
What two types of skin sensory receptors are found in the dermal layer and below?Ruffini organs and Pacinian Corpuscles
What 3 types of skin sensory receptors are found in the epidermis?Meissner’s corpuscles, Merkel’s discs & free nerve endings
What are the simplest sensory receptors?Thermoreceptors/Nociceptors (free nerve endings)
What are the 4 aspects of sensory input that are coded by the nervous system?(MILD) Modality (type), Intensity (how much stimulus), Location (where), Duration (tonic vs phasic receptors)(adapting vs. non-adapting)
How does a non-adapting (tonic) receptor work?maintains sensation as long as stimulus is applied (e.g. proprioceptors)
How does an adapting (phasic) receptor work?stops firing when stimuli are constant (e.g. smell)
What is mnemonic for asking patients about characters or aspects of pain?OLDCART (Onset, Location, Duration, Character, Alleviating factors, R, Timing)
Lowest possible sensory input for sensationSensory Threshold
Most active cells inhibit their neighbors in order to make the sensory input more sharp and clear… this mechanism of sensory processing is called ____ ____Lateral Inhibition
When a single receptor axon receives synapses from many postsynaptic cells in order to amplify the effect of a single receptor this is referred to as _______DIVERGENCE (one into many)
When many receptor axons synapse to a single postsynaptic cell in order to increase signal over noise this is referred to as _____CONVERGENCE
is two point discrimination more powerful on finger tips or back?finger tips
T/F: The LARGER a receptive field, the MORE DIFFICULT to localize a stimulusTrue (e.g. itch)
Paresthesia (tingling or numbness in some part of body) can almost always be attributed to …Pressure on a nerve
which order of sensory fiber crosses over from left to right?2nd Order sensory fibers cross over (in CNS)
The area of skin that provides sensory input to each vertebral segment is called a _____dermatome
What are the 2 spinal posterior funiculi and what types of sensory information do they carry?Gracile & Cuneatus; Light Touch (special discriminating touch) & conscious Proprioception
What spinal funiculi (posterior, lateral, or anterior) carry Light Touch and conscious proprioception?Posterior (Gracile & Cuneatus)
What spinal funiculi (posterior, anterolateral, or spinocerebellar) carry unconscious Proprioception?Spinocerebellar (lateral) Funiculi (P. & A. Spinocerebellar tracts)


