Ascending and descending tracts Flashcards
Ascending tracts: Posterior white column consist of
- Fasciculus GRACILIS
- Fasciculus CUNEATUS
Ascending tracts: Lateral white column
- Lateral spinothalamic
- Posterior spinocerebellar
- Anterior spinocerebellar
- Spino-olivary
- Spinotectal
Ascending tracts: Anterior white column
- Anterior spinothalamic
- Tectospinal
Descending tracts : Lateral white column
- Lateral corticospinal tract
- Rubrospinal tract
Descending tracts: Anterior white column
- Anterior corticospinal tract
- Tectospinal tract
- Vestibulospinal tract
- Olivospinal tract
Descending tracts: Other descending tracts
- Reticulospinal tracts –lateral and medial
- Descending autonomic fibres
Function Anterior spinothalamic tract:
Touch and Pressure
Function Lateral Spinothalamic tract:
Pain and Temperature from the opposite half of the body
Function:
Anterior & posterior Spinocerebellar tract
Unconscious muscle joint sense from the trunk and lower limb.
Function:
Fasciculus gracilis
* Fasciculus cuneatus
Discriminative touch, vibratory sense, Conscious Proprioception (muscle joint sense)
Function Spino-tectal tract:
Slow Pain, thermal & tactile information to the superior colliculus of mid brain; Helps in the spino- visual reflexes
Function Spino- reticular tract:
Carrying the information of muscles, joints & skin to the reticular formation & also the slow pain
Function Spino-olivary tract:
Indirect pathway to cerebellum
Function of Sensory cortex of cerebrum:
localizes, discriminates and analyses different modalities of exteroceptive and proprioceptive sensations
F. CUNEATUS (TRACT OF BURDACH)::
Present lateral to the fasciculus gracilis in the upper part of the cord up to the mid-thoracic level (T6)
Carries ipsilateral fibers from the upper limb & part of the trunk above the mid-thoracic level.
F. GRACILIS (TRACT OF GALL)::
Present throughout the length of the spinal cord.
->Carries ipsilateral fibers from the lower limb & part of the body below the mid-thoracic level.
Function: Fasciculus gracilis & Fasciculus cuneatus :
Discriminative touch, vibratory sense, Conscious Proprioception (muscle joint sense)
Damage to Fasciculus gracilis & Fasciculus cuneatus results in what ?
Tabes dorsalis-Involvement of posterior white column and dorsal root in syphilitic degenerative disease
Romberg’s sign- patient is not able to tell the position or movements of his lower limbs unless he sees them.
Receptors involved in Fasciculus gracilis & Fasciculus cuneatus -
- Meissner’s corpuscle – tactile receptors
- Golgi-Mazzoni corpuscle – senses vibratory pressure and touch
- Pacinian corpuscle – senses vibration and pressure
Function of Lateral Spinothalamic tract:
Pain & Temperature from the opposite half of the body
Function of Anterior spinothalamic tract:
Light touch and pressure from the contralateral side of the body
Order neurons for Lateral spinothalamic tract:
- 1st order neuron: posterior root ganglion
- 2nd order neuron: substantia gelatinosa
- 3rd order neuron: ventral posteriolateral nucleus of the thalamus
Order neurons for Anterior spinothalamic tract:
- 1st order neuron: posterior root ganglion
- 2nd order neuron: substantia gelatinosa
- 3rd order neuron: ventral posteriolateral nucleus of the thalamus
Lateral spinothalamic tract become superficial in what region ?
the cervical region
-> cordotomy can be performed safely at this level to relieve the pain in the opposite half of the body
Function of Posterior spinocerebellar tract:
- Begins at the level of the T1 to L2 segment from the axons of the Clark’s column (posterior spinocerebellar)
- Unconscious muscle joint sense from the trunk and lower limb
Function of Anterior spinocerebellar:
Begins at the level of the L2 or L3 segment from the axons of the spinal border cells (anterior spinocerebellar ).
This tract carries unconscious muscle joint sense from the trunk and lower limb, fibres of this tract arise in the thoracic and lumbar levels
spinocerebellar tracts carry what information?
unconscious proprioceptive information
->help our brain co-ordinate and refine motor movements.
Posterior spinocerebellar tract carry what information?
Carries proprioceptive information from the lower limbs to the ipsilateral cerebellum.
Cuneocerebellar tract carry what information?
Carries proprioceptive information from the upper limbs to the ipsilateral cerebellum.
Anterior spinocerebellar tract carry what information?
Carries proprioceptive information from the lower limbs. The fibres decussate twice – and so terminate in the ipsilateral cerebellum.
Rostral spinocerebellar tract carry what information?
Carries proprioceptive information from the upper limbs to the ipsilateral cerebellum.
