The sacral nerves, which are found in the sacrum of the spine and are located below the lumbar nerves, are made up of five pairs (S1 to S5).These nerves are critical in transferring sensory information and controlling motor processes throughout the lower body. The sacral nerves' roles are summarised below:

1. S1: The S1 sacral nerves are mostly responsible for pain in the hips and groyne.They help with sensory perception and motor control in these areas by transferring sensation and allowing movement.

2. S2: The S2 nerves are responsible for the back of the thighs.They are involved in the transmission of sensory information as well as muscular control of this area, allowing movement and sensation.

3. S3: The S3 nerves are responsible for the medial buttocks.They have an effect on sensory perception and motor control in this region, assisting with movement and facilitating sensation transmission.

4. S4 and S5: These nerves are primarily responsible for the perineal area, which includes the genitals and the area between the anus and the genitals. They serve an important function in transmitting sensations and permitting appropriate muscle activity in this region, contributing to sensory perception and motor control.

The sacral plexus is formed when the spinal nerves from the lumbar L4 to the S4 sacral nerves join.This plexus is further subdivided into smaller nerves that transport sensory impulses and control the leg muscles. It is essential for coordinating movement, maintaining balance, and maintaining sensory experience in the lower limbs.

Understanding the sacral nerves' functioning is critical for detecting and treating disorders that can affect these areas, such as hip discomfort, muscle weakness, and sensory problems.These nerves help the lower body operate by aiding movement and providing appropriate sensory feedback.

Medical practitioners can assess and treat sacral nerve disorders, guaranteeing optimal function and enhancing patients' well-being.The sacral nerves must work properly for actions such as walking, sitting, and maintaining bladder and bowel control.

The thoracic nerves, which are placed below the cervical nerves, are made up of 12 pairs (T1 to T12) that are located in the thoracic vertebrae of the spine.These nerves serve an important part in innervating the chest, arms, hands, and abdomen. Here's a rundown of the thoracic nerves' functions:

1. T1 and T2: The upper chest, arms, and hands are supplied by the T1 and T2 thoracic spinal neurons.They aid in sensory perception and motor control by permitting movement and serving feedbacks from the muscles and skin.

2. T3, T4, and T5: These thoracic nerves supply the chest wall and help with breathing.They supply nerve impulses to the intercostal muscles, which are in charge of extending and contracting the rib cage during breathing.

3. T6, T7, and T8 thoracic nerves: These thoracic nerves serve the chest and extend to the belly.They help in motor control and sensory perception in these areas, as well as movements like trunk rotation and stabilisation.

4. T9, T10, T11, and T12 thoracic nerves: These thoracic nerves mostly serve the abdomen and lower back.They provide motor control and facilitate movements such as trunk flexion and lateral bending via innervating the abdominal muscles.They also help with sensory awareness in these areas.

The thoracic nerves serve an important role in transferring sensory information from the chest, arms, hands, and belly to the central nervous system.They also give these muscles motor control, allowing for coordinated movements and functional activities.

Understanding the functioning of the thoracic nerves is critical for diagnosing and treating problems such as chest pain, breathing difficulty, abdominal muscular weakness, and sensory abnormalities that can impact these regions.Thoracic nerve function is critical for sustaining appropriate physical capacities and general well-being.

Cervical nerves are important in managing movement and sensory functions in the head, neck, shoulders, and upper extremities. The following are the primary properties of the cervical nerves:

1. C1, C2, and C3 cervical spinal nerves: These nerves govern head and neck movements. They help with neck flexion, extension, rotation, and lateral bending.

2. C4: The C4 cervical nerve aids in the control of upper shoulder movement. It also helps to power the diaphragm, a vital muscle involved in breathing.

3. C5: The C5 cervical nerve is in charge of coordinating the deltoid muscles in the shoulders and the biceps muscles in the upper arm. Allows for movements such as shoulder abduction and flexion.

4. C6: The C6 cervical nerve is involved in wrist extension control and innervates the biceps muscles. It aids in wrist extension movements and helps stabilise the arm during tasks such as weight lifting.

5. C7: The C7 cervical nerve is mostly connected with the upper arm triceps muscles. It also gives motor control to the muscles that extend the wrist. C7 is essential for elbow extension and wrist stabilisation.

6. C8: The C8 cervical nerve controls the hand muscles, particularly the finger flexors that contribute to handgrip strength. It is essential for fine motor control of the hands and fingers.

Overall, the cervical nerves play an important role in coordinating movement and sensory perception in the head, neck, shoulders, and upper limbs, allowing for a wide range of functions and interactions with the brain.

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The limbic system is one of our brain's earliest regions, according to evolution. According to theories such as the triune brain model, it is also commonly called the emotional brain or emotional nervous system.

Research in the field of neuroscience has provided insight into the roles of the limbic system in behavioral and emotional responses and how it shapes our behaviors. The limbic system can also be called the limbic lobe.

Definition of the Limbic System

Limbic system is a region of the brain that acts as a networking system. With many interconnected parts, it is responsible for controlling a variety of emotional impulses, as well as being instrumental in memory formation. 

