Topic 1 Somatosensory cortex and somatosensory pathways Flashcards
List the different modalities of somatic sensation and the receptors associated with them
Spinothalamic
Pain(free nerve endings)
Temp( free nerve endings)
Light touch( Merkles disks)
Dorsal column system
Descriminative touch (Meissners corpuscle)
Pressure( Ruffini’s endings & pacinian corpuscle)
Vibration( Pacinian corpuscle)
Conscious proprioception (golgi tendon organ & muscle spindle)
Spinocerebellar
Unconcious proprioception & cutaneous information for coordination of movement
what is the role of the following receptors Pacinian corpuscle Meissners corpuscle Ruffini endings Merkle disks Free nerve endings
Pacinian corpuscle- Vibration & pressure
Meissners corpuscle- Fine/descriminative touch
Ruffini endings- Pressure
Merkle disks- Light touch
Free nerve endings- Pain, temp, itch,touch
List the ascending tracts of SC
sensory
Spinothalamic tract
(Pain temp light touch)
Dorsal column system
( Descriminative touch, vibration , proprioception)
Spinalcerebellar tract
( Unconious proprioception & cutaneous information for coordination of movement)
Spinothalamic tract
Spinothalamic tract
(Pain temp light touch)
CROSSED ( crosses immediately after entering SC)
1st order neuron cell body
DORSAL ROOT GANGLION
2nd order neuron cell body
DORSAL HORN OF SC
>projects to contralat spinothalamic tract and ascends
3rd order neuron cell body
VENTRAL POSTERIOR Nucleus of THALAMUS
>synapses with primary somatosensory cortex
Dorsal column system
Dorsal column system/ medial lemniscal
( Descriminative touch, vibration , proprioception)
UNCROSSED TRACT
Doesnt cross at level it enters , crosses at MEDULLA
1st order neuron cell body
DORSAL ROOT GANGLION
>ascends through ipsilateral dorsal funiculus( fasiculus gracilis/cuneatus)
2nd order neuron cell body
NUCLEUS GRACILLIS/CUNEATUS of medulla
>crosses via internal arcuate fibres of medulla
>ascends as medial lemniscus
3rd order neuron cell body
VENTRAL POSTERIOR NUCLEUS OF THALAMUS
>synapses with primary somatosensory cortex
- there is no fasiculus cuneatus for lumbar or sacral regions
Spinocerebellar tract
Spinalcerebellar tract
( Unconious proprioception & cutaneous information for coordination of movement)
Ventral= CROSSED
Dorsal =UNCROSSED
Sensory homunculus
Like someone lying on brain with feet in the corpus callosum
Primary somatosensory area
Brodmans areas: 3,1,2
What are the numbers for brodmans areas
Somatosensory association area
Brodmans: 5, 7
Brodmans numbers for Primary visual area
& visual association area
PRIMARY: Brodman’s 17
ASSOCATION: Brodman’s 18,19
Brodmans number for:
Primary Auditory area
Auditory assocation area
Wernikes area
PRIMARY:Brodmans 41
ASSOCATION: Brodmans 42
Auditory association area Wernikes area: 22
