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Somatosensory Pathways - Coggle Diagram
Somatosensory Pathways
Afferent Sensory info to cortex
Senses
General Senses
Proprioception
Pain
Touch
Temperature
Special Senses
Taste
Smell
Hearing/Balance
Vision
Types of Fibres
Type II
Large Myelinated
Type A-alpha or A-beta
Fine touch
Proprioception
Type III
Small Myelinated
Type A-delta
Gross touch
Cold
Sharp pain
Type Ia Ib
Large Myelinated
Golgi Tendon Organ & Muscle Spindles
Reflex arcs
Type IV
Non-myelinated
Type C
Hot temperatures
Burning
Pathways
Spinothalamic (Anterolateral pathway)
sharp pain & cold temps
Myelinated A-delta fibres
Hot temps, crude touch, burning pain, pressure
un-myelinated C-fibres
1st Order neuron enters through Dorsal Root
Travels up 2 vertebral segments prior to 2nd order synapse (posterior horn of spinal cord)
Lateral & anterior tracts travel up spinal cord to reach thalamus (3rd order synapse)
3rd Order synapse w/ 4th order in sensory cortex
Decussate through central canal to anterior part of spinal cord
Lateral tract = pain, pressure & temp info
Anterior tract = crude touch info
Dorsal Column Medial Lemniscus (Posterior Pathway)
Fine Touch and Proprioception
Large Myelinated (A-alpha & A-beta, and Type 1a,1b)
Through Posterior (Dorsal) Funiculus
Cuneate fasicle (lateral) = Arms & Chest info
Gracilis Fascicle (medial) = Trunk & Leg info
Travels to Medulla (1st order synapse w/ 2nd order)
Cuneate Nuclei of Medulla
Gracilis Nuclei of Medulla
Fibres Decussate here at the medial lemniscus of medulla
2nd order pass through pons and mid brain to Thalamus
2nd Order & 3rd Order synapse at Thalamus (Ventralposterolateral thalamus)
3rd Order synapse w/ 4th Order in sensory cortex
Some 1st order neurons synapse w/ interneurons
Reflex arcs through posterior horn of spinal cord
Spinocerbellar tracts
Proprioceptive info from Golgi Tendon (GTO) and Muscle spindles (MS)
Dorsal Spinocerbellar.= GTO & MS lwr limb
Cuneocerebellar = GTO & MS upper limb
Ventral spinocerebellar =GTO only lower limb
Rostral spinocerebellar = GTO only upper limb
1st order through DRG
Neuron Relay
1st Order: Sensory receptors converted to stimuli
2nd Order: Cell body in spinal cord or brainstem
3rd Order: Cell body in Thalamus
4th Order: Cell body in sensory cortex