Anatomy of the brain

BrainOverview of the brain anatomy. Major divisions of the brain. Brainstem. Ventricles
~ 8 min

In this note, we are going to discuss the anatomy of the brain and its general functions.

Divisions

The brain consists of four major divisions:

Cerebral hemispheres (or cerebrum)

Diencephalon

Cerebellum

Brainstem

The brainstem itself is further divided into three parts:

Midbrain

Pons Varolii

Medulla oblongata

Each of these components plays a critical role in integrating sensory and motor information, maintaining vital body functions, and providing complex cognitive processes.

Cerebral hemispheres

Let’s start with the cerebral hemispheres, there are two of them: the left and the right. The surface of the hemispheres is uneven. It consists of numerous elevations known as gyri

and depressions known as sulci.

Major sulci divide the hemispheres into lobes:

Frontal lobe (lobus frontalis)

Temporal lobe (lobus temporalis)

Parietal lobe (lobus parietalis)

Occipital lobe (lobus occipitalis)

Additionally, there’s the insular lobe (or simply insula), which is kind of hidden deep into the brain.

The frontal lobe is responsible for controlling skeletal muscles, i.e., our movements, as well as for complex functions such as decision-making, motor planning, and determining what is good and what is bad.

Simply put, it defines us as humans in general and as individuals in particular.

The temporal lobe contains auditory, gustatory, speech, and memory centers. The parietal lobe receives and processes sensory information, such as the sense of touch, pain, vibration, etc.

The occipital lobe is predominantly responsible for vision.

The insular lobe participates in a bit of everything: from speech formation to the control of the heartbeat and other vital functions.

The cerebral hemispheres consist of gray and white matter, just like any other part of the central nervous system. Gray matter consists of neuronal cell bodies that generate nerve impulses,

while white matter comprises neuron processes that transmit nerve impulses, thereby providing communication between different parts of the nervous system.

Gray matter is represented by the cerebral cortex, located on the surface, and the subcortical nuclei, or so-called basal ganglia, which are situated slightly deeper.

White matter is grouped into thick bundles of nerve fibers that ascend and descend to various parts of the nervous system, performing a communicating function.

Diencephalon

The diencephalon consists of three parts:

epithalamus

thalamus

hypothalamus

The most important part of the epithalamus is the pineal body (or pineal gland), essentially an endocrine gland producing the hormone melatonin,

which participates in regulating sleep-wake cycles and is sometimes referred to as the sleep hormone.

The thalamus is an egg-shaped structure consisting of numerous nuclei.

A huge number of neural pathways pass through the thalamus, with its nuclei acting as switches in these pathways.

They allow some signals to pass to the cerebral cortex, while other signals are blocked or slightly slowed down. In general, the thalamus serves as a sort of “bouncer” in the brain.

The hypothalamus, like the thalamus, is essentially a collection of nuclei. It plays a role in maintaining homeostasis, i.e., the constancy of the internal environment, thereby controlling such areas as water balance, thermoregulation, sleep-wake cycles, sexual behavior, and so on.

Moreover, the hypothalamus is directly connected to the pituitary gland, the most crucial endocrine gland in our body, and significantly influences the production of its hormones.

Brainstem

The brainstem, as mentioned before, consists of three major divisions:

Midbrain

Pons Varolii

Medulla oblongata

In general, it controls vital, life-sustaining functions such as breathing, heart rate, vascular resistance, and partially digestion, among others.

Moreover, numerous cranial nerve nuclei are located within the brainstem. And the cranial nerves emerge from the brain at various levels.

Cerebellum

And the last division is the cerebellum, which literally means “little brain”.

The function of the cerebellum is to coordinate our movements, maintain balance and proper posture.

Brain meninges

Since the brain is the most important structure in our body, it must be well-protected against various kinds of damage. In this regard, the cranium alone is not sufficient; so the brain is additionally covered by three meninges: