10 Flashcards
What are the 3 steps for sensory sensation?
- Physical stimulus
- Stimulus is transduced into nerve impulses
- Response
Receptor -> nerve impulses
What are the things that initiate this pathway?
- Ion channels
- Receptor potential
- Generator potential
- Stimulating the afferent neuron
What is modality?
They includes vision, hearing, touch, staste
What is intensity?
Strength of the stimulus
What happen during duration in sensory sensation
Adaptation occurs
What is localization in sensory sensation?
Two-point threshold
What is stimulus transduction?
The receptor transforms the stimulus energy into electrochemical energy = stimulus transduction
What is neural encoding?
Stimulus information is represented as a serious of action potentials (after stimulus transduction)
What is the general formula of ascending pathways in sensory tracts?
Receptor
-> 1st neuron
-> 2nd neuron
-> 3rd neuron
-> Cortex
Ascending pathways - Sensory tracts
-> What are the receptors that you can find?
- Exteroceptor (pain, temperature, touch)
- Proprioceptor (muscles, joints)
- Nociceptor
Ascending pathways - Sensory tracts
-> Where can you find the 1st neuron?
Spinal ganglion
Ascending pathways - Sensory tracts
-> Where can you find the 2nd neuron?
Posterior horn
Ascending pathways - Sensory tracts
-> Where can you find the 3rd neuron?
Subcortical structures
What are the 9 sensory tracts?
- Posterior/dorsal column (Gracile and cuneate tracts)
- Anterior spinothalamic tract
- Lateral spinothalamic tract
- Anterior spinocerebellar tract
- Posterior spinocerebellar tract
- Spinotectal tract
- Spino-olivary tract
- Spinoreticular tract
How many neuron can you find in 1 receptive field?
1 neuron
are the receptive fields overlapped?
Yes
What does the size of receptive fields depend on?
Location
Type of inhibition on receptive field
Lateral inhibition -> 2 point-segregation
What are the 4 subtypes of nociceptors?
Mechanical
Thermal
Mechano-thermal
Polymodal
What type of pain does mechanical nociceptors bring?
Sharp, pricking pain
What type of pain does thermal nociceptors bring?
Sharp/pricking pain
Slow, burning pain
What type of pain does mechano-thermal nociceptors bring?
Sharp/pricking pain
Slow, burning pain
What type of pain does polymodal nociceptors bring?
Slow, burning pain
3 places that you can find muscle and skeletal mechanoreceptors
- Muscle spindle
- Golgi tendon organ
- Limb proprioception
4 places with corresponding sensation that you can find cutaneous and subcutaneous mechanoreceptors
- Meissner’s corpuscule (flutter)
- Pacinian corpuscule (vibration)
- Ruffini corpuscule (steady skin indentation)
- Merkel receptor (steady skin indentation)
Where can you find somatosensory cortex (SI)?
Postcentral gyrus and in the depth of central sulcus
How many functional areas can you find within primary somatosensory cortex (SI)?
4
Where are afferent fibers coming from in primary somatosensory cortex (SI)? What is the information?
Ventral posterolateral nucleus (VPL)
-> Information is somatotopically organized, contralateral
Where are efferent fibers going to in primary somatosensory cortex (SI)? Where do they project in?
They’re going to secondary somatosensory cortex
-> They projects in the insula
Which layers of primary somatosensory cortex that have association connections?
Layers 2 and 3
Characteristics of association connections of primary somatosensory cortex (SI)
- Among the 4 areas
- Posterior parietal cortex
- SII
- Motor cortex
Which layers of primary somatosensory cortex (SI) that you can find callosal connections?
2 & 3
Which layers of primary somatosensory cortex (SI) that you can find subcortical connections?
Layers 5 & 6
Characteristics of subcortical connections
- Basal ganglia
- VPL
- Dorsal column nuclei
- Dorsal horn
Which piece of information that somatosensory system convey?
Information about stimuli that reach the skin, mucous membranes of position of body parts
What does the conscious part of somatosensory system correspond to?
The classical “tactile” sense
What are the 2 most important, anatomically and physiologically distinct parts?
- Epicritic sensibility
- Protopathic sensibility
Which system/tracts that involve in epicritic sensibility?
Dorsal column - medial lemniscal system
(epicritic sensibility the sensibility to gentle stimulations permitting fine discriminations of touch and temperature, localized in the skin.)
Which system/tracts that involve in protopathic sensibility?
