Have you ever wondered what is inside your brain? There are so many regions and sections it's a surprise they can all fit. This glossary will help you understand which parts actually matter in all that gray matter.
The Brain as a Whole
There are several parts of the brain that are vital to its functionality and makeup. They include the following terms.
In biology, a nucleus (plural: nuclei) is an organelle that contains the genetic material of a cell and controls cellular activities.
A nucleus typically refers to a group of nerve cells (neurons) that are in a specific region of the brain and work together to perform a particular function. We can find these nuclei in various subcortical structures, such as the thalamus and the basal ganglia, as well as in the brainstem.
The Basal Ganglia
Pronunciation: bas-al gan-gli-a
Basal Definition: arising from the base of a stem.
Ganglia Definition: a mass of nerve tissue containing cell bodies of neurons external to the brain or spinal cord.
The basal ganglia is a group of interconnected nuclei located deep within the brain that are involved in a variety of functions related to movement control, reward, and learning.
It is like a command center for your movements, helping you to start, stop, and adjust your movements based on the situation. It also plays a role in helping you learn and remember certain movements, and in processing the rewards associated with certain behaviors.
Some of the specific nuclei within the basal ganglia include the caudate nucleus, putamen, and globus pallidus.
A hormone is a chemical messenger that is produced by the glands of the endocrine system and released into the bloodstream. It travels to various target organs and tissues throughout the body.
Hormones help to regulate a wide range of physiological processes, including growth and development, metabolism, reproduction, and the body's response to stress. They play a vital role in maintaining the balance and stability of the body's internal environment.
Hormones are influenced by various factors, such as stress, diet, and exercise, and affected by certain medical conditions and medications.
A membrane is a thin, flexible layer of material that separates or surrounds two different areas or substances.
Membranes are found in many different parts of the body and serve a variety of functions, from protecting internal organs to controlling the movement of substances into and out of cells.
The ventricles are fluid-filled spaces in the brain that are connected to each other and to the central canal of the spinal cord.
There are four ventricles in the brain. These spaces are lined with a thin layer of cells called ependymal cells, which produce cerebrospinal fluid (CSF). The ventricles help circulate CSF throughout the brain and spinal cord, and also play a role in removing waste products and maintaining a stable chemical environment in the brain.
Pronunciation: me-nix me-ne-gines
The meninges (or the meninx) are a set of three layers of protective tissue that surround the brain and spinal cord. They act as a cushion to protect the delicate nervous tissue from physical trauma and help to contain the cerebrospinal fluid that nourishes and supports the brain and spinal cord.
The three layers of the meninges are:
- the dura mater
- the arachnoid mater
- and the pia mater
The meninges play an important role in protecting the brain and spinal cord from injury, infection, and other types of damage. They also help to regulate the pressure and flow of cerebrospinal fluid, which is essential for maintaining proper brain function.
Pronunciation: sub-cor-ti-cal struc-ture
Subcortical Definition: of, relating to, involving, or being a part of the brain below the cerebral cortex.
The subcortical structures refer to those parts that are beneath the outer layer. These structures include the thalamus, hypothalamus, basal ganglia, brainstem, and the limbic system.
They play important roles in various functions such as movement, sensation, emotion, memory, and motivation.
There are 3 main parts of the brain. One of them is the forebrain.
The forebrain is the largest part of the brain. The forebrain controls our reproductive functions, body temperature, emotions, hunger, and sleep. It includes the:
The cerebrum is the largest part of the brain, and it is responsible for most of our conscious thoughts, feelings, and behaviors.
It is the most complex and versatile part of the brain too, and it is what makes us uniquely human. It’s constantly processing information from our senses and from other parts of the brain, and using that information to help us interact with the world around us.
It is divided into two hemispheres: the left and the right
Pronunciation: ce-re-bral hemi-sphere
Hemisphere Definition: half of a spherical or roughly spherical body.
A cerebral hemisphere is one of the two halves of the cerebrum. The cerebral hemispheres are located in the upper part of the skull and are separated by a deep groove called the longitudinal fissure.
Each cerebral hemisphere controls the opposite side of the body, and each is responsible for many of our conscious thoughts, feelings, and behaviors.
The left hemisphere is typically more involved in logical and analytical thinking, language, and math, while the right hemisphere is more involved in creativity, spatial awareness, and emotional processing.
They are critical parts of the brain that allow us to interact with the world around us, process information, and make sense of our experiences.
Pronunciation: cor-pus cal-lo-sum
Corpus Definition: the main part or body of a bodily structure or organ.
