MAJOR ASCENDING TRACTS OF TIlE SPINAL CORD

Fasciculus gracilis: contains fibers from sacral, lumbar, and the lower six thoracic segments. These axons are located in the medial ipsilateral part of the dorsal column.

Fasciculus cuneatus: appears at the level of T6 and contains the axons that enter the cord ipsilaterally at the upper six thoracic and cervical levels and that are located in the lateral part of the dorsal column.


Conveys proprioception, fine touch, position (kinesthesia) and vibratory senses to the medulla oblongata, where the axons terminate respectively in the nucleus gracilis and the nucleus cuneatus. Conveys impulses concerned with welllocalized
touch and with the sense of movement and position.

Important in moment-to-moment (temporal) and point-topoint (spatial) discrimination.

Makes it possible for you to put a key in a door lock without light or visualize the position of any part of your body without looking.

Lesions to the tract from destructive tumors, hemorrhage, scar tissue, swelling, infections, direct trauma, etc. abolish or din1inish tactile sensations and movement or position sense.

The cell bodies of the primary neurons in the dorsal column pathway are in the spinal ganglion. The peripheral processes of these neurons begin at receptors in the joint capsule, muscles, and skin (tactile and pressure receptors).


Helps mediate the sensations of pain, cold, warmth, and touch from receptors throughout the body (except the face) to the brain.

Lateral spinothalamic tract,Ventral spinothalamic tract


Most of the cells project to the contralateral thalamus, although a small fraction project ipsilaterally.;

Conveys information about pain and temperature sensations.

Conveys information about pressure and simple touch.

As the spinothalamic tract ascends, it migrates from a lateral position to a posterior-lateral position. In the midbrain, the tract lies adjacent to the medial lemniscus. The axons of the secondary neurons terminate in one of a number of centers in the thalamus.



Convey messages with regard to deep and d1fonic pain to reticular formation of the brainstem by diffuse, polysynaptic pathways.

The spinocerebellar tract conducts impulses related to the position and movement of muscles to the cerebellum. This information enables the cerebellum to add smoothness and precision to patterns of movement initiated in the cerebral hemispheres. Spinocerebellar impulses do not reach the cerebrum directly and therefore, have no conscious representation.


Uncrossed and more numerous than those of anterior spinocerebellar tract. They arise from the dorsal nucleus of Clarke and ascend as a posterolateral tract to enter the cerebellum through the inferior cerebellar peduncle and terminate in the anterior lobe and part of the pyramis.


Mostly concerned with proprioceptive information from the upper limbs and with the control of posture.


Fibers from the anterior spinocerebellar tract ascend from the lower cord and are divided into a few ipsilateral (uncrossed) and a majority of contralateral (crossed) fibers.


Mostly concerned with proprioceptive information from the lower limbs and with the control of posture.


Afferent fibers from the temporal, parietal, OCCipital, and frontal lobes of the cerebral cotrex pass through the internal capsule and crus cerebri and synapse in the pontine nuclei. From here, the fibers enter the cerebellum through the middle cerebellar peduncle and terminate in the contralateral cerebellar hemisphere.


Provides motor information to the cerebellum from the frontal lobe.


Afferent fibers from the temporal, parietal, occipital, and frontal lobes of the cerebral cortex pass through the internal capsule and synapse in both the ipsilateral and contralateral inferior olivary nuclei. From here, the fibers enter the cerebellum through the inferior cerebellar peduncle and terminate in the contralateral cerebellar hemisphere. Note: This pathway differs from all other afferents in that its fibers terminate in the cerebellum as climbing fibers, whereas all other afferents terminate as mossy fibers.


Concerned with muscle-joint information

Afferent fibers from all over the cerebral cortex terminate in the pontine and medullary reticular formation, both ipsilaterally and contralaterally. From here, the fibers enter the cerebellum through the middle cerebellar peduncle and terminate in the ipsilateral cerebellar hemisphere.


Concerned with muscle-joint information.


Afferent fibers from the lateral cuneate nucleus in the medulla enter the cerebellum through the inferior cerebellar peduncle and terminate in the ipsilateral cerebellar hemisphere.


Concerned with muscle-joint information


Afferent fibers of the vestibular system project to the cerebellum in two ways. Primary vestibular afferents project directly to the ipsilateral cerebellar hemisphere (primarily to the flocculonodular lobe) through the inferior cerebellar peduncle. Other vestibular afferents first synapse in the vestibular nuclei, and then also enter the cerebellum through the inferior cerebellar peduncle.


Conveys information from the semicircular canals of the inner ear to the cerebellum via the vestibular nucleus located in the lower pons and medulla. These fibers travel to the flocculi on the inferior cerebellar peduncle.