The limbic system is made up primarily of the hippocampus, amygdala, thalamus, and hypothalamus. It is situated below the cerebral cortex.

Limbic System  Functions

As mentioned, the limbic system functions as a signaling system to form and contribute to complex emotions and other brain functions such as memory. Despite the limbic system's many components, the point is that they generally work together. For example, although fear is most commonly associated with the amygdala, other brain areas also respond to fear.

Puberty is a crucial stage in the development of the limbic system, as significant changes occur. For example, the amygdala develops more and, combined with hormonal changes, can give rise to intense emotions such as anger, fear and aggression. Furthermore, throughout adolescence, the limbic system comes under greater control from the prefrontal cortex. This area does not fully develop until age 25 and is essential for reasoning, problem solving, and impulse control. The development of the prefrontal cortex is a biological reason why there is a perception that teenagers are moody due to these underdeveloped limbic structures.

Primary structure of the Limbic System

Hippocampus

The limbic system includes the Hippocampus, which comes from the Greek word for seahorse. It is located very deep in the brain and is associated with learning and specific aspects of memory such as spatial memory and spatial navigation.

In terms of memory, memory encoding: the process of allowing information to be encoded, stored and retrieved, is one of its main functions. Memory encoding, for example, might allow us to remember where we had lunch yesterday. Memory consolidation is another aspect of memory that the hippocampus is responsible for, allowing us to form more stable and lasting memories.

Amygdala

The limbic system also includes the amygdala, which is shaped like an almond and is responsible for emotional responses such as pleasure, anxiety, anger, and fear. The amygdala plays a role in memory and is close to the hippocampus in the brain. Specifically, it involves how firmly memories are stored, as memories are often associated with strong emotional ties that tend to stick around for much longer.

The connection between memories and fear is through the amygdala, which can help form new fear-related memories. Learning through fear facilitates the aforementioned concepts such as memory consolidation.

It's an area of ​​the brain that can generate quite intense emotions. Informally, the responses triggered by the amygdala are called "fight or flight," which, combined with the nervous system, is a natural physiological reaction to threats to survival from an evolutionary perspective. There are three distinct stages to the stress caused by these reactions: alarm, resistance, and exhaustion. In particular, much of the research is on the basolateral amygdala.

Thalamus and Hypothalamus

The thalamus is a component of the limbic system and is regarded as the relay station for sensations travelling throughout the body, with the exception of smell (smell) processing. It controls variations in emotional reactivity along with the hypothalamus. Any external event that sets off strong emotions is referred to as emotional reactivity.

One example involves the hypothalamus, which controls vital impulses for the body, such as sleep. In the absence of adequate sleep, other areas of the hypothalamus react. These areas are linked to emotions such as anger, displeasure, and disgust. So there is a clear link between key homeostatic processes such as sleep and emotional communication and the disruption of these processes.

Secondary or accessory brain regions

For brain regions to be regarded as key components, the limbic system's secondary or accessory structures must be present.

The cingulate gyrus is a structure that is close to the nose. This closeness helps associate smells and images with pleasant or adverse memories of past emotions. Also important is the function of the emotional response to pain. Aspects of pain, such as avoiding fear and unpleasant sensations, are processed in this area. Finally, aggressive behavior and impulsivity are also associated, although this is up for debate.

The basal ganglia are a secondary area of ​​the limbic system as they are close to other limbic structures. It is well known for its significance in motor planning and execution. However, recent evidence suggests their roles in reward and reinforcement, addictive behaviors and habit formation. Psychiatric disorders such as depression and schizophrenia may involve a disruption in connections between the basal ganglia and the limbic system. As a result, implications for neuromodulation therapies have been suggested.

Finally, the cingulate gyrus is a structure that, along with processing emotions and regulating behavior, helps regulate autonomic motor function. Its location in the brain is fundamental, as it connects with the frontal, temporal and occipital cortex of the two hemispheres of the brain. Specifically, it coordinates sensory input with emotions. An example would be pricking your finger and then feeling pain. It also deals with the emotional responses associated with pain and regulates aggressive behavior.

Many other areas could be included as additional limbic structures, which suggests the complexity of this area. These include the septum, nucleus accumbens, orbitofrontal cortex, cerebral cortex, olfactory cortex, and many others. There are also subcortical structures to consider.

The Limbic System  and Emotional Responses

At its basic level, affective processing is an activity within the brain that represents decision-making skills. Disruptions to affective cognition are often at the forefront of mood disorders. Many actions and decisions take place in an emotional context. So there is a link between cognitive functions and emotional states. Part of this process is labeling emotions as being positively or negatively valued. For example, emotions like happiness would have a positive valence, and disgust would have a negative valence.

A group of researchers analyzed affective processing abnormalities in criminal psychopaths using magnetic resonance imaging (MRI). They found that affective processing deficits occurred more frequently in response to stimuli with negative valence and that they required more cognitive resources to process and evaluate affective stimuli than the others. Regarding the brain, they found abnormalities in the anterior and posterior cingulum, inferior frontal gyrus, amygdala/hippocampus formation, and ventral striatum. In particular, the abnormalities were related to a lack of affect-related activity in these areas. So there were disturbances in the limbic system.