The corpus callosum is a thick band of nerve fibers that connects the two hemispheres of the brain.
It allows the left and right hemispheres to communicate with each other, so that they can work together to process information and carry out complex tasks.
Without this connection between the two hemispheres, our ability to process information and make sense of our experiences would be greatly reduced.
The hypothalamus is a small but important structure in the brain that plays a vital role in regulating many of the body's essential functions, such as hunger and thirst, body temperature, sleep, and emotional responses.
It acts as a control center that receives and processes information from other parts of the brain and nervous system and helps to maintain homeostasis, or the balance of bodily functions.
The hypothalamus also plays a key role in the endocrine system, regulating the release of hormones that control many bodily processes.
The thalamus is a structure in the brain that acts as a relay station for sensory information. It receives signals from sensory organs such as the eyes, ears, skin, and mouth, and then sends that information to the appropriate areas of the cerebral cortex, which is the outer layer of the brain responsible for processing and interpreting sensory information.
The thalamus also plays a role in controlling motor functions, sleep, and consciousness.
Another main part of the brain is the midbrain (also known as the mesencephalon).
The midbrain is in the center of the brain and is technically part of the brainstem. It is responsible for a variety of functions including eye and body movements, processing auditory and visual information, and regulating sleep and waking cycles.
The midbrain plays a critical role in regulating functions like movement, vision, and hearing too.
It includes the:
- Red nucleus
- Cerebral peduncles
The tectum is a part of the midbrain that is located at the back of the brainstem, just above the pons.
It is made up of two pairs of small bumps, called the superior colliculus and inferior colliculus, which are involved in processing visual and auditory information.
The colliculi, also known as the corpora quadrigemina, are two pairs of small bumps located in the midbrain, specifically in the tectum region.
They are made up of the superior colliculus and the inferior colliculus.
- The superior colliculus is responsible for processing visual information and helping to control eye movements. It receives input from the eyes and other visual pathways.
- The inferior colliculus is responsible for processing auditory information and helping to locate the source of a sound. It receives input from the ears and other auditory pathways.
The tegmentum is a part of the brainstem that is located between the substantia nigra and the cerebral aqueduct, which connects the third and fourth ventricles of the brain.
It is composed of various structures, including the reticular formation, red nucleus, and periaqueductal gray.
The tegmentum plays an important role in regulating many different functions of the body, including movement, sensation, sleep, arousal, and autonomic functions like heart rate and blood pressure. For example, the reticular formation within the tegmentum is involved in regulating levels of consciousness and arousal.
Pronunciation: red nu-cle-us
The red nucleus is a structure located in the midbrain, specifically within the tegmentum region. It appears reddish due to the high concentration of iron in its cells.
The red nucleus plays an important role in controlling voluntary movement of the arms and legs. It receives input from the cerebral cortex and sends signals down to the spinal cord to coordinate movement.
Additionally, it is involved in the production of a neurotransmitter called dopamine, which is important for controlling movement and is the primary neurotransmitter affected in Parkinson's disease.
Pronunciation: ce-re-bral pe-dun-cle
Peduncle Definition: a narrow part by which some larger part or the whole body of an organism is attached.
The cerebral peduncles are structures located in the midbrain. They are a pair of large bundles of nerve fibers that connect the cerebral cortex, the outer layer of the brain responsible for many important functions, to the rest of the brain.
The cerebral peduncles contain a variety of nerve fibers, including motor fibers that are involved in controlling movement and sensory fibers that are involved in processing sensory information. They also contain fibers that are involved in various other functions, including vision, hearing, and attention.
The last main part of the brain is the hindbrain.
The hindbrain is at the bottom of the brain near the base of the skull. It monitors functions like breathing, heartbeat, sleep, and motor learning.
It includes the:
- Medulla Oblongata
- The Pons
The cerebellum is a part of the brain located at the base of the skull. It can be described as a small, cauliflower-shaped structure that is responsible for coordinating and regulating movements, posture, and balance.
The cerebellum receives information from the sensory systems, such as the eyes, ears, and muscles, and uses this information to help control voluntary movements. It also plays a role in maintaining posture and balance.
The cerebellum is also involved in some cognitive functions, such as attention, language, and working memory. It helps to integrate and process information from different parts of the brain to produce smooth, coordinated movements and other complex behaviors.
The vermis can be described as a thin, centrally located strip of tissue that runs along the midline of the cerebellum. The word vermis means "worm" in Latin, and the vermis is so named because of its worm-like appearance.
It is located between the two lateral lobes of the cerebellum and is involved in coordinating movements and maintaining balance in the body.
Pronunciation: me-dul-la ob-lon-ga-ta
Medulla Definition: the inner or deep part of an animal or plant structure.
The medulla oblongata is the lowermost part of the brainstem and connects the brain to the spinal cord.
The medulla oblongata contains many important centers that control various involuntary functions of the body.
For example, it regulates breathing by controlling the muscles of the diaphragm and other respiratory muscles. It also helps to control heart rate and blood pressure by regulating the activity of the heart and blood vessels. In addition, it plays a role in controlling the digestive system, including the secretion of digestive juices and the movement of food through the intestines.
The pons is a part of the brainstem located between the midbrain and the medulla oblongata. It's a bridge-like structure that connects the cerebrum (the largest part of the brain) with the cerebellum (the part of the brain that controls movement and balance) and the rest of the body.
The pons contains many important nerve fibers that carry messages between different parts of the brain and spinal cord. It also contains centers that control breathing, sleeping, and other vital functions. Additionally, the pons is involved in controlling eye and facial movements, hearing, and taste.
The brainstem connects the brain to the spinal cord. It can be described as a stalk-like structure that is responsible for regulating many of the body's basic life-sustaining functions, such as breathing, heart rate, blood pressure, and digestion.
The brainstem is located at the base of the brain and is composed of four main parts:
- Medulla Oblongata
- The Pons
- the PAG
The brainstem also plays a role in maintaining consciousness and alertness. It contains structures that are involved in arousal, attention, and other cognitive functions.
Periaqueductal Gray Matter
Periaqueductal Definition: of, relating to, or being the gray matter which surrounds the aqueduct of Sylvius.
Gray Matter Definition: neural tissue especially of the brain and spinal cord that contains nerve-cell bodies as well as nerve fibers and has a brownish-gray color.
The periaqueductal gray matter (PAG) is a part of the brainstem that surrounds the cerebral aqueduct, which connects the third and fourth ventricles of the brain.
It is a region of gray matter that is involved in the modulation of pain and the regulation of a variety of other functions in the body.
The PAG plays an important role in pain processing, as it is involved in the body's natural pain management system. When the PAG is activated, it can release natural painkillers called endorphins, which can help to reduce pain sensation.
The PAG is also involved in the regulation of emotional responses, such as fear and anxiety, and can influence autonomic functions such as heart rate and breathing.
Brain Systems and Glands
The brain has several systems that include glands which all work together to manage hormones.
The Endocrine System
Pronunciation: en-do-crine sys-tem
Endocrine Definition: producing secretions that are distributed in the body by way of the bloodstream.
The endocrine system is a network of glands that produce and release hormones, which are chemical messengers that regulate various functions in the body.
The glands of the endocrine system include:
- pineal gland
- pituitary gland
- thyroid gland
- parathyroid glands
- adrenal glands
- ovaries (in females)
- testes (in males)
The endocrine system works in conjunction with the nervous system to help regulate the body's internal environment and maintain homeostasis (or balance).
Pronunciation: en-do-crine gland
An endocrine gland is a type of gland that produces and secretes hormones directly into the bloodstream, rather than releasing them through ducts.
Some examples of endocrine glands include the:
- thyroid gland
- pituitary gland
- adrenal gland
Pronunciation: pi-ne-al gland
Pineal Definition: of, relating to, or secreted by the pineal gland.
The pineal gland is a small endocrine gland located in the center of the brain, near the middle of the two hemispheres.
It is responsible for producing the hormone melatonin, which helps regulate sleep-wake cycles and circadian rhythms. Melatonin production is influenced by light exposure; when it is dark, the pineal gland produces more melatonin, which can help promote sleep.
In addition to regulating sleep, the pineal gland is also involved in a variety of other functions, including immune system regulation, antioxidant activity, and the modulation of mood and emotions.
While the pineal gland has been the subject of much interest and speculation over the years, its exact role and significance in human health and disease is still not fully understood.
Pronunciation: pi-tu-i-tary gland
Pituitary Definition: of or relating to the pituitary gland.
The pituitary gland is a small gland located at the base of the brain, behind the bridge of the nose. It is often referred to as the "master gland" because it controls the functions of many other hormone-secreting glands in the body.
The pituitary gland produces and secretes hormones that regulate a wide range of bodily functions, including growth, reproduction, metabolism, and stress response.
It is divided into two parts:
- the anterior pituitary, which produces and releases several hormones
- the posterior pituitary, which stores and releases two hormones produced by the hypothalamus
Pronunciation: lim-bic sys-tem
Limbic Definition: of, relating to, or being the limbic system of the brain.
System Definition: a regularly interacting or interdependent group of items forming a unified whole.
The limbic system is a group of interconnected structures in the brain that is responsible for a variety of functions related to emotion, behavior, and motivation.
It includes the amygdala, hippocampus, hypothalamus, thalamus, basal ganglia, and parts of the cerebral cortex.
The limbic system is involved in many aspects of human behavior, including memory, motivation, pleasure, and pain. It is also involved in the regulation of the body's internal environment, such as hunger, thirst, and body temperature, as well as the regulation of the autonomic nervous system, which controls heart rate and breathing.
The limbic system plays a key role in emotional and social processing, and is thought to be involved in many psychiatric disorders.
There are several different types of tracts in the brain. They connect the nerves to the brain.
Pronunciation: cor-ti-co-spi-nal tract
Corticospinal Definition: of or relating to the cerebral cortex and spinal cord or to the corticospinal tract.
The corticospinal tract is a major pathway in the nervous system that carries signals from the brain to the spinal cord, which in turn controls movement in the body.
The tract starts in the motor cortex of the brain, which is responsible for planning and executing voluntary movements. The corticospinal tract then travels down through the brainstem and spinal cord, and ultimately connects to the muscles and other motor neurons in the body.
The corticospinal tract is responsible for fine motor control, such as the precise movements required for writing or playing a musical instrument. It also plays a critical role in gross motor movements, such as walking or running.
Pronunciation: cor-ti-co-bul-bar tract
Corticobulbar Definition: relating to or connecting the cerebral cortex and the medulla oblongata.
The corticobulbar tract is a group of nerve fibers that run from the cerebral cortex of the brain to the brainstem, and are responsible for controlling many of the muscles in the head and neck.
This tract helps to control movements of the face, tongue, throat, and voice box.
Pronunciation: co-ti-co-pon-tine tract
Corticopontine Definition: relating to or connecting the cerebral cortex and the pons.
The corticopontine tract is a group of nerve fibers that connect the cerebral cortex, the outer layer of the brain responsible for many important functions, to the pons, which is a part of the brainstem located below the midbrain.
This tract is involved in the regulation of movement, specifically in fine-tuning and coordinating movements.
The corticopontine tract provides information about movement planning and execution to the pons, which is responsible for relaying this information to the cerebellum, another important structure involved in movement control.
Brain Lobes and Cortexes
The forebrain has four lobes and several cortexes that make up its structure. They control cognitive functions, motor functions, and awareness and perception.
Pronunciation: ce-re-bral cor-tex
Cerebral Definition: of or relating to the brain or the intellect.
Cortex Definition : the outer or superficial part of an organ or bodily structure.
Before you go inside the brain, it’s important to know what the outer part of the brain is called.
The cerebral cortex is the outer layer of the brain, which covers the rest of the brain like a blanket. It is the part of the brain that is responsible for many of our complex mental processes, such as thinking, feeling, and perceiving the world around us.
The cerebral cortex is divided into different regions, each of which is specialized for different functions: the frontal cortex, the parietal cortex, and the temporal cortex. The cerebral cortex is also divided into two hemispheres: the left and the right. The two hemispheres are connected by a thick bundle of nerve fibers called the corpus callosum, which allows them to communicate with each other.
The Frontal Lobe
Pronunciation: fron-tal lōb
Frontal Definition: of, relating to, or adjacent to the forehead or the frontal bone
Lobe Definition: a usually somewhat rounded projection or division of a bodily organ or part
The frontal lobe is a part of the brain that is located in the front part of the skull, just behind the forehead. It is the largest lobe of the brain and is responsible for many of our higher cognitive functions, such as decision-making, problem-solving, planning, and creativity.
Pronunciation: pre-fron-tal cor-tex
Prefrontal Definition: anterior to or involving the anterior part of a frontal structure.
The prefrontal cortex is a part of the brain located at the front of the frontal lobe, just behind the forehead. It is involved in a range of cognitive functions, including decision-making, working memory, planning, and problem-solving.
The prefrontal cortex is also important for regulating our emotions and behavior. It helps us to control our impulses and make good choices. It is also involved in social behavior, empathy, and understanding the thoughts and feelings of others.
Pronunciation: mo-tor cor-tex
Motor Definition: one that imparts motion.
The motor cortex is a region of the brain that is involved in the planning, control, and execution of voluntary movements. It is located in the frontal lobe of the brain as well.
The motor cortex sends signals to the muscles of the body, allowing us to move our limbs and control our facial expressions. It is organized in a specific way, with different parts of the cortex controlling different parts of the body.
