What is Human Brain? Brain Anatomy: Functions and Structures
What is Human Brain?
The human brain is the major organ of the human nervous system, and it is joined by the spinal cord to form the central nervous system. The cerebrum, brainstem, and Cerebellum make up the brain. Most of the body's functions are controlled by it, which processes, integrates, and coordinates the information received from the sense organs and makes decisions about the instructions delivered to the rest of the body.
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Brain Anatomy: Functions and Structures
Cerebrum (brain)
The cerebrum is the brain's largest and most complicated structure. It is split into two halves, each with four lobes: frontal, parietal, temporal, and occipital. Higher cognitive functions such as language, reasoning, memory, learning, emotion, and personality are all controlled by the cerebrum. The cerebrum also houses primary sensory and Motor regions, which process and govern sensory and motor input from many parts of the body.The cerebrums' two hemispheres are linked by the corpus callosum, a thick band of nerve fibres that facilitates communication between them. The cerebral cortex is the cerebrum's outer layer, which is made up of grey matter (neuron cell bodies). White matter (myelinated axons) is the inner layer that transports signals between different sections of the cortex and other portions of the brain.
Cerebellum
The cerebellum is a region of the brain that is involved in movement and balance coordination. It also helps with cognitive skills, including language and attention. The cerebellum is placed behind the brain stem, beneath the cerebrum. It is divided into three lobes by deep grooves. The cerebellum contains many nerve cells in a thin layer of tissue called the cerebellar cortex. The cerebellar cortex communicates with the cerebellar nuclei, which are located deep within the cerebellum. The cerebellar nuclei are responsible for transmitting information from the cerebellum to other regions of the nervous system.The cerebellum accepts input from sensory systems and other brain regions and uses it to fine-tune motor action. The cerebellum does not initiate movement, but it does help with coordination, precision, and timing. The cerebellum, for example, assists you in walking smoothly, writing neatly, and speaking correctly. Motor learning, or the process of learning and fine-tuning motions, is also influenced by the cerebellum. The cerebellum, for example, assists you in learning to ride a bike, play an instrument, or type on a keyboard. As a teaching signal, the cerebellum employs a type of input known as the climbing fibre, which causes changes in the intensity of other inputs known as parallel fibres. These alterations are related to synaptic plasticity, or synapses' ability to change strength over time.
Cerebellar damage can lead to problems with fine movement, balance, posture, and motor learning. These conditions are referred to as ataxia, which means "lack of order or coordination." Depending on whether a portion of the cerebellum is affected, ataxia can affect different parts of the body. Injury to the archicerebellum, for example, can result in problems with balance and eye movements; injury to the vermis can result in problems with stance and gait; and damage to the lateral hemispheres can result in problems with limb movement and speech. Strokes, brain bleeds, poisons, genetic defects, infection, cancer, and alcohol misuse are all common causes of cerebellar injury.
The brainstem
The brainstem connects the brain to the spinal cord at the base of the brain. It is divided into three sections: the midbrain, the pons, and the medulla oblongata. The brainstem controls critical functions such as breathing, heart rate, blood pressure, digestion, and sleep. It also regulates reflexes and involuntary motions, including swallowing, coughing, and sneezing.In addition, the brainstem acts as a relay station for sensory and motor information between the spinal cord and other areas of the brain. It contains many cranial nerves that innervate various head and neck structures, such as the eyes, ears, nose, mouth, and throat.
Midbrain
The midbrain is located at the apex of the brainstem. The cerebral aqueduct, which connects the third and fourth ventricles (cavities filled with cerebrospinal fluid), runs across it. The quadrigeminal plate (also known as the tectal plate) is located in the midbrain and consists of four rounded elevations: two superior colliculi and two inferior colliculi. The superior colliculi are engaged in visual reflexes such as object tracking and eye movement coordination. The inferior colliculi are engaged in auditory responses such as sound orientation and localization.The cerebral peduncles, which are two huge bundles of nerve fibres that connect the cerebrum to the brainstem and spinal cord, are also found in the midbrain. The crura cerebri and tegmentum are the two sections of the cerebral peduncles. The corticospinal tracts, which convey motor signals from the motor cortex to the spinal cord, are found in the crura cerebri. Various nuclei and routes in the tegmentum are involved in sensory processing, arousal, pain modulation, and movement control.
Pons
The pons is the brainstems' central section. It is situated anterior to the cerebellum and posterior to the clivus (a bony inclination at the base of the skull). The pons is divided into two sections: the basilar part and the pontine tegmentum.The basilar part is a prominent bulge on the pons's anterior side that houses the basilar artery, which provides blood to the brainstem and cerebellum. Several structures related to motor control are also found in the basilar section, including:
- The corticospinal tract is a branch of the crura cerebri that transports motor signals from the motor cortex to the spinal cord.
- Axons that begin in the motor cortex and terminate in various cranial nerve nuclei in the brainstem are referred to as corticonuclear fibres.
- Pontine nuclei: neuronal clusters that receive input from the cerebral cortex and transfer it to the cerebellum through the middle cerebellar peduncles.
- The pontine tegmentum is a dorsal area of the pons that contains a number of structures involved in sensory processing, autonomic regulation, and sleep-wake cycles, including:
- A network of neurons that stretches throughout the brainstem and regulates arousal, attention, and muscular tone is known as the pontine reticular formation.
- Cranial nerve nuclei: neuronal groups that give rise to or receive input from the four cranial nerves: trigeminal (V), abducens (VI), facial (VII), and vestibulocochlear (VIII). These nerves control facial feelings and motions, as well as the eyes, ears, and balancing organs.
- Ascending spinal tracts: groups of nerve fibres that transport sensory information from the spinal cord to higher brain centres
- Two tiny nuclei that create norepinephrine (a neurotransmitter) and regulate alertness, mood, memory, and stress reactions.