The Limbic System  and Memory

The "greater limbic system" involves memory function. Specifically, memory is in the sense of organizing behaviors to ensure they are adaptive for survival. 

Affective processing includes memory, affect, and goal-directed behaviour, as was indicated in the preceding section. Long-term memory is a type of memory that can be stored in the brain for years; there are two main groups of long-term memories.

The first is explicit/declarative memories for episodic instances that may occur throughout life. The second type falls into the group of implicit/procedural memories that are important for learning and remembering motor and cognitive skills. Depending on the group, different areas of the limbic system are involved. First, the hippocampus works with another area of ​​the brain called the medial temporal lobe. The second is the basal ganglia, which also work with another vital region of the brain, the cerebellum.

The amygdala does not work alone in memory formation, consolidation, and retrieval of emotional memory functions. The limbic system functions as a neural circuit, whether in declarative memory formation, memory consolidation, contextual fear memory formation, trait conditioning, or conditional discrimination learning.

The Limbic System  and Chronic Stress

Chronic stress can have detrimental impacts on physical and mental health. Chronic stress can be the result of many factors and permanently change the state of the body and mind. Numerous studies on the limbic system have focused on life trauma as a type of persistent stress. One study examined the hypothalamus, specifically the hypothalamic-pituitary-adrenal (HPA) axis. This is a complex set of direct influences and feedback interactions between three structures: the hypothalamus, the pituitary gland, and the adrenal glands on top of the kidneys.

This is a neuroendocrine system, which means that the hormones each of these structures release affect the nervous system as they travel through the blood. Each one releases a hormone that leads to the next one and it's a cascading effect. There is an effect on functions including digestion, the storage and use of energy, and mood in general.

That study found that lifetime trauma significantly affected the HPA axis and that lifetime trauma can make certain limbic regions more sensitive. Specifically, the limbic regions that contain the hippocampus and amygdala. This finding is consistent with research that has found that the amygdala plays a role in influencing the HPA axis for a stress response, triggering the release of stress hormones. This can result in problems with stress regulation and HPA axis function and lead to a risk of poor health outcomes. An example would be impaired memory consolidation. This is a clear example that limbic system dysregulation has a big impact.

Problems Related to the Limbic System

As it develops a series of activities in the human body, the malfunction of the limbic system can lead to various dysfunctions and diseases such as:

• Depression

• Anxiety

• Memory problems (recent or long-term)

• Alzheimer's

• Schizophrenia

• ADHD (Attention Deficit Hyperactivity Disorder)

• Psychomotor Epilepsy

Conclusion

With numerous interrelated components, the limbic system is a complicated network. It has four main components and many additional structures that can be considered secondary - the subcortical structures and the cerebral cortex. Historically, the limbic system was presented as a system within the brain related to emotional states. However, it has recently been explored in relation to its implications for learning and the formation of new memories.

In addition, limbic system disorders and the impacts of chronic stress, as well as strategies to relax the limbic system, were discussed. The aim was to present the limbic system from a broad point of view and recognize how it contributes to well-being as a component of physical and mental health. Finally, stress management techniques are key to keeping this system in check. 

 WHAT IS THE DIENCEPHALON?

The diencephalon derives from the forebrain or forebrain, the most frontal part of the brain in early embryonic development. As the forebrain grows, it divides into the diencephalon and the telencephalon until it becomes a bridge between the midbrain and the telencephalon.

It is located below the corpus callosum and fornix, and joins the hemispheres of the telencephalon on the sides. Therefore, it is located in the middle part of the brain.

Structures in the diencephalon have connections with the rest of the nervous system, including the cortical and subcortical areas. Therefore, it is a center that sends and receives nervous signals (afferents and efferents, respectively) and plays a fundamental role in the proper functioning of multiple biological processes.

FACTS ABOUT THE DIENCEPHALON

The diencephalon is the control center that makes our body maintain its internal balance or homeostasis. We show you some of its curiosities:

• It represents only 2% of the total weight of the nervous system.

• The pituitary is connected to the hypothalamus and is involved in processes such as reproduction and growth through the action of hormones.

• Maintains body temperature.

• Regulates appetite and therefore food intake.

• An area of the epithalamus called the habenula is associated with both fear and depression.

• Regulates the endocrine activity of the adenohypophysis (or anterior pituitary).

• It is the main modulator of the functioning of the Vegetative Nervous System.

THE DIENCEPHALON, STRESS AND EMOTIONS

Additionally, the diencephalon takes involved in the neuroendocrine reactions to stress. In fact, a published study on the relationship between the hypothalamic-pituitary-adrenal axis and stress appears in the journal Dialogues in Neuroscience. It indicates that animals, to respond to stress, activate a range of physiological and behavioural responses associated with this axis.

The authors explain stress as a state of real or perceived threat. As the hypothalamus regulates homeostasis, it manages the situation by working in conjunction with the nervous, endocrine and immune systems.