(protopathic sensibility the sensibility to strong stimulations of pain and temperature)
Anterolateral system (spinothalamic tracts)
Which receptors (+ their corresponding places) involve in epicritic sensibility?
- touch - Meissner corpuscule
- vibration, strech – Paccinian corpuscule
- proprioception – muscle spindle, Golgi-tendon
organ
Which receptors (+ their corresponding places) involve in protopathic sensibility?
- mechanoreceptors
- thermoreceptors
- nociceptors
Pathway of medial lemniscal system
- neuron: spinal ganglion
- neuron: cunate and gracile nuclei
- neuron: thalamus
- neuron: SI
Pathway of medial lemniscal system
-> 1. neuron: spinal ganglion
-> Where can you find 1. neuron? (2)
cuneate and gracile fasicles
Pathway of medial lemniscal system
-> Where can you find 2. neuro within cuneate and gracile nuclei?
- Internal arcuate fibers
- Lemniscal decussation
- Medial lemniscus
Pathway of medial lemniscal system
-> Where can you find 3.neuron: thalamus
- Ventral posterior lateral nucleus (VPL)
- Thalamic radiation
Pathway of medial lemniscal system
-> Where can you find 4.neuron: SI?
- Postcentral gyrus
- Primary somatosensory cortex
Pathway of medial lemniscal system
-> Where can you find 4.neuron: SI?
- Postcentral gyrus
- Primary somatosensory cortex
What is the general pathway of spinothalamic tracts?
- neuron: spinal ganglion
- neuron: posterior horn neuron
- neuron: thalamus - ventral posterior lateral nucleus (VPL)
- neuron: SI
Spinothalamic tracts
-> What do you find in 2. neuron: posterior horn neuron? (3)
- White comissure
- VENTRAL spinothalamic tract - crude touch
- LATERAL spinothalamic tract - pain, temperature
Spinothalamic tracts
-> What do you find in 3.neuron: thalamus - ventral posterior lateral nucleus (VPL)
Thalamic radiation
Spinothalamic tracts
-> What do you find in 4.neuron: SI
- Post-central gyrus
- Primary somatosensory cortex
Spinothalamic tracts
-> Collaterals of nociceptive fibers reach the frontal lobe after synapsing in the ____
Thalamus (CM and MD nuclei)
What is the general pathway of dorsal trigeminal lemniscus (dorsal trigeminal thalamic tract)?
- neuron: trigeminal ganglion (Gasser’s) - mesencephalic nucleus of the trigeminal nerve
- neuron: principal sensory nucleus
- neuron: ventral posteromedial nucleus (VPM)
- neuron: SI
Dorsal trigeminal lemniscus (dorsal trigeminal thalamic tract)
-> What can you find in 1.neuron: trigeminal ganglion (Gasser’s) mesencephalic nucleus of the trigeminal nerve?
Sensory branches of the trigeminal nerve
Dorsal trigeminal lemniscus (dorsal trigeminal thalamic tract)
-> What can you find in 2.neuron: principal sensory nucleus?
- Decussating fibers
- Dorsal trigeminal lemniscus
Dorsal trigeminal lemniscus (dorsal trigeminal thalamic tract)
-> What can you find in 3.neuron: ventral posteromedial nucleus (VPM)?
Thalamic radiation
Dorsal trigeminal lemniscus (dorsal trigeminal thalamic tract)
-> What can you find in 4.neuron: SI?
- Post-central gyrus
- Primary somatosensory cortex
What is the general pathway of ventral trigeminal lemniscus (ventral trigeminothalamic tract)?
- neuron: trigeminal ganglion (Gasser’s)
- neuron: spinal trigeminal nucleus
- neuron: ventral posteromedial nucleus (VPM)
- neuron: SI
Ventral trigeminal lemniscus (ventral trigeminothalamic tract)
-> What can you find in 1.neuron: trigeminal ganglion (Gasser’s)?
Sensory branches of the trigeminal nerve
Ventral trigeminal lemniscus (ventral trigeminothalamic tract)
-> What can you find in 2.neuron: spinal trigeminal nucleus?
- Decussating fibers
- Ventral trigeminal lemniscus
Ventral trigeminal lemniscus (ventral trigeminothalamic tract)
-> What can you find in 3. neuron: ventral posteromedial nucleus (VPM)?
Thalamic radiation
Collaterals of nociceptive fibers reach the ___ lobe after synapsing in the thalamus (CM & MD nuclei)
frontal
Which tracts that provide epicritic and main proprioceptive information?
