Brain Matter, Motor Pathways, and Nervous System Development
Gray Matter
It is a sensitive character of neuronal nuclei, vegetative and motor. The alpha motor neurons are responsible for innervating the striated or voluntary muscles, and are thus responsible for movement. The gamma motor neurons regulate muscle contraction.
White Matter
Part of clusters of myelinated fibers that circulate in the spinal cord, both upwards and downwards.
Motor Pathways
Motor pathways serve as the main transport facilities for motor skills. They are subdivided into two pathways:
Pyramidal or Main Motor Pathway
The main source of ideokinetic movement. It has D cells in the cerebral motor cortex, placed in the royal postfrontal frontal lobe. It descends through the midbrain and the bump up to the medulla. Its functions are:
- It is the pathway of voluntary or ideokinetic movement: it controls precise and fine muscle movements that run more distantly, e.g., hand movements, finger movements, hip, knee, ankle, and foot movements.
- Inhibition functions of medullary centers. It modulates the intensity of muscle tone reflexes.
Extrapyramidal Pathway
Starts at several centers of conductive integration. Its levels of complexity and functions are:
- Control and tone of involuntary muscle movement and automatic and associated movements.
Transmission of the Nervous System
Neurons
Neurons are the basic units or cells that make up the motor nervous system and are specialized in the transmission of electrical stimulation at high speed and great distance. The human nervous system has 10 billion neurons.
Synapses
The transmission of nerve impulses between neurons forms part of the conduction of the nervous impulse. It is a chain reaction that causes the impulse to travel from the start to the muscle. In this case, the transmission is a fast impulse that is chemical and electrical.
Myelinization
Myelinization is the process of myelin lining the cells of the nervous system. Myelin is a white matter consisting of lipids and proteins. This process begins in the fetus a few months before birth and continues until after birth, around 2-3 years of age. It is the basis of the development of the nervous system. Sufficient stimulation accelerates the myelinization process.
Laws of Motor Development Maturation
The child’s motor development occurs according to these laws:
- Cephalocaudal Law: The evolution of motor development goes from the upper body to the lower body. That is, the child controls the head before controlling the movements of the feet.
- Proximodistal Law: The evolution of motor development goes from the central axis of the body outwards. That is, the child controls the arms before the hands, and the hands before the fingers.
- Law of Flexors and Extensors: First, flexors are used (grab, take, flexing) and then the extensors (jumping or stretching operations). It is the child’s ability to catch something before releasing it.
Types of Movements
Reflexes
Reflexes that disappear are:
- Swallowing
- Yawning
- Sneezing
Reflex movements are spontaneous and involuntary motor responses to an external stimulus. They are innate.
- Respiratory Reflex: Occurs immediately after birth.
- Suction Reflex: Contact of the mouth with an object produces a rhythmic movement of suction.
- Cardinal Points Reflex: Excitement around the corner of the lips causes a rotation of the head in the same direction as the stimulation.
- Grasping Reflex (Pressure): When stimulating the palm of the baby’s hand with a finger or object, the fingers flex and firmly press on the stimulus. The reflex disappears between 2 and 3 months.
- Static Reflex: The tendency to stretch the legs in response to pressure on the soles of the feet. It disappears around 10 months.
- Babinski Reflex: When the sole is touched, the foot bends inwards and the toes open like a fan.
- Moro Reflex: When the baby hears a loud bang or experiences a sudden change in position, the arms are extended and then put back on the chest.
Voluntary Movements
Voluntary movements are those that are conducted intentionally before executing them, for example, early gait and pressure, initiated in hygienic habits.
Automatic Movements
Automatic movements are those repeated voluntary movements that have been transformed into habits. They are intentional but are not executed by thinking about them, for example, walking or driving.