Likewise, the enormous importance of the hypothalamus in the generation of emotional behaviors has been demonstrated. H. Nakao, in a study published in the American Journal of Physiology, proved that the stimulation of the hypothalamus in cats through implanted electrodes led to aggressive responses.

Thanks to the diencephalon, a little known “great administrator”, communication between cortical and subcortical levels is possible. It also allows us to maintain the balance of our body and the regulation of our emotions, always hand in hand with other systems. A fantastic and efficient control centre.

MAIN STRUCTURAL DIVISIONS OF THE DIENCEPHALON

1. Thalamus

2. Hypothalamus

3. Epithalamus

4. Subthalamus

1. THALAMUS

• It is a mass located in both hemispheres brain.

• Easily visible near the third ventricle.

• Its interior is formed by gray matter (nuclei of neurons) with projections to the cerebral cortex.

THALAMUS – FUNCTIONAL CONSIDERATIONS

• Structure located above the hypothalamus, works as a radio station relay of sensory impulses from the periphery, acting as a “filter” that modulates the information that is sent to the cerebral cortex, as well as reaching the consciousness of the individual.

• Participates in the motor information integration network between the nuclei of the base and cerebellum, and as a relay of motor information to the brain.

• Contrary to what was previously thought, the thalamus not only passes on information to cortex, but it processes higher order information, with the participation of active form in functions usually attributed to the cortex.

• Sensory Functions: The thalamus filters, modulates and distributes all inputs sensory to the various cortical areas.

• Motor functions: It has a relay function between the cerebellum-cortical circuits.

• Emotional functions: Some of its nuclei are part of the limbic system with branches to the prefrontal cortex. Reaction mediation functions to anger, fear and defense.

• Cortical activation function: Some of your nuclei make connection between the reticular activating system and the cerebral cortex. Important functions to protect from some danger or in sleep-wake cycles.

CLINICAL PATHOLOGY OF THE THALAMUS

• A stroke in the arteries supplying the thalamus leads to anesthesia or paresthesia of the opposite half of the thalamic lesion in the individual's body. Being this sense of top of the neck to the tip of the toes. There may be motor difficulties.

• Thalamic pain syndrome: Sensation of pain opposite the thalamic area affected, without peripheral injuries to justify it. This pain is caused dysfunction of the pain pathways that pass through the thalamus.

• Fatal familial insomnia: Rare and hereditary disease, manifests as a result of severe damage to the thalamus. With the cells of this structure destroyed, the individual loses the ability to sleep, dying between six and eighteen months.

2. HYPOTHALAMUS

• It is an important structure for regulating the body's homeostasis.

• Controls the autonomic nervous system as well as all functioning body hormone.

• Much of this regulation is done through its influence on the gland pituitary gland, which secretes the main hormones that stimulate the other glands in the body.

HYPOTHALAMUS – FUNCTION OF THE MAIN NUCLEI

• Supraoptic and paraventricular nucleus: Water balance (regulation of diuresis).

• Suprachiasmatic nucleus: Regulation of the circadian cycle (biological clock).

• Posterior hypothalamic area: Controls the body's conservation of heat.

• Anterior hypothalamic area: Controls body heat loss. 

• Medial preoptic nucleus: Controls blood pressure.

• Ventromedial nucleus: Satiety.

• Mammillary body: Feeding.

HYPOTHALAMUS – THE PITUITARY PHYSIS

• It is also known as the pituitary gland. Having dimensions approx. a pea grain, weighing between 0.5 to 1 gram.

• It is located at the base of the brain, below the hypothalamus, being connected to it by the pituitary stalk or infundibulum.

• It is considered a master gland, because it secretes hormones that control the functioning of other glands.

• It is separated into two sections anatomically:

> Neurohypophysis – posterior pituitary. 

> Adenohypophysis – anterior pituitary.

PITUITARY PATHOLOGIES

• Acromegaly: Disorder caused by excess GH, also known as gigantism. There may also be growth hormone deficiency. These conditions affect the body, both physically and cognitively.

• Diabetes insipidus: Caused by reduced production of vasopressin. if characterized by a large increase in the production of urine, which causes thirst, and consequently increase in water intake.

• Hypopituitarism: Endocrine disease characterized by reduced production of one or more pituitary hormones. When there is a reduction in most hormones, this condition is given the term panhypopituitarism. Consequently, the reduction of one or more pituitary hormones will influence the functioning of other glands in the body.

3.EPITHALAMUS

• Structure posterior to the diencephalon, being a central segment of the brain. He has as one of its main structures the pineal gland.

• It is an important communication path between the limbic system, base nuclei and other areas of the brain.

• Thanks to the retina and impulses arriving through the suprachiasmatic nucleus it becomes possible, through light, the production of melatonin. this hormone secreted by the pineal gland is directly responsible for our cycle of sleep/wake.

• Because of this, dark or low light environments stimulate the production of melatonin. While environments with plenty of light inhibit its production.

4.SUBTHALAMUS

• It is a structure that is not easily observable. Being located in the area transition between the diencephalon and the midbrain.

