The Mechanism Of Movement And Direction Of Our Legs
A majority of the students get to class by walking through the campus; I am no exception. This might appear as a simple task, getting from point A to B, utilizing the basic movement of the two legs; but underneath, this process is much more complex than we can possibly imagine. The fact that we are able to control the movement and direction of our legs, our perception and memory of the path we take to reach the building that holds our class, and the many other unpredicted events that occur midway are due to many underlying processes that are active throughout our bodies. From the efforts of the encompassing nervous systems to the miniscule neurons and neurotransmitters within these very systems, all these work in unison to allow for the simple task of a student walking to class.
Our central nervous system (CNS), consisting of the brain and spinal cord, is one of the major reasons we are able to control and feel movement in our bodies. Each step we take with our legs, requires thousands of nerves and signals that are first directed from the primary motor cortex (M1). Located in the front lobe of the cerebral cortex, “M1, is one of the principal brain areas involved in motor function. ” This part of the brain, alongside the primary somatosensory cortex directs movements of our legs by generating nerve impulses that are directed to skeletal muscles on the opposite side of the body. Therefore, in order to take a step using our right leg, our brain’s left hemisphere M1 has to first generate a signal before any of the other steps. At the same time, within our CNS, we have to utilize the occipital lobe. Located in the back of the head, it is essential for vision and our visual memory. As our eyes take in visual information, the occipital lobe processes this information and sends a signal back to our eyes so that we are able to correctly perceive the image placed upon us. If the occipital lobe is damaged, this could lead to cortical blindness – partial blindness – where visual disabilities are bound to appear. Therefore, only with a working occipital lobe and various other parts of the CNS working in unison, only then is one able to successfully walk to class.
How are these signals within our brains created? This step is attributed to neurons and how they are able to relay messages. The time interval in which a student walks to class, utilizes millions and millions of neurons. As one begins to walk to class, an action potential is fired by a slew of excitatory neurons in which the threshold voltage is surpassed (-55 millivolts). Through a series of sodium-potassium pumps and gates to manipulate the voltage within and without the axon (tunnel in which action potential travels), the action potential reaches the terminal and is then brought to the synapse of that certain neuron. These action potentials cause many neurons to release neurotransmitters into the space between neurons known as the synaptic cleft. As these action potentials build up, a signal from the brain to the nerves that we desire movement is delivered. Specifically for neurons that excite skeletal and muscle nerves, the neurotransmitter Acetylcholine (ACh) is released (Waymire). These excitatory neurotransmitters are then magnified by reaching dendrites of other neurons. As this triggers another action potential, down the axon, again manipulating sodium-potassium pumps, eventually a build up of these action potentials are able to send a direct signal towards the certain leg – on the other side of the body in which the neuron and action potential activity occurred – telling it to move. The signal is transmitted to skeletal and muscle nerves along the leg which sit within the rest of the body not including the brain and spinal cord, known as the peripheral nervous system (PNS).
The peripheral nervous system is also vital to our ability for movement and perception; the PNS consists of “nerves connecting the spinal cord with the rest of the body”. From completely shifting our bodies to even fine movements as moving finger tips, we are relying on the speed and precision of the PNS to perform our daily actions even beyond walking to class. As our brains – filled with neurons that produce neurotransmitters – configure a message, it is signaled along to the white matter within the spinal cord, comprised of myelin and glial cells that speed up the process of transmission, to nerves of the PNS that are connected to induce an action that otherwise would not be possible. Part of our voluntary nervous system, the PNS ultimately connects our CNS’s signal to our desired movements across a multitude of places through our bodies.
The supposedly effortless task of walking, can only be explained by the work of the nervous system within our bodies. Due to its functions, we are able to precisely control our movements, our direction, able to see and remember where we are supposed to go. It is even responsible for minute involuntary functions of our bodies such as blinking and breathing. In essence, without the nervous systems and the components of it, we would not be able to live our everyday lives as we do in this very present.
