Pathways

DCML pathway

Sensory stimulus → Primary sensory neuron → Dorsal Root Ganglion (1ST ORDER) → nucleus cuneatus for upper body or nucleus gracilis for lower body in medulla (2ND ORDER)(CROSSES OVER HERE) → Pons(secondary sensory neuron) → Midbrain(medial lemniscus) → VPL in thalamus (3RD ORDER) → posterior limb of internal capsule → S1

DCML functions

TVRD P

fine Touch

Vibration

touch Recognition

2 point Discrimination

conscious Proprioception

DCML order neurons ONLY

1st - DRG

2nd - Nucleus cuneatus/gracilis in medulla (below T6 is only gracilis)

3rd - Ventral Posterior Lateral (VPL) nucleus in the thalamus

Trigeminal Mechanosensory System

sensation for the face

Sensation → trigeminal nerve (CN5)/ ganglion (1ST ORDER) → trigeminal complex in the pons (2ND ORDER) → VPM of thalamus (THIRD ORDER) → S1/S2

Anterolateral system

ascending pathway for pain, temperature, coarse system

lateral path (fast pain) - spinothalamic tract

Medial path (slow pain) - spinomesencephalic, spinoreticular, spinolimbic

ALL CROSS AT LAMINA 1,2,5 (2ND ORDER)

Spinothalmic pathway

For fast pain

sharp/dull testing and temp testing

pain, temp, coarse tocuh stimulus → DRG (1ST ORDER) → primary sensory neuron→ Lamina 1,2,5 in spine (2ND ORDER) → up spine → rostral medulla → pons → midbrain → VPL (3RD ORDER) → S1/S2

Spinomesenchaplic

Orients eyes and head to pain

spine → midbrain

activates descending tracts for descending pain modulation

DRG (1ST ORDER) → lamina 1,2,5 (2ND ORDER) → pons → Periaqueductal grey and superior colliculus in midbrain (3RD ORDER)

Spinoreticular

arousal and attention to pain

spine → reticular formation → cortex

DRG (1ST ORDER) → Lamina 1,2,5 (2ND ORDER)→ reticular formation in brainstem(medulla then pons) (3RD ORDER) → mediodorsal and intralaminar thalamic nucleus → S1/S2

Spinolimbic

emotion and autonomic arousal associated with pain

spine → thalamus → Basal Ganglia, Amygdala, Hypothalamus, Limbic system, Anterior cingulate cortex, Insual

DRG (1ST ORDER) → Lamina 1,2,5 (2ND ORDER) → mediodorsal and intralaminar thalamic nuclei → BAHL AI

Pain/crude touch in the face

Trigeminal nerve/Ganglion (1ST ORDER) → Trigeminal complex in medulla (2ND ORDER) → descend to lower medulla then cross midline via trigeminal lemniscus → VPM in thalamus (3RD ORDER) → S1/S2

Spinocerebellar tracts

Unconscious proprioception info relayed to cerebellum

High fidelity (where the body actually is) → Dorsal SC and Cuneocerbellar

• input from joint, muscles, GTO

Internal (this is what’s happening, do better) → Ventral SC and Rostral SC

• communicate through decending interneurons to send an ascending message back to cerebellum

ALWAYS END IPSILATERAL

Dorsal SC

High fidelity

Legs and lower trunk

Leg/Lower trunk stimulus → DRG(1ST ORDER) → Clarke’s nucleus(2ND ORDER) → inferior cerebellar peduncle → Ipsilateral cerebellum

below L3/L4 there is no Clarke so it goes to fasciculus gracilise of the DCMLthen to Clarke

LICI/LIGCI

Cuneocerbellar

High fidelity

Arms and upper trunk

Arms/upper trunk → DRG (1ST ORDER) → fasciculus cuneatus → external cuneate nucleus in medulla (2ND ORDER) → inferior cerebellar peduncle → Ipsilateral cerebellum

Ventral SC

Internal (don’t have order neurons)

Legs

Interneurons → cross at anterior white commissure → cross back at superior cerebellar peduncle → ipsilateral cerebellum

Rostral SC

Internal (no order neurons)

arms but not much is known

interneurons → S/I cerebellar peduncle → cerebellum