The nervous pathway

SHANDONG UNIVERSITY Liu Zhiyu

一、 Sensory Pathways

1. proprioceptive and fine touch path

way of trunk and limbs

Primary Neuron

Cell bodies are located in the ganglion of spinal n.

transmit sensory input from joint, muscle, tendon to the posterior funiculus of the spinal cord

form the Fasciculus cuneatus and Fasciculus gracilis

1. proprioceptive and fine touch pathway of trunk and limbs

Secondary Neuron

Cell bodies are located in Nucleus gracilis and Nucleus cuneatus

Send out fibers Cross to the opposite by decussation of medial lemniscus

Ascends as medial lemniscus

Third Neuron

cell bodis are located in the thalamus

send out fibers to form central thalamic radiation project to the somatic sensory cortex

1. proprioceptive and fine touch pathway of trunk and limbs

I

II

VPL nucleus

Fasciculus gracilis

Fasciculus cuneatus

Medial lemniscus

III

Nucleus gracilisNucleus cuneatus

Spinal ganglion

Decussation of medial lemniscus

central thalamic radiations

1. proprioceptive and fine touch pathway of trunk and limbs

muscles,tendons,joints and periosteum Peripheral

processes I ipsilateral posterior funiculus of spinal cord

II

Gracile nucleus cuneate nucleus

III

supeior 2/3 of postcentral gyrus and posterior part of the paracentral lobule, Precentral gyrus

central thalamic

radiations

Posterior limb of internal capsule

Spinal ganglion

Central processes

Decussation of medial lemniscus

medial lemniscus

ventral posterolateral nucleus (VPL)

Fasciculus cuneatus (above T4)

Fasciculus gracilis (below T5)

Receptor for fine touch in skin

Pain,temperature and simple touch pathway of trunk and limbs

spinal ganglia

Ⅰ 、Ⅳ、Ⅶ of posterior horn spinothalamic tract

Spinal lemniscus

ventral posterolateral nucleus

central thalamic radiations

I

II

III

Primary Neuron

• Cell bodies are located in the ganglion of spinal n.

• Relay sensory input from the periphery to the posterior horn of the spinal cord

• Synapses with the secondary neurons in the posterior horn of spinal cord

Pain,temperature and simple touch pathway of trunk and limbs

Secondary Neuron

located in the Ⅰ、Ⅳ、Ⅶ of posterior horn of spinal cord

Send out fibers cross to the opposite side through the anterior white commissures and form the spinothalamic tract

Third Neuron

the third neurons located in the thalamus

send out fibers to form central thalamic radiation project to the somatic sensory cortex

Pain,temperature and simple touch pathway of trunk and limbs

Peripheral processes I

II

III

supeior 2/3 of posterior gyrus and posterior part of the paracentral lobule

central thalamic radiations

Posterior limb of internal capsule

Spinal ganglion

Central processes Posterior root

ventral posterolateral nucleus (VPL)

Skin exteroceptor

Pain,temperature and simple touch pathway of trunk and limbs

Ⅰ 、Ⅳ、Ⅶ of posterior horn

lateral spinothalamic tract (pain and temperature)anterior spinothalamic tract (simple touch)

Ascending 1 - 2 segments

Pain, temperature and simple touch pathway of head and face

trigeminal ganglion

pontine nucleus of trigeminal n

spinal nucleus of trigeminal n.

Spinal tract of trigeminal n.

trigeminal lemniscus

ventral posteromedial nucleus (VPM)

central thalamic radiations

I

II

III

Peripheral processes

inferior 1/3 of posterior gyrus

central thalamic radiations

Posterior limb of internal capsule

Central processes

ventral posteromedial nucleus (VPM)

Skin and mucosa of head and face

Pain,temperature and simple touch pathway of head and face

trigeminal ganglion

Trigeminal n.

Root of trigeminal n.

pontine nucleus of trigeminal n.

spinal nucleus of trigeminal n.

II

trigeminal lemniscus

III

I

receptor

cortex of paleocerebellum

Spinal ganglion

（三） visual pathway

receptor

cone cell

rod cell

bipolar cell

Lateral geniculate

bodyOptic Radiation Both banks

of calcarine sulcus

Optic n.

Optic chiasma

ganglion cell

Decussation of fibers from nasal halves of retina

Fibers from temporal halves of retina uncrossed

Optic tract

（三） visual pathway

①

②

③

④

Blindness of eye of corresponding side

bitemporal hemianopia of visual field

Blindness in nasal half of visual field of corresponding side

Homonymous hemianopia of visual field in both eye

Pretectal region

2. pupillary reflexes

retina

Optic n.

Optic chiasma

Optic tract

Brachium of superior colliculus

Pretectal region

accessory nuclei of III

Oculumotot n.

Ciliary ganglion

Postganglionic fibers

Sphincter pupillae

Contraction of pupil

E-W nucleus

Ciliary ganglion

Oculumotot n.

2. pupillary reflexes

The acoustic(auditory) pathway

cochlear ganglion

Spiral organ

cochlear nuclei

medial geniculate body

inferior colliculus

acoustic radiation

The acoustic(auditory) pathway

Spiral organ

cochlear ganglion

Cochlear nerve

cochlear nuclei

Trapezoid body

inferior colliculus

medial geniculate body

acoustic radiation transverse temporal gyriPosterior limb of

internal capsule

Lateral lemniscus

Brachium of inferior colliculus

I

II

VPL nucleus

Fasciculus gracilis

Fasciculus cuneatus

Medial lemniscus

III

Nucleus gracilisNucleus cuneatus

Spinal ganglion

Decussation of medial lemniscus

central thalamic radiations

spinal ganglia

Ⅰ 、Ⅳ、Ⅶ of posterior horn spinothalamic tract

Spinal lemniscus

ventral posterolateral nucleus

central thalamic radiations

I

II

III