Question Answer
The tendency for most ascending spinal nerves to stack toward midline (with most inferior body at midline and most recent or superior nerves joining toward lateral) is called ____SOMATOTOPY
What two tracts make up the Spinocerebellar pathway?Anterior and Posterior Spinocerebellar tracts
What two tracts make up the Anterolateral pathway?Anterior and Lateral Spinothalamic tracts
What are the three orders of neurons for the Posterior column pathway and what types of sensation does it carry?1st order DRG to spinal cord, 2nd order gracilis or cuneatus nuclei —> VPL thalamus crosses midline in its path, 3rd order VPL thalamus communicates with cortext; carries FINE touch (discriminating touch, vibration, proprioception HIGHLY LOCALIZED)
Gracile and Cuneate tracts are separated at what level of spinal cord nerves?T6
What are the receptors of the posterior funiculi?Muscle and Tendon spindles, Meissner’s Corpuscles, & Pacinian Corpuscles
What is another name for the Posterior Column Pathway?Medial Lemniscal Pathway (gracile & cuneate) (fine touch, vibration, proprioception)
At what order do fibers in the Posterior Column Pathway (Medial Lemniscal Pathway) cross to the contralateral side?2nd Order (from Cuneate or Gracile nuclei to contralateral VPL thalamus)
What is a Positive Romberg sign and what does it indicate?Loss of balance when eyes are closed; Lesion in Gracile & Cuneate tracts
What does loss of Kinesthesia (conscious proprioception) on the right side indicate?Lesion on Ipsilateral Gracile and Cuneate tracts
What tract carries CRUDE touch and pressure sensations (back-up system of touch)? What pathway is it part of?Anterior Spinothalamic tract; Anterolateral Pathway
What tract carries pain and temperature sensations? What pathway is it part of?Lateral Spinothalamic tract; Anterolateral Pathway
At what order do Spinothalamic fibers of the Anterolateral Pathway cross over the midline?2nd order (enter spinal cord and go up 2-3 segments, synapse, then cross over and ascend to thalamus)
What are the receptors of the Lateral (ventral) Spinothalamic tract?Free Nerve endings (pain and temperature)
Afferent fiber types associated with Lateral Spinothalamic tract?A-Delta (myelinated) fibers (acute, sharp pain) and C-fibers (unmyelinated, dull, chronic pain)
Where do 1st order neurons of Lateral Spinothalamic tract terminate?Lamina 1-4 (1 = posteromarginal nucleus, 2 = substantial gelatinosa, 3 + 4 = nucleus propreus)
Where do the 2nd order neurons of the Lateral Spinothalamic tract terminate?VPLN Thalamus
Where do the 3rd order neurons of the lateral Spinothalamic tract terminate?upper 2/3 of sensory area in post central gyrus (Bradman’s Area 3)
What would be the symptoms of a lesion in the Lateral Spinothalamic tract?Loss of Pain & Temp sensation on opposite side of lesion (2 segments below level of lesion) (e.g. lesion on left side at T8 causes loss of sensation on the right side below T10)
A lesion of the left Lateral Spinothalamic tract at T8 would cause loss of ___ & ___ sensation on the ___ side below the level of ____Pain & Temp; Right; T10
Central Pain is caused by a lesion to one of what two areas?Spinothalamic tract, Thalamus
Thalamic Syndrome can result in what 3 symptoms?Spontaneous pain, Contralateral Hemianesthesia, & Contralateral Hemiparesis
Cerebellum receives ___ & ___ information about the position of skeletal muscles, tendons, & jointsProprioceptive & Touch
What are the 2 Cerebellar tracts (unconscious proprioception)?Cuneocerebellar & Dorsal Spinocerebellar
Where does the information traveling via the Dorsal Spinocerebellar tract come from and what type of info is it?from Trunk & Lower Limbs (C8-L2)
What is the 2nd order Nucleus of the Dorsal Spinocerebellar tract?Nucleus Dorsalis (of Clarke) or Clarke’s Nucleus
What tract is Clarke’s Nucleus associated with and what order is it in the pathway?Dorsal Spinocerebellar tract; 2nd order
What are the 3 tracts of the Spinocerebellar pathway? Which of the 3 DOES cross the midline?Dorsal Spinocerebellar (LL & Trunk C8-L2), Cuneocerebellar tract (upper limb C2-C7), and Ventral Spinocerebellar (L2-S2) Crosses midline twice
What type of lesion is associated with Ataxia and/or alcoholism?Cerebellar (Ataxia)
What is the accepted explanation of referred pain?Visceral pain (e.g. heart) don’t have conscious sensory pathways, but interneurons transfer their pain activity to other conscious areas. (e.g. skin of right shoulder)
5 listed types of InteroceptorsNociceptors, Thermoceptors, Tactile receptors, Baroreceptors, Chemoreceptors
What are the 4 nuclei of trigeminal nerve and which are sensory which are motor?Mesencephalic (sensory) Primary Tirgeminal nucleus (sensory) Spinal nucleus of Trigeminal (sensory) Motor Trigeminal nucleus (motor)
Where are the 1st order nuclei of the Trigeminal sensory pathway?Trigeminal Ganglia (pseudo unipolar)
symptoms of lesion of trigeminal LemniscusContralateral loss of pain, temperature, proprioception (note that touch is not severely affected b/c it is bilaterally represented)
What are the 3 trigeminal reflexes?Corneal Reflex (blinking), Lacrimal Reflex, Masseteric Reflex (jaw jerk)
Sensory limb of Lacrimal Reflex (tearing up)Olfactory n —> Trigeminal nucleus
Secretomotor limb of Lacrimal ReflexFacial nerve (intermedius)
Corneal refelx sensory limbophthalmic n
Corneal reflex motor lumbfacial nerve
Masseter reflex afferentV3 sensory root
Masseter reflex efferentV3 motor fibers
Trigeminal neuralgia most frequently affects (gender) older than (age)Women, 50+
3 medicines used to treat Trigeminal NeuralgiaCarbamazepine, Phenytoin, Baclofen
What do Substantia Gelatinoso of Rondo do that can modulate pain sensation?release ENKEPHALINS which inhibit release of substance P (by pain fibers)
Irritation of the Dorsal Root Ganglion is referred to as _____ painRADICULAR
Where does pain of appendicitis refer to?around Umbilicus (belly button)
Where does the pain of Cholecystitis (gallbladder) refer to?tip of right shoulder
Epidurals and Opioids act on ____ pathways of pain sensationDescending
Loss of pain & temperature on one side of the body and loss of tactile, vibratory and position sense on the other side caused by ____ ____ syndromeBrown Sequard syndrome
Bilateral impairment of pain and temperature over arms and shoulders indicative of damage to ____ ____ ____ at lower cervical and upper thoracic levelsAnterior White Commissure
Enlargement of central canal of spinal cord (damaging spinal cord crossing fibers)Syringomelia
Most common cause of Stocking and Glove pattern of sensory loss (indicate peripheral neuropathy)Diabetes Mellitus

abnormal sensations

Question Answer
ParesthesiaSpontaneous sensation of prickling, tingling or numbness
HyperalgesiaExaggeration of tactile sensation stimuli
HypoalgesiaDiminished sensitivity to stimuli
Analgesiacomplete loss of pain
AnesthesiaComplete loss of consciousness