• The subthalamic nucleus plays an important role among the circuits of the cortex cerebral cortex and the basal nuclei, these being fundamental for the regulation of motricity.

• Lesions in this region are responsible for a syndrome known as hemiballismus, which consists of involuntary movements of the extremities of the body. In Parkinson's disease it is one of the pathways affected.

III VENTRICLE

It is a unique cavity in the diencephalon that communicates with the IV ventricle through the cerebral aqueduct and with the lateral ventricles through the respective interventricular foramina.

Third Ventricle When the brain is sectioned in the midsagittal plane, the lateral walls of the third ventricle are exposed widely; the existence of a depression, the hypothalamic sulcus, is then verified, which extends from the cerebral aqueduct to the interventricular foramen.The thalamus is responsible for the portions of the wall above this groove, while the hypothalamus is responsible for the parts of the wall below.

On the floor of the III ventricle, from anterior to posterior, the following formations are found: optic chiasm, infundibulum, cinereous tubercle and mammillary bodies, belonging to the hypothalamus. intethalamia, which appears only sectioned.

Hypothalamus is a region of the brain located below the thalamus and which acts in the regulation of body temperature, hunger, thirst and sexual behavior.

Hypothalamus is a region of the brain located just below the thalamus. It is a small region, but with great importance for the proper functioning of the organism, being considered the integrating link between the endocrine and nervous systems. The hypothalamus regulates thirst, appetite, temperature and blood pressure. 

It is also responsible for producing hormones that stimulate and inhibit the action of the pituitary gland, acting, therefore, indirectly, on different structures of our body. The hypothalamus also produces hormones that are released by the neurohypophysis, antidiuretic hormone and oxytocin. The antidiuretic hormone ensures greater reabsorption of water by the kidneys, while oxytocin is related to the ejection of milk by the mammary glands and uterine contraction.

Summary about Hypothalamus 

• It is a small structure of the brain. 

• It performs a number of important functions in the body, such as regulating hunger, temperature and blood pressure. 

• It produces hormones that will be secreted by the neurohypophysis and inhibition and release hormones that will act by controlling the secretion of hormones by the pituitary. 

• Antidiuretic hormone and oxytocin are the hormones made by the hypothalamus and released by the neurohypophysis. 

• The antidiuretic hormone promotes an increase in the concentration of urine, as it ensures greater reabsorption of water by the kidneys. 

• Oxytocin promotes contraction of the uterus at the time of childbirth and promotes milk ejection.

Functions of the Hypothalamus 

The hypothalamus is a region of the brain that has a number of important functions, being considered the integrating link between the endocrine system and the nervous system. Among the functions that can be attributed to the hypothalamus, we can highlight: 

• cardiovascular regulation (increase and decrease in blood pressure and increase and decrease in heart rate); 

• regulation of appetite and energy expenditure; 

• regulation of body water (controls the excretion of water in the urine and provides a feeling of thirst); 

• body temperature regulation; 

• acts on the biological clock; 

• regulates milk ejection and uterine contraction at the time of childbirth; 

• plays a role in sexual and mating behavior; 

• initiates fight-or-flight response; 

• stimulates and inhibits the secretion of hormones by the pituitary gland.

Hormone Productions  

The hypothalamus is a brain structure that produces hormones that act to control pituitary secretion and hormones that are released by the pituitary. Initially, we will talk about the hormones synthesized by the hypothalamus and which control the action of the pituitary gland. These hormones are known as hypothalamic releasing and inhibitory hormones and are synthesized by special neurons in the hypothalamus. They are:

• Thyrotropin-releasing hormone (TRH): acts by stimulating the secretion of thyroid-stimulating hormone (TSH) and prolactin. 

• Corticotropin Releasing Hormone (CRH): Promotes the release of adrenocorticotropic hormone (ACTH). 

• Growth Hormone Releasing Hormone (GHRH): It works by ensuring the release of growth hormone. 

• Growth hormone inhibitory hormone (GHIH) (somatostatin): causes inhibition of growth hormone release. 

• Gonadotropin-releasing hormone (GnRH): triggers the release of luteinizing hormone (LH) and follicle-stimulating hormone (FSH). 

• Dopamine or prolactin inhibitory factor (PIF): acts by inhibiting the release of prolactin.

In addition to the releasing and inhibitory hormones, the hypothalamus produces: the antidiuretic hormone or vasopressin and oxytocin. Despite being synthesized by the hypothalamus, the two hormones will be released by the pituitary, more precisely by the neurohypophysis. Both hormones are polypeptides that contain nine amino acids. See, below, the functions that can be attributed to these two hormones. 

• Antidiuretic hormone (ADH) or vasopressin: it is responsible for decreasing the volume of urine and increasing its concentration. This happens because this hormone promotes an increase in the permeability of the tubules and collecting ducts, causing a greater amount of water to be reabsorbed. 

• Oxytocin: acts in the contraction of the uterus at the time of childbirth, in addition, it promotes the ejection of milk by the mammary glands, a process that is stimulated by the baby's suction.

