功能性神經解剖學 Chapter 18. Overview of Motor System Chapter 19. Basal Ganglia 99/12/24(五)

Chapter18 Overview of Motor Systems

Each Lower Motor Neuron Innervates a Group of Muscle Fibers, Forming a Motor Unit Figure 18-1 The muscle fibers of a single motor unit (type FR) in cat gastrocnemius.

Figure 18-2 Arrangement of motor neurons at C8.

Lower Motor Neurons Are Arranged Systematically Figure 18-3 Relationships between action potentials in lower motor neurons (A), action potentials in a postjunctional muscle fiber (B), and force production by the muscle fiber (C). (Modified from Nolte J: Elsevier's integrated neuroscience, Philadelphia, 2007, Mosby Elsevier.) © 2005 Elsevier

There Are Three Kinds of Muscle Fibers and Three Kinds of Motor Units Figure 18-4 Demonstration of fiber types in cross sections of human skeletal muscle biopsies, and some characteristic changes that accompany neuropathology.

Motor Units Are Recruited in Order of Size Figure 18-5 S (first column), FR (second column), and FF (third column) motor units of cat gastrocnemius, showing the anatomical components (A), twitch response to a single stimulus (B), and responses to intermittent bursts of action potentials (C) for each. The same time and force scale applies to all three twitches in B. (B and C, modified from Burke RE et al: J Physiol 234:723, 1973.)

Figure 18-6 Recruitment of motor units in order of size. © 2005 Elsevier

Figure 18-7 Major components and schematic connections involved in motor control.

Motor Control Systems Involve Both Hierarchical and Parallel Connections Figure 18-8 Principal locations and projections of upper motor neurons.

Figure 18-9 Ataxia caused by a somatosensory deficit.

The Corticospinal Tract Has Multiple Origins and Terminations Figure 18-10 Location, extent, and somatotopic arrangement in motor areas of cerebral cortex

Corticospinal Axons Arise in Multiple Cortical Areas Figure 18-11 Projection of premotor and supplementary motor areas to primary motor cortex, and of all three motor areas to the brainstem and spinal cord.

Motor Control Systems Involve Both Hierarchical and Parallel Connections Figure 18-12 The path of axons leaving primary motor cortex, demonstrated with diffusion tensor imaging.

Figure 18-13 Typical somatotopic arrangement of corticospinal fibers in the posterior limb of the internal capsule.

Figure 18-14 Participation of the supplementary motor area, premotor cortex, and parietal association cortex in planning movements.

Figure 18-15 Selective weakness of lower facial muscles after cortical damage.

Figure 18-16 Terminations of corticospinal axons (labeled by axoplasmic transport of a marker) in two species of monkey-one that does not use individual finger movements (squirrel monkey), and one that does (cebus monkey).

There Are Upper Motor Neurons for Cranial Nerve Motor Nuclei Figure 18-17 Biceps electromyograms from normal (A) and spastic (B) subjects in response to a 30-degree extension at the rates indicated.

Figure 18-18 Corticobulbar pathway

Chapter19 Basal Ganglia

Figure 19-1 Basal ganglia and surrounding structures, as seen in an axial section.

The Basal Ganglia Include Five Major Nuclei Figure 19-2 Basal ganglia and surrounding structures, as seen in coronal sections. The ansa lenticularis is an output bundle leaving the globus pallidus (see Fig. 19-15). A, anterior nucleus (of the thalamus); Am, amygdala; CCb, body of the corpus callosum; D, dorsomedial nucleus; HC, hippocampus; Ia and Ip, internal capsule-anterior limb and posterior limb; Ins, insula; LVa and LVb, anterior horn and body of the lateral ventricle; O, optic tract; VA, VL, and VP, ventral anterior, ventral lateral, and ventral posterior nuclei. (Adapted from Nolte J, Angevine JB Jr: The human brain in photographs and diagrams, ed 3, St. Louis, 2007, Mosby.)

Figure 19-3 Terminology associated with the basal ganglia.

Figure 19-4 Parasagittal section showing how the striatum got its name Figure 19-4 Parasagittal section showing how the striatum got its name. Am, amygdala; HC, hippocampus; Ip, posterior limb of the internal capsule; LVa, atrium of the lateral ventricle; Th, thalamus. (Adapted from Nolte J, Angevine JB Jr: The human brain in photographs and diagrams, ed 3, St. Louis, 2007, Mosby.)

The Striatum and Globus Pallidus Are the Major Forebrain Components of the Basal Ganglia Figure 19-5 Three-dimensional reconstruction of the striatum and globus pallidus inside a translucent CNS.

The Subthalamic Nucleus and Substantia Nigra Are Interconnected with the Striatum and Globus Pallidus Figure 19-6 The compact (SNc) and reticular (SNr) parts of the substantia nigra.

Basal Ganglia Circuitry Involves Multiple Parallel Loops That Modulate Cortical Output Figure 19-7 Principal inputs to and outputs from the basal ganglia.

Figure 19-8 Parallel loops through the basal ganglia

Interconnections of the Basal Ganglia Determine the Pattern of Their Outputs Figure 19-9 Major connections of the striatum.

The Cerebral Cortex, Substantia Nigra, and Thalamus Project to the Striatum Figure 19-10 Medial (A) and lateral (B) views of the left striatum, reconstructed from magnetic resonance imaging (MRI) scans, showing the somatotopic representation of body parts.

Figure 19-11 Chemical compartmentalization of the striatum.

The External Segment of the Globus Pallidus Distributes Inhibitory Signals within the Basal Ganglia Figure 19-12 Contrast-enhanced computed tomography scans immediately after the 3-day disappearance of the patient described in Box 19-1

The Internal Segment of the Globus Pallidus and the Reticular Part of the Substantia Nigra Provide the Output from the Basal Ganglia Figure 19-13 Major connections of the external segment of the globus pallidus (GPe);

The Subthalamic Nucleus Is Part of Additional Pathways through the Basal Ganglia Figure 19-14 Major afferents to (A) and efferents from (B) the internal segment of the globus pallidus (GPi) and the reticular part of the substantia nigra (SNr).

Figure 19-15 Efferents from the globus pallidus, seen in coronal sections.

Figure 19-16 Subthalamic fasciculus as seen in an axial section.

Figure 19-17 Major connections of the subthalamic nucleus (STN).

Many Basal Ganglia Disorders Result in Abnormalities of Movement Figure 19-18 Axial magnetic resonance imaging (MRI) scans of a 29-year-old man with Huntington's disease

Figure 19-19 Hemiballismus Figure 19-19 Hemiballismus. A, A 65-year-old HIV-positive man developed, over the course of several months, "unintentional, forceful flinging movements of his right arm and leg

Figure 19-20 The midbrain of a patient with Parkinson's disease, showing loss of pigmentation in the compact part of the substantia nigra (*)

Anatomical and Neurochemical Properties of the Basal Ganglia Suggest Effective Treatments for Disorders Figure 19-21 One model that uses some of the excitatory (green) and inhibitory (red) interactions in the basal ganglia to explain how they might function together to affect cortical output in health and disease.

Figure 19-22 Increased blood flow in the supplementary motor area (S) and premotor cortex (P) of Parkinson's disease patients during movement following treatment with l-dopa.

Figure 19-23 Improvement in motor system function of Parkinson's disease patients following unilateral pallidotomy.