9. Ascending sensory II Flashcards
(31 cards)
Most neurons of the grey matter are classified as…
Multipolar neurons
What are the neuron types of the grey matter
- Primary sensory
- Motor (alpha, gamma, visceral)
- Interneurons
- Projection neurons
What is the role of projection neurons
Relay signals to distant CNS areas; form a tract as they ascend
What is the role of interneurons
Local circuit neurons; relay sensory info to motorneuron, other interneuron or projection neuron
Where is the cell body of alpha (extrafusal)/gamma (intrafusal) motorneurons vs visceral motorneurons
- Alpha/gamma: ventral horn of C6-T2 and L4-S3
- Visceral: intermediate substance of T1-L3 (intermediolateral nucleus) and S2-S3 (parasympathetic nucleus)
Organization of SC grey matter
What are the 3 ‘horns’/ zone of the SC grey matter
- DORSAL (sensory)
- INTERMEDIATE ZONE (autonomic) - contains a lateral horn, which is a bulge formed by lamina VI
- VENTRAL HORN (motor)
Organization of SC grey matter
What are the two schemes of oraganization of the spinal cord
- Nuclear - based on groups of cell bodies
- Laminar - 10 laminae of Rexed based on cell structure
Organization of SC grey matter
Describe the localization of each laminae
Slide 22
- Lamina I-VI: dorsal horn
- Lamina VII + X: intermediate zone
- Lamina VIII: ventral horn
- Lamine IX: embedded in intermediate zone + ventral horn
Organization of SC grey matter
Name the SC grey matter nuclei
Dorsal horn
* Marginal nucleus
* Substantia gelatinosa
* Nucleus proprius
* Nucleus thoracicus
* Lateral cervical nuclus
Lateral horn/intermediate zone
* Intermediolateral nucleus
* Sacral parasympathetic nucleus
Ventral horn
* Medial & medial motor nuclei
Organization of SC grey matter
Marginal nucleus
- Lamina I
- Pain, touch, temp (exteroceptive)
- Entire SC
Organization of SC grey matter
Substantia gelatinosa
- Lamina II
- Interneurons (pain, touch, temp)
- Entire SC
Organization of SC grey matter
Nucleus proprius
- Lamina III-IV
- Interneurons + projection neurons
- Entire SC
Organization of SC grey matter
Nucleus thoracicus
- Lamina VI
- Proprioceptive info from PLs
- Unonscious - dorsal/ventral (PL) spinocerebellar tracts
- Conscious - spinomedullary tract (PL)
- T1-L4
Organization of SC grey matter
Lateral cervical nucleus
- Dorsolateral edge of dorsal horn
- Projection neurons
- Part of spinocervicothoracic tract (touch > pain)
- C1-C2
Organization of SC grey matter
Intermediolateral nucleus
- Lamina VII (intermediate zone)
- Sympathetic preganglionic neurons
- T1-L3
Organization of SC grey matter
Sacral parasympathetic nucleus
- Lamina VII (intermediate zone)
- Parasympathetic preganglionic neurons (to pelvic viscera)
- S2-3
Organization of SC grey matter
Know table slide 32!
okay okay
Unconscious ascending afferents
2 ascending pathways that do NOT reach conscious perception
Do not reach cerebral cortex directly
- Spinocerebellar tracts (muscle proprioception)
- Ascending reticular formation (all other senses)
Name the 5 spinocerebellar tracts
Pelvic limbs:
* Dorsal spinocerebellar tract
* Ventral spinocerebellar tract
Thoracic limbs:
* Spinocuneocerebellar tract
* Cranial spinocerebellar tract
Neck: (De lahunta)
* Cervicospinocerebellar tract
Spinocerebellar tracts
DORSAL spinocerebellar tract
- Muscle spindle
- DRG
- Nucleus thoracicus
- Ipsi dorsal spinocerebellar tract
- Caudal c.p
Spinocerebellar tracts
VENTRAL spinocerebellar tract
- GTO
- Base of dorsal horn
- Immediately decussates
- Contra ventral spinocerebellar tract
- Rostral c.p.
- Decussates again in the cerebellum
Spinocerebellar tracts
SpinoCUNEOcerebellar tract
- Muscle spindle
- Ascends ipsi cuneate fascicle
- LATERAL CUNEATE NUCLEUS (medulla)
- Caudal c.p.
Spinocerebellar tracts
CRANIAL spinocerebellar tract
- GTO
- Base of dorsal hon
- ipsi cranial sinocerebellar tract
- Either rostral or caudal c.p.
Which spinocerebellar tract is called the DIRECT pathway and why?
DORSAL spinocerebellar tract.
* No decussation
* Remains close to dorsal horn
* closest (caudal) c.p.
