8. Ascending sensory I (senses + conscious proprioception) Flashcards
(37 cards)
What information relays the SOMATOSENSORY system
- Info from SKIN receptors (pain, touch, warmth, temp)
- Info from DEEPER structures such as muscles, tendons, joints, viscera (pressure, vibration, proprioception, deeper pain)
Sensory receptors
Sensory receptors are found in every tissues except…
Nervous tissues
Sensory receptors
2 means of classification of sensory receptors
- Type of NERVE endings (free vs encapsulated)
- STIMULI (mechano, chemo, thermo, noci, proprio)
Note; encapsulated are all mechanoreceptors
Sensory receptors
2 modes of adaptations of sensory receptors (slide 6)
- Phasic - rapidly adapting (stops firing for constant stimulus)
- Tonic - slow adapting (continues firing)
Sensory receptors
For each receptor, describe info conveyed and adaptation (table slide 14)
- HAIR FOLLICLE TERMINALS (free nerve endings): touch, fast
- MEISSNER’s CORPUSCLE: touch/vib, fast
- MERKEL’s CORPUSCLE: touch/press, slow
- RUFFINI’s CORPUSCLE: stretch, slow
- MUSCLE SPINDLE: prop, fast iniitial; slow sustained
- GTO: prop and muscle tension, slow
Difference between
* Dermatome
* Cutaneous zone
* Autonomous zone
* Receptor field
- DERMATOME: sensory zone represented by a single spinal nerve (nerve root) - overlap
- CUTANEOUS ZONE: sensory zone represented by a single peripheral nerve - overlap
- AUTONOMOUS ZONE: skin area detected by a single peripheral nerve with NO OVERLAP (applies to only few spinal nerves)
- RECEPTIVE FIELD: sensory zone represented by a single neuron.
What properties of a receptive field affects precision of localization (slide 21)
- Size of receptive field (larger = more overlap)
- Number of 1ary sensory neurons merging per 2nd-order neurons
Name the ascending/sensory tracts:
* General proprioception - conscious
- Fasciculus cuneatus
- Spinomedullary
Name the ascending/sensory tracts:
* General proprioceptiion - unconscious
- Dorsal spinocerebellar (PL)
- Ventral spinocerebellar (PL)
- Spinocuneocerebellar (TL)
- Cranial spinocerebellar (C1-T1)
- Cervicospinocerebellar (C1-C4, de lahunta)
Name the ascending/sensory tracts
* Pain, touch, temperature
- Spinothalamic
- Spinocervicothalamic
- Spinoreticular
Name the ascending/sensory tracts:
* Deep pain
- Spinothalamic tract (+ men)
- Ascending reticular formation (+ mammals)
Medial lemniscus - location, role
- Conveys afferents from the gracile-cuneate system + spinothalamic system (not reticular formation)
- Medulla –> thalamus
Pain
Difference between pain and nociception
- Pain: subjective response to stimulation of nociceptors (not tested)
- Nociception: behavioral response to noxious stimuli
Pain
Difference between neuropathic vs nociceptive pain
- Nociceptive: stimulation of nociceptors
- Neuropathic: stimulation of PNS or CNS
Difference between superficial vs deep pain in terms of
* Fibers
* Localization
* Tracts
SUPERFICIAL:
* Ad fibers, thinly myelinated, fast
* Accurately localized
* Spinothalamic
DEEP`
* C fibers, thinner, non-myelinated
* Poorly localized
* Ascending reticular +/- spinothalamic tract
Pain, touch, temp
Spinothalamic tract (slide 32)
- DRG (N1) -> dorsal horn (N2) -> decussates
- Dorsolateral fasciculus
- Medial lemniscus
- Thalamus (N3) -> internal capsule -> SI
Touch»_space; pain (5%)
Spinocervicothalamic tract (slide 32)
- DRG (N1) -> dorsal horn (N2)
- Ipsilateral spinocervicothalamic tract
- Lateral cervical nucleus (C1-2) –> decussates
- Medial lemniscus
- Thalamus (N4) -> internal capsule -> SI
Pain, touch, temperature
Spinoreticular tract
- DRG (N1) -> dorsal horn (N2)
- Bilateral ventral funiculi
- Various nuclei (N3) (olivary -> dentate; reticular formation)
Touch
Fasciculus gracilis & cuneatus (slide 35-6)
- DRG (N1, Aβ fibers) -> dorsal horn (N2)
- Dorsal funiculus, in gracile (PL, medial) + cuneatus (TL, lateral) fasciculus
- Gracile + medial cuneate nucleus (N3) -> decussates
- Medial lemniscus
- Thalamus -> internal capsule -> SI
Conscious proprioception - TLs (C1-T5)
Fasciculus cuneatus
- DRG C1-T5 (N1, Aα fibers) -> dorsal horn
- Dorsal funiculus, in cuneatus (TL, lateral) fasciculus
- Medial cuneate nucleus (N3) -> decussates
- Medial lemniscus
- Thalamus -> internal capsule -> SI
Conscious proprioception (PLs, caudal to T5)
Spinomedullary tract (slide 44)
N.b. nucleus Z is just next to nucleus gracilis
- DRG (N1, caudal to T5)
- Nucleus thoracicus (N2, T1-L4)
- Lateral funiculus, along dorsal spinocerebellar tract
- Nucleus Z (N3) rostral to nucleus gracilis -> decussates
- Thalamus -> internal capsule -> SI
Name the 6 sensory nuclei of the brainstem (slide 49)
- V-midbrain: Nucleus of the mesencephalic tract of trigeminal nerve (face proprioception)
- V-pons: Pontine sensory nucleus of the trigeminal nerve (face tactile sensation)
- V-medulla: Nucleus of the spinal tract of the trigeminal nerve (facial pain and temp)
- VIII-medulla: Cochlear + vestibular nuclei
- VIII-medulla: nucleus of solitary tract
Face proprioception
Mesencephalic tract of trigeminal nerve
- Mesencephalic nucleus (N1-exception, not DRG!) -> decussates
- Trigeminal lemniscus (quintothalamic tract)
- Thalamus (N2)-> SI or cerebellum
Where is the mesencephalic nucleus (nucleus of the mencephalic tract of V)? slide 51
Lateral edge of periaqueductal gray
