首都医科大学基础医学院生理学课件第五节 神经系统对姿势和运动的调节.pptVIP

Dynamic response and static response Control of movement at the spinal cord level Spinal shock: In all vertebrates, transection of the spinal cord is followed by a period of spinal shock during which all spinal reflex responses are profoundly depressed. Mechanism of spinal shock The initial shock is considered to be due to the sudden withdrawal of tonic facilitatory influence from the brain Flexion-withdrawal reflex Flexion-withdrawal reflex: The limb is quickly withdrawn from a painful stimulus, usually by simultaneous contraction of all the flexor muscles in the limb. Flexion-withdrawal reflex Polysynaptic reflex Consists of a contraction of flexors and a relaxation of extensors in the stimulated limb Protective reflex Crossed-extension reflex Crossed-extension reflex: An opposite effect in the contralateral limb, that is, excitation of extensor motor neurons and inhibition of flexor motor neurons Posture reflex pathways Lateral motor pathways: voluntary movement Mediate motor pathways: posture reflex Vestibulospinal tracts Reticulospinal tracts Medial Lateral Functional circuitry of the basal ganglia Neostriatum Globus pallidus Subtantia nigra Subthalamic nucleus Basal ganglia Basal ganglia circuit Direct pathway Increase the excitability of cortex Indirect pathway Decrease the excitability of cortex Basal ganglia disorders Parkinson’s disease 帕金森病 Huntington’s disease 舞蹈病与手足徐动症 Pathology of Parkinson’s disease Loss of dopaminergic neurons in the substantia nigra lead to decreased activity in the direct pathway and increased activity in the indirect pathway. As a result, thalamic input to the motor area of the cortex is reduced and the patient exhibits rigidity and bradykinesia. Surgery for Parkinson’s disease Surgery for Parkinson’s disease Functional divisions Polysynaptic reflex Enhance postural support （二）脑干对肌紧张和姿势的调节 去大脑僵直（Decerebrate rigidity） 1、对肌紧张的调节 （1）现象 在中脑上、下叠体（上、下丘）之间切断脑干，动物立即出现四肢伸直、头尾昂起、脊柱挺硬等肌紧张亢进现象（角弓反张）。 去大脑僵