Brain

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Blood vessels

C ranial base

C ra n ia l nerves

M eninges

P arts of the brain

Pathways of the spinal cord

Fibrae thalamoparietales

Fibrae thalamoparietales

N trigeminus [V]

Nuclei nervi trigemini

Decussatio lemniscorum

Nucleus gracilis

Fasciculus gracilis

Fasciculus cuneatus

Nucleus cuneatus

-Tractus spinothalamicus lateralis

-Tractus spinothalamicus anterior

-Tractus spinoreticularis

-Tractus spinotectalis

-Tractus spinoolivaris

y

(Fasciculus

' anterolateralis)

Gyrus postcentralis

Gyrus postcentralis

Lemniscus medialis

Thalamus

Ganglion sensorium

nervi spinalis

Nucleus centralis

N spinalis

Fig. 613

Pathways for epicritic (blue) and protopathic (green) sensibility.

Ascending pathways

Pathway for epicritic sensibility (tactile pathway)

(Precise differentiation of pressure and touch)

1

.

neuron (uncrossed)

From receptors (exteroceptors) in the skin and the mucosa, as well as the periosteum, the joints and the muscle

spindles etc., to the cuneate and gracile nucleus in the medulla oblongata: gracile and cuneate fasciculus (perikarya

in the spinal ganglia): descending collaterals (see Fig. 612)

2

neuron (crossed)

From the medulla oblongata (cuneate and gracile nucleus) to the thalamus (medial lemniscus, perikarya in the

cuneate and gracile nucleus)

3

neuron (uncrossed) From the thalamus to the cerebral cortex, particularly to the postcentral gyrus (thalamocortical

fibres, perikarya in the thalamus).

Pathway for protopathic sensibility (pain pathway)

(Pain, temperature, general pressure sensation)

1

neuron (uncrossed)

From receptors (exteroceptors) of the skin and the mucosa etc., to the posterior horn, laminae l-V (perikarya in the

spinal ganglia)

2

neuron (crossed, some fibres possibly uncrossed)

From the posterior horn to the thalamus, in the reticular formation and to the midbrain tectum (anterior and lateral

spinothalamic tracts, spinoreticular tract, spinotectal tract; perikarya in the posterior column).

3

neuron (uncrossed)

From the thalamus among others to the cerebral cortex, particularly to the postcentral gyrus (thalamocortical fibres,

perikarya in the thalamus).