Spinocerebellar tracts
What are the 3 types of spinocerebellar tracts?
- Dorsal spinocerebellar tracts (of Flechsig) - uncrossed
- Ventral spinocerebellar tract (of Gowers)
- Cuneocerebellar tract - uncrossed
What is the role of dorsal spinocerebellar tract of (Flechsig) - uncrossed?
Providing proprioceptive and epicritic information from the lower half of the body
What is the general pathway of dorsal spinocerebellar tract of (Flechsig) - uncrossed?
- neuron: spinal ganglion
- neuron: Clarke-Stilling nucleus (T9-L3)
- neuron: spinocerebellum
What is the role of ventral spinocerebellar tract (of Gowers)?
Providing proprioceptive and epicritic information from the lower half of the body
What is the general pathway of ventral spinocerebellar tract (of Gowers)?
- neuron: spinal ganglion
- neuron: dorsal horn neurons (L4-S3)
- neuron: spinocerebellum
What is the role of cuneocerebellar tract - uncrossed?
Providing proprioceptive and epicritic information from the upper half of the body
What is the general pathway of cuneocerebellar tract - uncrossed?
- neuron: spinal ganglion
- neuron: accessory cuneate nucleus
- neuron: spinocerebellum
What is the role of nociceptors in viscerosensory system?
Adquate stimulus: mediate visceral pain
Is receptor density in viscerosensory system low or high?
Low
Are receptive fields in viscerosensory system small or large?
Large
What type of fibers can you find in viscerosensory system?
Viscerosensory/visceroafferent fibers
What type of nerves can you find in viscerosensory system?
Sympathetic and parasympathetic nerves
How can signals flow to parasympathetic and sympathetic nerves?
- physiologic receptors (innocuous input) → parasympathetic nerves
- nociceptors → sympathetic nerves
This is how signals flow to sympathetic and parasympathetic nerves
1. physiologic receptors (innocuous input) → parasympathetic nerves
2. nociceptors → sympathetic nerves
=> Is there any exceptions? Explain
exceptions: distal to the midpoint of the sigmoid colon; infraperitoneum
→ physiologic and nociceptive signals are conducted via parasympathetic pelvic nerves
Are fibers in viscerosensory system slowly or fast conducting fibers?
Slow conducting fibers
What are the 2 general pathways for sympathetic aferents? (nociceptive pathways)
- Thoracic region → cardiac and pulmonary nerves
- Abdominal region → splanchnic nerves
What are the pathways for parasympathetic afferents?
- Sacral parasympathetic afferents (S2-S4)
- Cranial parasympathetic afferents (S2-S4)
Cranial parasympathetic afferents (S2-S4)
-> 3 cranial nerves that have sensory ganglia?
CN VII, IX, X
Cranial parasympathetic afferents (S2-S4)
-> Which receptors relating to CN IX can you find?
- chemoreceptors of the carotid body
- baroreceptors of the carotid sinus wall
- nociceptors of the oropharynx
=> afferent of the gag reflex
Cranial parasympathetic afferents (S2-S4)
-> Which information can you find within CN X?
- physiologic information abour thoracic viscera
- physiological information about abdominal viscera
(Cannon-Boehm point!)
Cranial parasympathetic afferents (S2-S4)
-> In relation to CN IX &X, you can find physiological information about thoracic viscera and abdominal viscera (Cannon-Boehm point)
-> What is the pathway of this?
-> Inferior ganglia of CN IX and X
-> Solitary nucleus
-> Dorsal vagal nucleus (preganglionic parasympathetic neurons)
-> thoracic and abdominal viscera
Cranial parasympathetic afferents (S2-S4)
-> In relation to CN IX &X, you can find physiological information about cardiac ganglia and muscles of larynx, pharynx, oesophagus
-> What is the pathway of this?
-> Inferior ganglia of CN IX and X
-> Solitary nucleus
-> Nucleus ambiguus (parasympathetic visceromotor neurons)
-> cardiac ganglia and muscles of larynx, pharynx, oesophagus
Cranial parasympathetic afferents (S2-S4)
-> In relation to CN IX &X, you can find physiological information about cardiac ganglia and muscles of larynx, pharynx, oesophagus
-> How do you reach anterolateral medulla
-> Inferior ganglia of CN IX and X
-> Solitary nucleus
-> Anterolateral medulla
