7神经系统对运动的调节(英文版)

of posture
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Overview

脊髓内的“下运动神经元(Lower neurons)”，除了
受到脊髓内局部环路的影响外，还受到大脑皮层运
动区及脑干中许多“上运动神经元(Upper neurons)”
的支配和协调

基底神经节和小脑则向那些上运动神经元提供某种
感觉、认知或感性的信息，使运动更加精确和协调
30 mixed spinal nerves cervical 1-8 thoracic 1-12 lumbar 1-5 sacral 1-5
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The distribution of motor neurons in the spinal cord
Segments C3-T1 have a swollen ventral horn that innervate skeletal musculature in arms Segments L1-S3 have a swollen ventral horn that innervate skeletal musculature in legs The cervical enlargement of the spinal cord contains the motor neurons that innervate the arm muscles The lumbar enlargement contains
Central Nervous System Control of Movement
XING, GUOGANG(邢国刚), MD. Ph.D.
北京大学 神经科学研究所
Neuroscience Research Institute, Peking University
Email address: ggxing@bjmu.edu.cn
off”
The rhythmic movements could be elicited in the hind legs of cats and dogs long after their spinal cords had been severed from the rest of the central nervous system
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Lou Gehrig Farewell Speech:
"Fans, for the past two weeks you have been reading about the bad break I got. Yet today I consider myself the luckiest man on the face of this earth. ……So I close in saying that I may have had a tough break, but I have an awful lot to live for."
支配躯干部肌肉的神经元位于脊髓前角灰质最
内侧，由此向外排列的神经元则支配肢体由近 及远分布的肌肉
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下运动神经元的损伤表现

Muscle weakness and paralysis－所支配的骨骼肌瘫痪、
肌张力下降、腱反射消失(软瘫)

肌萎缩、纤维颤动或肌束颤动 见于如肌萎缩侧索硬化症(amyotrophic lateral sclerosis, ALS)：Selective damage to alpha motor neurons(degeneration)－脊髓-运动神经元的进行性 溃变为主
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Spinal motor neurons



Alpha motor neurons Innervate skeletal muscle (extrafusal muscle) Function: directly command muscle contract Lower motor neurons Gamma motor neurons Innervate muscle spindle (intrafusal muscle) Function: regulating the muscle spindle Interneurons Allows coordinated motor programs to be generated
Final common pathway
(directly command muscle contract) • Compare: Upper motor neurons
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The Lower Motor Neurons
－ Alpha motor neurons

Alpha motor neurons are directly responsible for the generation of force by muscle Motor unit: one alpha motor neuron and all of the muscle fibers it innervates collectively make up motor unit, the elementary component of motor control Motor neuron pool: The collection of alpha motor neurons that innervates a single muscle
4
The motor control hierarchy have three levels


The ቤተ መጻሕፍቲ ባይዱighest level－ strategy
Represented by the association areas of neocortex and basal ganglia of the forebrain
of the leg
支配上肢的神经元集群位于颈膨大处，支配下肢的则在腰膨大处
Whereas those innervating axial musculature are found at all levels
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The distribution of lower motor neurons in the ventral horn
3 certain motor programs for
the generation of coordinated movements
These
spinal cord contains
Basal ganglia
Cerebellum
2
Brain stem
The spinal cord’s command and control of coordinated muscle contraction
The motor neurons that innervate distal and proximal musculature are found mainly in the cervical and lumbar-sacral segments of the spinal cord
neurons that innervate the muscles

— •
The middle level－tactics
Represented by the motor cortex and cerebellum Is concerned with tactics The sequences of muscle contractions Arranged in space and time


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A motor unit and motor neuron pool
The motor unit is an alpha motor neuron and all of the muscle
The motor neuron pool is all of the alpha motor neurons that innervate one muscle
–Charles Sherington & Graham Brown (English)

—
The importance of circuitry within the spinal cord for the coordinated control of movements
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Spinal circuitry control of movement
The
brain’s command and
Interneuron - Motorneuron
control of the motor programs in the spinal cord
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Part 1
Spinal Control of Movement
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Introduction

“running around like a chicken with its head cut
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The
motor system consists of
all our muscles and the neurons that command them
The
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Sensorimotor cortex
4
The motor control can be divided into two parts:
•
Required to smoothly and accurately achieve the
strategic goal
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The motor control hierarchy have three levels


The lowest level－ execution
Represented by the brain stem and spinal cord
—
Is concerned with execution Action of the motor neuron and interneuron pools that generate the goal-directed movement and make any necessary adjustments
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Muscle innervation by lower motor neurons
The ventral horn of the spinal cord contains motor neurons that innervate skeletal muscle fibers
Ventral roots + Dorsal root = Spinal nerve
programs are
accessed, executed, and modified by descending commands from the brain
Receptors muscle, skin, joint Motor unit (final common pathway)
1
Spinal cord
Motor neurons controlling flexors lie dorsal to those controlling extensors Motor neurons controlling axial muscles lie medial to those controlling distal muscles

Is concerned with strategy:
—
The goal of the movement and the movement
strategy that best achieves the goal
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The motor control hierarchy have three levels
1
Introduction
生命在于运动…… 运动是动物维系个体生存和种
族繁衍的基本功能之一
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How does a coordinated movement achieved ?
3
A baseball pitcher planning a pitch…
The mental body image seems to be generated by somatosensory, proprioceptive, and visual inputs to the posterior parietal cortex (area 5, area 7)