Download The Subconscious Motor Tracts

Section of Spinal Cord Lab I and II
神經科學實驗:脊隨
王昭穎 助理教授
國防醫學院生物及解剖學科
[email protected]
18713
General Organization

The spinal cord is housed within the vertebral
column
General Organization

There are 31 segments in
the spinal cord:
8 cervical (C1 - C8)
 12 Thoracic (T1 - T12)
 5 Lumbar (L1 - L5)
 5 Sacral (S1 - S5)
 1 Coccygeal

The Spinal Cushing system(Meninges)
General Organization
Cross Section of The Spinal Cord
Cross Sectional Organization
Sectional Anatomy of the Spinal Cord


Gray matter
 Central canal
 Consists of somas (cell bodies) surrounding the
central canal
White matter
 Consists of axons
 Nerves are organized into tracts or columns
 Located outside the gray matter area
Cord Sections -- Cervical

Cervical cord is wide, flat,
almost oval in appearance
Cord Sections -- Cervical Enlargement
Cervical
Cervical Enlargement
Cord Section -- Thoracic



Less white matter than
cervical
Rounder appearance
Less prominent ventral
horns than cervical
enlargement
Cord Section -- Lumbar
Lumbar



Less white matter than
thoracic
Rounder appearance
Larger ventral horns,
especially in lumbar
enlargement
Lumbar Enlargement
Cord Section -- Sacral



The proportion of gray
matter is largest
Not much white matter
The diameter of the
spinal cord is the
smallest
Gray Matter: Functional Organization
Rexed’s lamina(layers)-Dorsal horn




Lissauer’s tract (dorsolateral fasciculus)
Lamina II, is called the substantia gelantinosa
Lamina III & IV form what is also called the nucleus proprius
Lamina VII (C8-L3) the Clarke's column, (or the nucleus thoracic or dorsalis),
origin of the spinocerebellar tract
Rexed’s lamina(layers)-Vental horn

Lamina IX: alpha and gamma motor neurons
Grey Matter: Posterior Horn

Mostly Interneurons
 Substantia gelatinosa
 Pain/temp proc

Body of the posterior
horn
 Sensory proc
Grey Matter: Intermediate Grey


Clarke’s Column
 T1-L3
 Balance/proprio.
Intermediolateral
Column
 T1-L3
 Sympathetic neurons
Grey Matter: Anterior Horn

Lower Motor
Neurons
White Matter
Sensory Pathway Neuron Definition
Three major pathways carry sensory information
1. Posterior column pathway
2. Spinothalamic (Anterolateral) tract
3. Spinocerebellar(Anteroposterior) tract
1.
3.
2.
1.Posterior column pathway




Carries fine touch, pressure and proprioceptive sensations
Axons ascend within the fasculus gracillis and cuneatus
 Fasciculus gracilis
 Transmits information coming from areas inferior to T6
 Fasciculus cuneatus
 Transmits information coming from areas superior to T6
Decussation in medulla oblongata
Relay information to the thalamus via the medial lemniscus
2.Spinothalamic pathway

Headed toward the ventral nuclei of the thalamus

Carries poorly localized sensations of touch, pressure(anterior), pain
and temperature(lateral)

Axons decussate first in the spinal cord then ascend
Spinothalamic pathway
3.Spinocerebellar pathway


Include the posterior and anterior
spinocerebellar tracts
Carries sensation to the cerebellum
concerning position of muscles, tendons
and joints
White Matter
Motor pathways and Descending Tracts



Originate from the cerebral cortex and brain stem
Concerned with:
 Control of movements
 Muscle tone
 Spinal reflexes and equilibrium
 Modulation of sensory transmission to higher
centers
The motor pathways are divided into two groups
 Direct pathways (voluntary motion pathways)
 The pyramidal tracts (corticospinal)
 Indirect pathways (postural pathways)
 The extrapyramidal pathways
The Corticospinal Tract

Originate in the pyramidal neurons in the precentral gyri.

Concerned with voluntary, discrete, skilled movements.

Impulses are sent through the corticospinal tracts and
synapse in the contralateral side of anterior horn.

Part of the direct pathway, called corticobulbar tracts,
innervates cranial nerve nuclei.
Axons
pass through corona radiata,
internal capsule, crus cerebri and
pyramid of medulla oblongata.
In
the caudal medulla about 75-90% of
the fibers decussate and form the
lateral corticospinal tract.
Rest
of the fibers remain ipsilateral
and form anterior corticospinal tract.
They also decussate before
termination.
Other Motor Tracts
√
Voluntary Motor
√
√
√
The Subconscious Motor Tracts

Consists of four tracts involved in monitoring the
subconscious motor control
 Vestibulospinal tracts
 Tectospinal tracts
 Reticulospinal tracts
 Rubrospinal tracts
The Subconscious Motor Tracts
Vestibulospinal tracts


Send information from the inner ear to
monitor position of the head
Vestibular nuclei respond by altering muscle
tone, neck muscle contraction, and limbs for
posture and balance
Vestibulospinal tracts
The Subconscious Motor Tracts
Tectospinal tracts


Send information to the head, neck, and upper
limbs in response to bright and sudden movements
and loud noises
The tectum area consists of superior and inferior
colliculi
 Superior colliculi: receives visual information
 Inferior colliculi: receives auditory information
Tectospinal tracts
and
Rubrospinal tracts
The Subconscious Motor Tracts

Rubrospinal tracts


Send information to the flexor and extensor
muscles
Reticulospinal tracts

Send information to cause eye movements and
activate respiratory muscles
Reticulospinal tracts
Ascending and Descending Tracts
Spinal Cord Blood Supply
Ventral
Dorsal
Spinal Cord Blood Supply
Checking list
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
Which segment of spinal cord(C, T, L, or S)
Caudal equina
Filum terminalis
Denticulate ligament
Conus medullaris
Ventral median fissure
Dorsal median sulcus
Dorsal intermedian sulcus
Dorsal lateral sulcus
Central canal
Posterior root ganglion
Spinal nerve
Dorsal horn and Ventral horn
Anterior spinal artery
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.
25.
26.
27.
28.
29.
30.
Artery of Adamkiewicz
Posterior spinal artery
Anterior and Posterior radicular arteries
Lissauer’s tract (dorsolateral fasciculus)
Substantia gelatinosa--- Rexed’s laminae I-II
Nucleus proprius--- laminae III-IV
Doral column (Fasciculus gracilis and cuneatus)
Clarke’s column (T1-L3)---Rexed’s laminae VII
Spinothalamic tract (anterior and lateral)
Fasciculus proprius
Spinocerebellar tract (anterior and posterior)
Rubospinal tract
Corticospinal tract (lateral and ventral)
Tectospinal tract
Reticulospinal tract (lateral or medullary; medial or pontine)
Vestibulospinal tract