Brainstem and Central Pathways

Brain Stem

Diencephalon

Thalamus

filter and select sensory information

Hypothalamus

site for integration of control of visceral organs

optic chiasm

site of crossing of optic nerves

pituitary gland

Midbrain (mesencephalon)

colliculi

involved in reflex eye movements

involved in reflex head movements

Pons

cerebellar peduncles

carry signals to and from the brainstem and cerebellum

Medulla oblongata

nucleus gracilis and cuneatus

termination sites of fasciculus gracilis and fasciculus cuneatus (general somatic senses)

medullary pyramid

ventrally located, contains pyramidal tracts

 

Spinal Somatosensory Pathways

Posterior Column Pathway

Fasciculus Gracilis and Cuneatus

from neurons sensing touch, pressure, vibration

project to Nucleus Gracilis and Cuneatus, then to Thalamus, and then to Primary Sensory Cortex

Spinothalamic Pathway

Lateral and Anterior Spinothalamic Tracts

from neurons sensing pain, temperature, touch and pressure

project to Thalmus, and then to Primary Sensory Cortex

 

Spinal Motor Pathways

Pyramidal Tracts

Anterior and Lateral Corticospinal Tracts

from neurons in the Primary Motor Cortex acting on skeletal muscle

project through medullary pyramids to Ventral Horns of spinal cord

 

David G. Ward, Ph.D.  Last modified by wardd 23 May, 2006