Nervous System SHANDONG UNIVERSITY liu Zhiyu

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Nervous System SHANDONG
UNIVERSITYliu Zhiyu
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Introduction



1.Divisions of nervous system Central
nervous system (CNS) Peripheral nervous
system (PNS)
Telencephalon Diencephalon Cerebellum
Midbrain Pons Medulla oblongata
Brain Stem
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Introduction
(2) Peripheral nervous system (PNS)
Cranial n. (12 pairs) Spinal n. (31
pairs) Visceral n.

Visceral sensory n. Visceral motor n.
Sympathetic part Parasympathetic part
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Introduction
2. Basic terminology in nervous system????
(1) CNS 1) Gray matter collection of
nerve cell bodies and their dendrites,
Cortex Nucleus
the outer layer of gray matter in
cerebrum and cerebellum
A group of nerve cell bodies which have the
same shape and function.
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Introduction
2) White matter collection of nerve fibers,
white color during fresh condition
Medulla Fasciculus ( tract )
a central core of white matter beneath cortex of
cerebrum and cerebellum
a bundle of nerve fibers which have the same
origin, termination, and function
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Introduction
3)  Reticular formation a field of
intermingled grey and white matter , and with
larger or smaller groups of nerve cells occupying
the meshes.
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Introduction
(2) PNS 1) Ganglion
a collection of neuron cell bodies outside the
CNS
2) Nerve a bundle of nerve fibers held together
by connective tissue sheath
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The Spinal Cord

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The Spinal Cord ??

• Position
• lies in vertebral canal
• continuous with medulla
• oblongata at level of
• foramen magnum
• ends at the lower border of L1
• at birth , ends at the level of L3

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The Spinal Cord
2. External features A long cylindrical
structure slightly flattened
anteroposteriorly conus medullaris filum
terminale
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The Spinal Cord

• Two enlargements
• ? Cervical enlargement
• ? Lumbosacral enlargement

• Fissure and sulci
• ? Anterior median fissure
• ? Posterior median sulcus
• ? Anterolateral sulcus
• ? Posterolateral sulcus

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The spinal cord
3. segments of spinal cord A portion of the
spinal cord that gives attachment to a pair of
spinal n. constitutes a segment. 31
segments
Cervical segment 8 Thoracic segment 12
Lumbar egment 5 Sacral segment 5 coccygeal
segment 1
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The spinal cord
Table 1 Relationship of segments of spinal
cord to vertebrae
Spinal segments
Vertebral levels
Lie opposite the corresponding
vertebrae
C1 C4
1 lower in number than corresponding vertebrae
C5T4

2 lower in number than corresponding vertebrae
T5 T8
T9 T12
3 lower in number than corresponding vertebrae
T10T12 L1
Lumber segments Sacral and coccygeal segments
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The spinal cord
4. Internal structures (1) Central canal (2)
Gray matter
Anterior horn (column) Posterior horn (column)
Intermediate zone
(3) White matter

Anterior funiculus Lateral funiculus
Posterior. Funiculus
Ant. white commissure
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The spinal cord
Gray matter 1) Posterior horn (column)

Posteromarginal nucleus Substantia
gelatinosa Nucleus proprius Nucleus thoracicus
(dorsalis) in segments C8L3
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Gray matter
2) Intermediate zone

• Intermediaolateral nucleus
• lies in segments T1L3, containing
• sympathetic preganglionic neurons

• Sacral parasympathetic nucleus
• lies in segments S2S4
• Intermediomedial nucleus
• for sensation of viscera

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Gray matter
3) Anterior horn (column) contain motor neurons
?a-motor neuron larger multipolar
neuron ??-motor neuron smaller neuron,
innervates intrafusal fibers regulating muscular
tonus-
? Renshaws cell
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Gray matter
3) Anterior horn (column)
Two groups of nuclei ? Medial nuclear
group present in most segments of spinal
cord, innervating axial muscles. ? Lateral
nuclear group present only in
cervical and lumbosacral enlargements,
innervating limb muscles
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Gray matter
The laminas
Spinal cord gray matter is arranged in
layers, there are 10 Rexeds lamina
The posterior horn is formed by lamina ? to
?, The intermediate zone corresponding to
lamina ?, The anterior horn is composed
laminae ? and ?, lamina ? is the gray
matter surrounding the central canal.
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The spinal cord
Table 2. Important Subdivision of Spinal Cord
Gray Matter
Region Lamina
Nucleus Posterior horn ?
Marginal layer
?
Substantia gelatinosa
?, ?
Nucleus proprius Intermediate zone
? Nucleus thoracicus
(C8L3)
Intermediolateral nucleus
(T1L3)
Sacral parasympathetic nucleus
(S2S4)
Intermediomedial
nucleus Anterior horn ?
Motor neuron
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White matter
Three kinds of fibers

• Ascending fibers

• descending fibers

• fasciculus proprius

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Ascending (Sensory) Pathways

• Conduct general somatic sensory impulses
• Chains of neurons composed of
• First-, second-, and third-order neurons
• three main ascending pathways
• Dorsal column pathway
• Spinothalamic pathway
• spinocerebellar pathway

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Ascending tracts
Fasciculus gracilis
Fasciculus cuneatus
Posterior spinocerebellar tract()
Anterior spinocerebellar tract
Spinothalamic tract
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Ascending tracts
Fasciculus Gracilis Fasciculus Cuneatus
Conduct Proprioceptive and fine touch sensation
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Ascending tracts
Fasciculus gracilis Fasciculus cuneatus

• Carries sensations of
• Two-point discrimination
• Proprioception
• Pressure
• Vibration