Hypothalamus and Pituitary 

The hypothalamus is directly connected to the hypophysis (also called the pituitary) from a stalk called the infundibulum. The communication between these two regions is called the hypothalamic-pituitary axis, whereby the hypothalamus establishes control of the pituitary gland and the latter, in turn, establishes control of other glands in the body through the production of hormones. 

The pituitary is divided into two regions, the neurohypophysis and the adenohypophysis, which are anatomically united, but synthesize different hormones. Hormones secreted by the neurohypophysis (or posterior pituitary) are synthesized in the hypothalamus region and then transported to the neurohypophysis region. 

This region secretes the antidiuretic hormone (ADH), responsible for increasing the reabsorption of water by the kidneys, participating in the control of blood pressure, and also the hormone called oxytocin, which stimulates the ejection of milk in the mammary glands and uterine contractions during childbirth.

The adenohypophysis (or anterior pituitary), unlike the neurohypophysis, produces its own hormones, in addition to storing and secreting them into the bloodstream. Among the hormones produced in the anterior pituitary are: 

• Adrenocorticotropic hormone (ACTH): stimulates cells in the adrenal cortex to synthesize their corticoid hormones. 

• Thyroid-stimulating hormone (TSH): stimulates the thyroid to produce its T3 and T4 hormones. 

• Follicle stimulating hormones (FSH) and luteinizing hormones (LH): act on the gonads to produce sex steroid hormones. 

• Growth hormone (GH) or somatotropin: acts on various tissues, such as bones, stimulating their growth. 

• Prolactin (PRL): acts on the mammary gland, stimulating milk production. The secretion of anterior pituitary hormones is controlled by the hypothalamus, through hypothalamic hormones.

Diseases related to the Hypothalamus 

The hypothalamus is related to the regulation of several activities, and any disorder that compromises the proper functioning of this region can affect the functioning of the activities that are regulated by it. 

Among some diseases related to the hypothalamus, there is acromegaly, which can be developed by a dysfunction in the functioning of the hypothalamus and which is triggered when levels of growth hormone (GH) are above normal. 

Another related condition is gonadotropin deficiency, which can lead to low levels of follicle-stimulating hormone (FSH) and luteinizing hormone (LH), which in turn will affect the production of sex steroid hormones. Furthermore, there is the occurrence of pituitary tumors, which trigger changes in the production of several hormones.

THALAMUS

About 3 cm long and making up 80% of the diencephalon, the thalamus is made up of two paired, ovulated masses of grey matter that are arranged into nuclei and contain tracts of white matter. 

Usually, a gray matter connection called the mass intermedia (interthalamic adhesion) joins the right and left parts of the thalamus. 

The anterior end of each thalamus presents an eminence, the anterior tubercle of the thalamus, which participates in the delimitation of the interventricular foramen. 

The pulvinar, a sizable eminence that projects over the lateral and medial geniculate bodies, is present on the posterior end, which is significantly larger than the anterior. 

The medial geniculate body is part of the auditory pathway, and the lateral part of the optic pathway, and both are considered by some authors as a division of the diencephalon called the metathalamus.

The lateral portion of the upper surface of the thalamus forms part of the floor of the lateral ventricle and is lined by ependymal epithelium (the epithelium that lines this part of the thalamus and is called the fixed lamina). The medial portion of the thalamus forms the lateral wall of the III ventricle, whose roof is constituted by the fornix and the corpus callosum, telencephalic formations. The transverse fissure is occupied by a cul-de-sac of the pia mater, which then enters the fabric of the choroid.The internal capsule, a small bundle of fibres linking the cerebral cortex to subcortical nerve centres, separates the lateral surface of the thalamus from the telencephalon. The hypothalamus and subthalamus continue down the inferior surface of the thalamus. 

Structural Parts

The thalamus is located in a central region of the brain called the diencephalon, and this position allows it to act by transmitting and integrating various motor and sensory impulses between the central nervous system and the periphery.

Parts 

• Anterior, medial, and lateral parts, separated by the internal medullary lamina. 

• Interthalamic adhesion, connecting the thalamus on each side. 

• Medial and lateral geniculate bodies. 

Relations 

• Anteriorly: interventricular foramen of Monro and internal cerebral vein 

• Medially: third ventricle 

• Posteriorly: stria terminalis, the third ventricle's choroid plexus, the body of the fornix, the internal cerebral vein, the thalamostriate vein, the caudate nucleus, the internal capsule, the quadrigeminal bodies, and the corpus callosum are all located posteriorly. 

• Inferiorly: hypothalamus, mesencephalic aqueduct, mesencephalic tegmentum

Cores 

1. Anterior group: anterior nuclei 

2. Posterior group: 

Posterior subgroup (pulvinar, medial geniculate body, lateral geniculate body) 

Dorsal subgroup (dorsal lateral nucleus and posterior lateral nucleus) 

Ventral subgroup (anterior ventral nucleus, lateral ventral nucleus, lateral ventral posterior nucleus, medial ventral posterior nucleus) 

3. Medial group: intralaminar nuclei, dorsomedial nucleus 

4. Reticular nucleus 

5. Median group

Some nuclei transmit impulses to the sensory areas of the brain: 

• Body (nucleus) Medial Geniculate – transmits auditory impulses; 

• Body (nucleus) Lateral Geniculate – transmits visual impulses; 

• Body (core) Ventral Posterior – transmits impulses for taste and for somatic sensations, such as touch, pressure, vibration, heat, cold and pain.

