Ascending Tracts of goll and burdach (fasciculus gracilis and fasciculus cutnaeous )

They are also called fasciculus gracilis and fasciculus cunateous

SENSATIONS

• fine touch

• propioception

• vibration

• pressure

PATHWAY

• First-order neuron -

  • arises from receptors

  • enters spinal cord through posterior root

  • cell body resides in dorsal root ganglia

  • it ascends on the same side to end in the nucleus gracilis and nucleus cutaneous present in the medulla

  • fibers closer to the midline are from the lower parts of the body

  • the lateral fibers are from the upper part of the body

• Second-order neuron

  • arises from the nucleus gracilis and nucleus cutaneous

  • they cross to the opposite side

  • ends in the ventral posterolateral nucleus of the thalamus

• Third-order neuron

  • arises from the thalamic nucleus

  • ends in the sensory cortex (areas 3, 1 and 2)
    

RELAY

they have two relays

• medulla

• thalamus

IN SHORT

1. receptor

2. dorsal root ganglia

3. ascending fibres

4. fasciculus gracilis and fasciculus cutaneous

5. ventral posterolateral nucleus o thalamus

6. cerebral cortex

FUNCTIONS

i. Fine (epicritic) tactile sensation ii. Tactile localization iii. two-point discrimination iv. Conscious kinesthetic sensation v. Stereognosis It is also a synthetic sense produced by a combination of touch and pressure sensations.

EFFECT OF LESION

• Loss of fine tactile sensation; however, crude touch sensation is normal

• Loss of tactile localization

• Loss of two point discrimination

• Loss of sensation of vibration

• Astereognosis (inability to recognize known objects by touch while closing the eyes)

• Lack of ability to differentiate the weight of different objects

• Loss of proprioception (inability to appreciate the position and movement of different parts of the body)

• Sensory ataxia or posterior column ataxia