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Ascending tracts

• Fasciculus gracili

Arises from spinal ganglion cell below T5
Terminates the Gracile nucleus

• Fasciculus cuneatus

Arises from spinal ganglion cell above
T4 Terminates the Cuneate nucleus
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Ascending tracts

• Spinothalamic Tract

Conduct Pain, temperature and simple touch
sensation of trunk and limbs
Origin Laminae ?,?? of spinal cord
Termination Dorsal thalamus
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Ascending tracts
Spinothalamic Tract
Conduct Pain, temperature and simple touch
sensation of trunk and limbs
Origin Laminae ?,?? of spinal cord
Termination Dorsal thalamus
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Ascending tracts
Spinothalamic tracts

• Lateral Spinothalamic Tract
• Carries pain and temperature information
• Anterior Spinothalamic Tract
• Carries light touch, pressure

Lateral spinothalamic Tract
Anterior spinothalamic Tract
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Ascending tracts

• Posterior. Spinocerebellar

Carries subconscious proprioceptive sensations
to cerebellum
Origin nucleus thoracicus Termination
Cerebellum

• Anterior. Spinocerebellar

OriginLaminae?? Termination Cerebellum
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dscending tracts

• Corticospinal tract
• Arises from the cerebral cortex Terminates in
  the motor neurons of spinal cord, it divided into
  two tract

Lateral Corticospinal
Anterior corticospinal
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dscending tracts ?????

• Lateral Corticospinal

• Anterior corticospinal

Function control somatic voluntary movement
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• Rubrospinal Tract

• Begins in the red nucleus, which is located at
  the midbrain and synapse with lower motor neurons
  in the Laminae ?? of the spinal cord.

• Injury to this structure impairs forearm and
  hand movements, but doesnt greatly affect
  general body movement

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Vestibulospinal
Originate in the vestibular nuclei, and synapse
with lower motor neurons Laminae ?? of the of
the spinal cord.

• Receive major input from the vestibular nerve,
  and the cerebellum

Laminae ??
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? another descending tracts
Reticulospinal
Longitudinal fasciculus
Tectospinal
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The spinal cord
? Descending tracts
Tracts origin
position Termination Function
Lateral Corticospinal
Laminae ??
Cerebral cortex
Lateral Funiculus
Voluntary mov.
Ant. horn
Anterior corticospinal
Cerebral cortex
Ant. Funiculus
Laminae ??
Excite flexor motor neurons
Rubrospinal
Lateral Funiculus
Red nucleus
Laminae ??
Vestibulospinal
Excite extensor motor neurons
vestibular nuclei
Ant. Funiculus
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The spinal cord
? Descending tracts
Tracts origin position
Termination Function
Reticular formation
Reticulospinal
Ant., lateral Funiculus
Laminae ??
Voluntary mov.
Vestibular nuclei
Longitudinal fasciculus
Ant. Funiculus
Condinate neck with eye mov.
Laminae??
Sup. colliculus
Ant. Funiculus
Laminae??
Tectospinal
Spinal cordIntrinsic reflex mechanism of spinal
cord
? Fasciculus proprius
Ant., pos. lateral Funiculus

Spinal cord
Spinal cord
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Ascending tracts
Tract Site of origin Funiculus Termination Function
Fasciculus gracilis Spinal ganglia below segment T5 Posterior Gracile nucleus Convey proprioceptive and fine touch sensation of trunk and limbs
Fasciculus cuneatus Spinal ganglia above segment T4 Posterior Cuneate nucleus Convey proprioceptive and fine touch sensation of trunk and limbs
Posterior spinocerebellar Homolateral nucleus thoracicus Lateral Cerebellum Unconscious proprioception from lower limb and lower portion of trunk
Anterior spinocerebellar Contralateral Laminae ?? Lateral Cerebellum Unconscious proprioception from lower limb and lower portion of trunk
Spinothalamic Laminae ?, ?? Lateral and anterior Dorsal thalamus Pain, temperature and simple touch sensation of trunk and limbs
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Descending tracts
Tract Site of origin Termination Function
Lateral corticospinal Cerebral cortex Laminae ? ? Voluntary movement
Anterior corticospinal Cerebral cortex anterior horn
Rubrospinal Red nucleus Laminae ?? Excitatory of flexors
Vestibulospinal Homolateral vestibular nuclei Laminae ?? Excitatory of extensors
Reticulospinal Reticular formation Laminae ?? Voluntary movement
Fasciculus proprius Spinal cord Spinal cord Intrinsic reflex mechanism of spinal cord
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Function of spinal cord

• Conduction

Convey afferent impulses to the brain conduct
efferent impulses from the brain to the effectors.

• Reflexes the central of the reflex arc.

• Somatic reflex
• stretch reflex
• Visceral reflex
• Reflex of bladder
• Rectal emptying reflex

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Two-Point Discrimination
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Descending Motor Pathways
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The spinal cord
? Ascending tracts
Tract origin
position Termination Function
Fasciculus Gracilis
Spinal ganglia below T5
Gracile nucleus
Proprioceptive and fine touch sensation



Posterior Funiculus
Fasciculus Cuneatus
Cuneate nucleus
Spinal ganglia above T4


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The spinal cord
? ascending tracts
Tracts origin position
Termination Function

Pain, temperature and simple touch sensation
of trunk and limbs
Dorsal thalamus
Spinothalamic Tract
Laminae ?,??
Lateral and ant. Funiculus
subconscious proprioception from lower part of
trunk And lower limb
Posterior. spinocerebellar
nucleus thoracicus
Cerebellum
Lateral Funiculus
Anterior. spinocerebellar
Cerebellum
Laminae??