The thalamus serves as a way station for most of the fibers that travel from the lower part of the brain and spinal cord to the sensory areas of the brain. The thalamus sorts the information, giving us an idea of ​​the sensation we are experiencing, and directs it to specific areas of the brain for more accurate interpretation.

FUNCTIONS OF THE THALAMUS: 

• Sensitivity; 

• Motricity; 

• Emotional Behavior; 

• Cortex activation; 

• It plays some role in the wakefulness mechanism, or state of alertness.

The human brain is an organ that weighs 1.3 kg and remains largely an enigma. However, most people are aware of the grey matter in the brain, which is important for cognitive processes including memory, thinking, and learning.

The mass or gray matter designates, more specifically, regions scattered throughout the brain in which nerve cells, known as neurons, are concentrated. The cerebral cortex, a thin layer of grey matter on the surface of the brain, is the area thought to be most crucial for cognition. 

But the other half of the brain - the white matter - is often overlooked. The white matter lies below the cortex and in deeper regions of the brain. Where it is present, it connects gray matter neurons to each other.

WHITE MATTER

This lack of recognition, in large part, comes from the difficulty of studying the mass or white matter.

Because it is located beneath the surface of the brain, even the highest imaging technology cannot easily reveal its details. But recent discoveries, made possible by advances in brain imaging and autopsy examinations, are beginning to show researchers the importance of white matter. 

Axons, which resemble lengthy wires and conduct electrical information, make up the many billions of cells that make up white matter. Consider axons as the extended tails that function as the neurons' extensions.

Synapses are junctions where axons join neurons together. The exchange of information between neurons occurs here. 

Axons gather in bundles or branches, which extend throughout the brain. If they were aligned, their total length in a single human brain would be about 136 thousand kilometers. 

Many axons are insulated with myelin, a layer composed mainly of fat that speeds up to 100 times the electrical signaling, or communication, between neurons. This increased speed is fundamental to all brain function and is one of the reasons for the unique mental abilities of Homo sapiens. 

While there is no doubt that our large brains are a consequence of the addition of neurons that occurred during evolution, the increase in white matter in the evolutionary process was even greater.

This little-known fact has profound consequences. The increase in the volume of white matter - mainly the myelin sheaths that cover axons - enhances the efficiency of gray matter neurons to optimize brain functions. 

Imagine a country where all cities function independently but are not connected by roads, wires, internet or other connections. This would be a similar scenario to the brain without the white matter. 

Higher functions, such as language and memory, are organized into networks in which regions of gray matter are connected by branches of white matter. The more extensive and efficient these connections are, the better the brain functions.

Importance of White Matter

The central nervous system's white matter is in charge of information transmission. The name it receives derives from the color that the myelin sheaths, which are white in color, give this substance. Myelin makes electrical information travel quickly from one neuron to another, coating its axons. 

In the brain, the white matter is located underneath the gray matter, which is the cerebral cortex. In the spinal cord, it is found on the outside, covering the gray matter. It is made up of axons that send sensory and motor information to the corresponding place. Although, initially, it was attributed the function of disseminating information, it also seems to be involved in other processes.

White Matter and Alzheimer's 

Considering its essential role in connections between brain cells, white matter lesions can impair any aspect of cognitive or emotional function. 

Numerous brain illnesses involve white matter dysfunction, which can be severe enough to lead to dementia. These illnesses frequently involve myelin destruction, and when the illness or injury is more serious, axons can also sustain damage. 

My coworkers and I coined the term "white matter dementia" to describe this illness more than 30 years ago. In this condition, the dysfunctional white matter is no longer functioning properly as a connection, which means that the gray matter is not able to act continuously and synchronously. Essentially, the brain has disconnected from itself.

Equally important is the possibility that white matter disorders influence many diseases that are currently believed to have gray matter origin. 

Some of these diseases insist on defying our understanding. I suspect, for example, that white matter lesions may be critical in traumatic brain injuries and in the early stages of Alzheimer's disease. 

Alzheimer's is the most common type of dementia in elderly individuals. It can impair cognitive functions and steal people's very identity. And there is no cure or effective treatment for it. 

Ever since Alois Alzheimer observed gray matter proteins - known as amyloid and tau - in 1907, neuroscientists have believed that the accumulation of these proteins is the core problem behind Alzheimer's disease. Even so, many drugs that eliminate these proteins do not stop patients' cognitive decline.

Recent discoveries increasingly indicate that white matter lesions prior to the accumulation of these proteins may be the true cause of the disease. As the brain ages, it often experiences a gradual loss of blood flow, caused by narrowing of the vessels that carry blood from the heart. And the lower blood flow has a strong impact on the white matter. 

It is important to note that there is increasing evidence that inherited forms of Alzheimer's also have early white matter abnormalities. This suggests that preserving blood flow to the white matter through therapies may be more successful than trying to get rid of the proteins. 

A simple treatment that may help is controlling high blood pressure, which can reduce the severity of white matter abnormalities.

White Matter and Traumatic Brain Injuries 

Patients with traumatic brain injuries (TBIs), particularly moderate and severe injuries, can be disabled for life. 

One of the most dangerous consequences of these injuries is chronic traumatic encephalopathy, a brain disease believed to cause progressive and irreversible dementia. 

In patients with TCL, accumulation of tau protein in the gray matter is evident. 

White matter lesions are frequently discovered in TBI survivors, according to researchers who have known this for a long time. Observations of the brains of people with repetitive TCLs - such as football players and military veterans, who have been studied frequently - have shown that damage to the white matter is evident and may precede the appearance of protein tangles in the gray matter. 

There is growing enthusiasm among scientists about the recent interest in white matter. Researchers are beginning to recognize that the traditional focus on studying gray matter has not yielded the expected results.

Learning more about the half of the brain known as the white matter could help us find the answers needed to ease the suffering of millions of people in the coming years.

GRAY MATTER 

 It is referred to as grey matter or grey matter to the component that makes up specific regions of the central nervous system (brain and spinal cord) that have a distinctive grey colour and are made up of glial cells, also known as neuroglia, as well as neuronal bodies (the "body" of neurons) and dendrites without myelin. 

The gray matter is found inside the spinal cord, tending towards the center and to the sides, in the shape of the letter H; and in the brain, on the other hand, in the external zone except in the basal ganglia, thus forming the cerebral cortex: the most complex nervous structure in the human body. 

In principle, as it is not covered with myelin, gray matter is not used for the rapid transmission of nerve impulses , which is why it is associated with other intellectual capacities of human beings , although it is not possible to state that a greater mass. of gray matter is to have greater intelligence, just as dolphins have more than human beings.

Gray Matter's Function

The brain's gray matter fulfills the vital function of being a receiver of information and in charge of thinking, that is, reasoning and memory in its various areas and meanings. From linguistic ability, perception, interpretation, abstraction and a huge etc. of mental and cognitive functions, they all depend on gray matter and the connections between its various types of neurons. 

On the other hand, in the spine, the gray matter acts as a regulator and selector of the information that will be transmitted to the brain , but also as a source of immediate impulses and the so-called “body memory” that allows all reactions not to have to come from the brain, which makes the work of nervous processing lighter.

Location of Gray Matter 

Gray matter is found all over the surface of the brain, as it forms the cerebral cortex, the most developed, complex and most connected area of ​​our entire nervous system. It is also found in the basal ganglia, deep in the cerebellum, and in the thalamus and hypothalamus areas. 

In turn, it can be found inside the spinal cord, in an H-shaped or butterfly-shaped segment, in the dorsal, intermediolateral and ventral horns of the vertebral column, as well as in the intermediate zone (dorsal nucleus of Clarke).

Importance of Gray Matter

Medical cases of people injured in regions of the brain rich in gray matter have been looked at, and the impact that such injuries can and often do have on several areas of human cognitive functioning has been observed: language ability, short-term or long-term memory. , associative capacity, learning , etc. 

As a result, it is now known that grey matter is the specific area of the nervous system that allows for the development of sophisticated, imaginative, and abstract thought in early humans. Therefore, not enough to have a larger brain volume to possess human intelligence, but it required a brain with an abundance of gray matter and a rough shell, which fosters countless connections between the neurons that compose it.

Gray Matter and White Matter 

Gray matter differs from white matter in much more than its color, determined by the high presence of myelin-bearing dendrites in the latter (myelin is whitish in color). They are distinguished in the speed of transmission of nerve information, much faster in the white matter than in the gray, and in the depth to which it is found, since the white matter is the interior of the brain (aunque the cover of the brain). spinal cord). 

For a long time it was thought that the white matter was passive, but today we know that it plays a vital role in the distribution of nerve information and in the modulation of action potentials, that is, it is responsible for the basic operational functions that it supports. complex processing, which is handled by gray matter, especially in the brain.

Difference between the Gray Matter and the White Matter of the brain

Chances are, you've come across terms like brain gray matter and white matter somewhere—like a study or a news article. However, the difference between the two is not always clear. After all, what are they for? What are the main features? 

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Basically, the gray matter and the white matter of the brain make up the central nervous system, which acts directly in perception, in the functioning of the body and in the performance of essential activities, such as locomotion, reasoning and memory.

The human nervous system, as a product of its phylogenetic evolution, is a very sophisticated system that has allowed, and still allows, us to relate, adapt to the environment and our survival. Several important functions depend on it, such as breathing, physiological activation when danger appears, cognitive functions (such as attention or memory), among others. 

The complexity of this system makes it still a great unknown for science. The nervous system has been the subject of study over the years and, although there are still many questions to be answered about it, we have a certain amount of knowledge about its functioning and structure.