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Spinal Cord and Reflexes
Published in Nassir H. Sabah, Neuromuscular Fundamentals, 2020
The modulation of reflexes is implemented primarily by descending tracts, as will be discussed more fully in Section 12.2.5. These tracts, illustrated on the right-hand side of Figure 11.3, are somatotopically organized. Thus, medial pathways control axial muscles, that is, muscles close to the body axis, and are involved in the maintenance of posture and balance as well as coarse control of axial and proximal muscles. These pathways are predominantly under brainstem control and include the vestibulospinal tract, the ventral reticulospinal tract, the tectospinal tract, and the ventral corticospinal tract. On the other hand, lateral pathways control both proximal and distal muscles and are involved in most voluntary movements of arms and legs. These pathways are predominantly under cortical control and include the lateral corticospinal tract, the lateral reticulospinal tract and the rubrospinal tract. Similarly, axons from the premotor cortex terminate mostly in motor pools of proximal limb muscles, whereas axons from the primary cortex and supplementary motor area terminate mostly in the motor pools of the hand and digital muscles.
Human–Machine Force Interactive Interface and Exoskeleton Robot Techniques Based on Biomechanical Model of Skeletal Muscle
Published in Yuehong Yin, Biomechanical Principles on Force Generation and Control of Skeletal Muscle and their Applications in Robotic Exoskeleton, 2020
Human somatic motorium is a perfect control system full of effective information exchanges. For a healthy person, the active voluntary exercise is generated by human brain. More specifically, it is controlled by somatic nervous system (SNS). As illustrated in Figure 4.70, neural signals send the information, such as motion intentions, from upper motor neurons to the ones through corticospinal tract to control the contraction of muscle fibers and finally drive the musculoskeletal system to complete target activities. Meanwhile, human detects motion status, such as muscle contraction velocity, contraction force, and joint angle, through proprioceptors and feedback to CNS to do active or reflective feedback adjustment for human motion [124]. Thus, human somatic motion control system is a typical closed-loop control system with feedback pathway for proprioceptors, which can be seen as the biological foundation of human stable motion [125].
Review of the Human Brain and EEG Signals
Published in Teodiano Freire Bastos-Filho, Introduction to Non-Invasive EEG-Based Brain–Computer Interfaces for Assistive Technologies, 2020
Alessandro Botti Benevides, Alan Silva da Paz Floriano, Mario Sarcinelli-Filho, Teodiano Freire Bastos-Filho
The path involving the transmission from the motor cortex to the muscles is called corticospinal tract14 or pyramidal tract. The transmission occurs directly in the pyramidal tract and indirectly through multiple accessory pathways involving basal ganglia, cerebellum, and several brainstem nuclei. The pyramidal tract originates from pyramidal neurons in layer V of the cerebral cortex of M1 (30%), PMA and SMA (30%), and S1 (40%). The pyramidal tract is mainly composed of motor axons, constituting the volunteer component of the motricity. The pyramidal pathways consist of a single tract, originating in the brain, which is divided into two separate tracts in the spinal cord: the lateral corticospinal tract and the anterior corticospinal tract (Figure 1.7b).
Modeling of hyper-adaptability: from motor coordination to rehabilitation
Published in Advanced Robotics, 2021
Harry Eberle, Yoshikatsu Hayashi, Ryo Kurazume, Tomohiko Takei, Qi An
When humans move their body to perform a task, many parts of the human brain play important roles. Sensory information integrated in the parietal association area of the brain and the network between parietal area, premotor cortex, and primary motor cortex (M1) are involved in planning a motor command. This planned motor command is sent to the brainstem and the spinal cord through the corticospinal tract. Subcortical systems involve low-dimensional motor primitives (known as synergies) to generate muscle activity. When humans learn a new motor skill, these nervous systems are utilized for adaptation. In the normal adaptation, the cerebellum, basal ganglia, and cerebral cortex are thought to play specialized roles in supervised learning, reinforcement learning, and unsupervised learning, respectively [2].