Ascending & Descending Tracts

Ascending Tracts 

Anatomical principle

• Sensory modality: fine touch in one sensory neuron
• Somatotopic: ascending tracts arrange according to site of origin 
• Medial lateral rule: sensory neuron enter low level of spinal cord more medial 

First order: deliver sensation to CNS 
Second order: interneuron
Third order: transmit info from thalamus to cerebral cortex 

Descending Tracts 

Corticospinal tract 

• Corticobulbar: conscious control over eye, jaw, face muscle 
• Anterior & lateral corticospinal: skeletal 

Subconscious tract 

• Vestibulospinal
• send info from inner ear to monitor head position 
• respond by alter muscle tone, neck muscle contraction, limbs for posture & balance 
• Tectospinal 
• send info to head, neck, upper limb in response to bright, sudden movement and loud noise
• tectum area consist:
• superior colliculi: receive visual info
• inferior colliculi: auditory 
• Reticulospinal
• send info to cause eye movement 
• activate respiratory muscle 
• Rubrospinal 
• send info to flexor & extensor