Changes

*Ascending tracts cross over the midline of the body to the contralateral side of the [[Forebrain - Anatomy & Physiology#Thalamus|thalamus]].

*Ascending tracts cross over the midline of the body to the contralateral side of the [[Forebrain - Anatomy & Physiology#Thalamus|thalamus]].

*The [[Forebrain - Anatomy & Physiology#Thalamus|thalamus]] directs the signal to the [[Forebrain - Anatomy & Physiology#Cerebral Cortex|cerebral cortex]] for conscious perception.

*The [[Forebrain - Anatomy & Physiology#Thalamus|thalamus]] directs the signal to the [[Forebrain - Anatomy & Physiology#Cerebral Cortex|cerebral cortex]] for conscious perception.

**The pathway is direct, with very few [[Nervous System - PNS - Anatomy & Physiology#Nerve Fibre|neurones]] involved.

**The pathway is direct, with very few [[PNS Structure - Anatomy & Physiology#Nerve Fibre|neurones]] involved.

====1. Dorsal Columns====

====1. Dorsal Columns====

*True pain sensation; pain lasts longer.

*True pain sensation; pain lasts longer.

*Sensory information enters the [[Spinal Column - Anatomy & Physiology|spinal cord]] on the ipsilateral side of the stimulus. Some signals cross to the contralateral side of the body.

*Sensory information enters the [[Spinal Column - Anatomy & Physiology|spinal cord]] on the ipsilateral side of the stimulus. Some signals cross to the contralateral side of the body.

*The tract consists of '''several''' [[Nervous System - PNS - Anatomy & Physiology#Nerve Fibre|short neurones]].

*The tract consists of '''several''' [[PNS Structure - Anatomy & Physiology#Nerve Fibre|short neurones]].

*Therfore the ascending reticular formation is ''bilateral'' and ''multineuronal''.

*Therfore the ascending reticular formation is ''bilateral'' and ''multineuronal''.

*This pain pathway is more primitive than the [[Sensory Pathways - Anatomy & Physiology#Spinothalamic Tract|spinothalmic tract]].

*This pain pathway is more primitive than the [[Sensory Pathways - Anatomy & Physiology#Spinothalamic Tract|spinothalmic tract]].

'''Spinothalamic Tract'''

'''Spinothalamic Tract'''

*Fast, initial pinprick is detected by free [[Nervous System - PNS - Anatomy & Physiology#Nerve Fibres|nerve]] endings

*Fast, initial pinprick is detected by free [[PNS Structure - Anatomy & Physiology#Nerve Fibres|nerve]] endings

*Causes an impulse along large, myelinated fibres

*Causes an impulse along large, myelinated fibres

*Pain sensation is localised, and ends quickly

*Pain sensation is localised, and ends quickly

'''Ascending Reticular Formation'''

'''Ascending Reticular Formation'''

*A painful sensation is detected by free [[Nervous System - PNS - Anatomy & Physiology#Nerve Fibres|nerve]] endings

*A painful sensation is detected by free [[PNS Structure - Anatomy & Physiology#Nerve Fibres|nerve]] endings

*Causes an impulse along small, unmyelinated fibres

*Causes an impulse along small, unmyelinated fibres

*A delayed sensation of pain is percieved, that is less localised, persistent.

*A delayed sensation of pain is percieved, that is less localised, persistent.