The Motor Pathways 运 动 传 导 路

upper motor neuron 上运动神经元 lower motor neuron 下运动神经元 The motor pathways are concerned with motor function, include pyramidal system 锥体系 extrapyramidal system 锥体外系 upper motor neuron （一） Pyramidal System 锥体系 It concerned with voluntary movement 随意运动of the skeletal m. and is composed of two orders of neurons: upper motor neuron 上运动神经元 lower motor neuron 下运动神经元 lower motor neuron effector

lie in the motor area of cerebral cortex, Upper Motor Neurons upper motor neuron lie in the motor area of cerebral cortex, Connect directly or through interneurons to lower motor neurons, Lower Motor Neurons include cranial motor nuclei and motor neurons in anterior horn of spinal cord. their axons leave the CNS and extend though peripheral nerves to supply skeletal muscles lower motor neuron The pyramidal system consists of corticospina tract 皮质脊髓束 corticonuclear tract 皮质核束 effector

Corticospinal tract upper motor neuron upper motor neuron is the Giant pyramidal cells (Betz cells) 巨大锥体细胞 and other pyramidal cells in superior 2/3 of precentral gyrus and ant. part of paracentral lobule Corticospinal tract Decussation of pyramid Lateral corticospinal tract Anterior corticospinal tract Lower motor neuron

1. Corticospinal Tract 皮质脊髓束 Lower motor neuron is the Motor neurons of anterior horn of spinal cord Lateral corticospinal tract Motor neurons of anterior horn Anterior corticospinal tract

2.Corticonuclear Tract 皮质核束 Giant pyramidal cells and other pyramidal cells in lower 1/3 of precentral gyrus Cranial motor neuclei 脑神经运动核 upper motor neuron Corticonuclear Tract Genu of internal capsule Brain stem lower motor neuron Cranial nerves Skeletal m. of the head ,neck and face.

The Corticonuclear tract send out fibers to end Bilateral： nucleus of oculomotor n., nucleus trochlear n., motor nucleus of trigeminal n., nucleus of abducent n. ambiguus nucleus, nucleus of accessory n. superior part of facial nucleus. facial nucleus Contralateral: inferior part of facial nucleus 面神经核下半 hypoglossal nucleus 舌下神经核. hypoglossal nucleus

Corticonuclear tract facial nucleus hypoglossal nucleus and inferior part of facial nucleus receive only the fibers from the contralateral corticonucleal tract. hypoglossal nucleus

The injury of the unilateral corticonuclear tract can usually cause the paralysis of the contralateral glossal m. and facial m. below the palpebral fissure. The paralysis caused by the injury of the upper motor neuron is called supranuclear paralysis 核上瘫; The paralysis caused by the injury of the lower motor neuron is called the infranuclear paralysis 核下瘫

infranuclear paralysis of facial n. 面神经核下瘫 supranuclear paralysis of facial n. 面神经核上瘫 ---- the paralysis of facial m. in opposite side below the pelpebral fissure 对侧睑裂以下面肌瘫痪 infranuclear paralysis of facial n. 面神经核下瘫 ---- the paralysis of facial m. of same side 同侧面肌瘫

supranuclear paralysis of hypoglossal n.舌下神经核上瘫 ----when tongue extend, the apex of tongue inclined to the opposite side infranuclear paralysis of hypoglossal n. 舌下神经核下瘫 ----when tongue extend, the apex of tongue inclined to the same side

Effects of Upper and Lower Motor Neuron Damage   UMN damage ( supranuclear paralysis ) LMN damage ( infranuclear Paralysis Spastic 痉挛性（硬瘫） Flaccid 软瘫 Muscle tone 肌张力 Increased↑ Decreased↓ tendon reflexes 腱反射 Decreased ↓ Pathological reflexes病理反射 Positive (＋) Negatively (－) Amyotrophy 肌萎缩 No present Distinctly 明显

（二） Extrapyramidal System 锥体外系 composision：the extrapyramidal System include the following structures Cerebral cortex、corpus striatum 纹状体、dorsal thalamus、subthalamus、red necleus、substantia nigra、pontine neuclei脑桥核、vestibular neuclei、cerebelum、reticular formation and the fibers connection among them.

（二） Extrapyramidal System 锥体外系 2. character ①发生古老，在鸟类以下是控制运动的中枢。 ②结构复杂、纤维联系广泛，因此是多级神经元的传导通路 ④ 在功能上与锥体系是统一的整体，锥体系功能的实现有赖于锥体外系保证稳定的肌张力,而锥体外系功能的实现也需要依赖锥体系的发动。 ③ 主要参与调节肌张力、协调肌肉活动、维持体态姿势和习 惯性动作。

1、The cortico-neosstriated body-dorsothalamus –cortex circuit 皮质—新纹状体—丘脑—皮质环路 对皮质运动区有反馈调节作用 2、The neostriated body-subsantia nigra circuit 新纹状体—黑质环路 多巴胺能通路，损伤可致震颤麻痹

3、the corticoponto-cerebellar-cortex circuit 皮质- 脑桥 - 小脑 - 皮质环路 协调随意运动，损伤表现共济失调

4. 锥体系损伤及表现： ①脊髓前角及脊神经损伤： 软瘫 flaccid paralysis ②脊髓外侧索损伤： 同侧损伤平面以下硬瘫 hard paralysis ③延髓锥体交叉以上处损伤： 如内囊损伤 对侧上、下肢硬瘫

1. Injury of the internal capsule

1. Injury of the spinal cord

3. Upper、Lower Motor Neurons 上、下运动神经元 ① Upper motor Neurons: 指大脑皮质的锥体细胞及其轴突 ② Lower motor Neurons: 指脊髓前角细胞和脑神经运动核细胞 ③上运动神经元损伤（核上瘫 supranuclear paralysis)：在皮质脊髓束表现为硬瘫(hard paralysis), 即 肌张力(tonicity of muscles)增高、肌肉不萎缩(without atrophy)、深反射亢进、出现病理反射等；在皮质核束表现为：即对侧眼裂以下的面肌瘫痪和舌肌瘫痪（伸舌时舌尖偏向对侧）。 ④下运动神经元损伤（核下瘫 infranuclear paralysis)：在皮质脊髓束表现为 软瘫 ( flaccid paralysis or soft paralysis). ， 即肌张力降低、肌肉萎缩(muscles atrophy) 、深、浅反射消失、无病理反射等；在皮质核束表现为：即同侧全部面肌瘫痪和舌肌瘫痪（伸舌时舌尖偏向同侧）。