Pronunciation: Bro-ca’s ar-ea
Broca's area is a region of the brain that is involved in speech production. It is located in the left hemisphere of the brain, in the frontal lobe, near the motor cortex that controls the movements of the mouth and tongue.
When we speak, Broca's area helps to coordinate the complex series of movements required to produce speech. It also plays a role in the planning and organization of language, helping to put words and sentences together in a meaningful way.
The Parietal Lobe
Pronunciation: pa-ri-e-tal lōb
Parietal Definition: of or relating to the walls of a part or cavity.
The parietal lobe is near the top and back of the head. It processes information related to our sense of touch, spatial awareness, and perception.
The parietal lobe is involved in tasks such as understanding and interpreting the surrounding environment, perceiving and recognizing objects, and understanding how our bodies are positioned in space.
It also helps us to make sense of sensory information from our skin and muscles, such as temperature, pressure, and pain.
Pronunciation: so-ma-toe-sen-so-ry cor-tex
Somato Definition: body.
Sensory Definition: of or relating to sensation or to the senses.
The somatosensory cortex is a region of the brain that receives and processes sensory information from different parts of the body.
It is located in the parietal lobe and is responsible for processing touch, temperature, pressure, pain, and proprioception (the sense of where the body is in space).
The Temporal Lobe
Pronunciation: tem-po-ral lōb
Temporal Definition: a bodily part (such as a bone or muscle) that is near the temples or the sides of the skull behind the orbits.
The temporal lobe is a region of the brain that is on the sides of the head, just above the ears.
It plays a critical role in processing sensory information related to hearing, language, and memory. The temporal lobe also plays a key role in memory formation and retrieval.
It contains the hippocampus, a structure that is critical for the formation of new memories, as well as other areas involved in the storage and retrieval of long-term memories.
The hippocampus is a structure within the brain's temporal lobe that plays a crucial role in the formation and retrieval of memories. It is shaped like a seahorse, which is where it gets its name (the Greek word hippocampus means "seahorse").
The hippocampus works by converting short-term memories into long-term memories, a process called memory consolidation. It also helps to organize memories and retrieve them when needed.
The subiculum is a region of the brain in the temporal lobe that is involved in memory and spatial navigation.
It is part of the hippocampal formation and is one of the main output regions of the hippocampus. The subiculum is important for processing information related to location as well as integrating information from different parts of the brain to form a complete memory.
Pronunciation: au-di-to-ry cor-tex
Auditory Definition: of, relating to, or experienced through hearing.
The auditory cortex is the part of the brain that processes sound. It is in the temporal lobe.
It receives and processes auditory information from the ears and helps us to identify and interpret different sounds, such as speech and music. It is involved in various processes, including sound recognition, sound localization, and speech perception.
Pronunciation: in-fe-ro-tem-po-ral cor-tex
Inferotemporal Definition: being the inferior part of the temporal lobe of the cerebral cortex.
The inferotemporal cortex is a part of the brain that is located in the lower part of the temporal lobe, and it helps us recognize objects and make sense of what we see.
It receives information from our eyes and other parts of the brain that process visual information, and uses this information to create a picture. The inferotemporal cortex is especially important for recognizing specific objects, like faces and animals.
Pronunciation: Wer-nick-e’s ar-ea
Wernicke's area is a part of the brain located in the left temporal lobe that is responsible for language comprehension. It is named after Carl Wernicke, a German neurologist who first identified this area.
When we hear language, the sounds are processed in the auditory cortex and then sent to Wernicke's area for interpretation. This area helps us to understand the meaning of words and sentences, and to recognize the grammar and syntax of language.
Damage to Wernicke's area can result in a language disorder called Wernicke's aphasia, where individuals have difficulty understanding language, but can still produce speech that is fluent, yet often nonsensical.
The amygdala is a small almond-shaped structure located deep within the brain's temporal lobe. It is a part of the limbic system and plays an important role in processing emotions, particularly fear and aggression.
The amygdala is involved in the formation and storage of emotional memories and in recognizing the emotional significance of sensory stimuli. It also plays a role in regulating the body's response to stress and in coordinating emotional responses with other parts of the brain.
The Occipital Lobe
Pronunciation: oc-cip-i-tal lōb
Occipital Definition: of, relating to, or located within or near the occiput or the occipital bone.
The occipital lobe is located at the back of the brain. It is primarily responsible for processing visual information from the eyes, such as recognizing shapes, colors, and motion, and constructing a visual image of the world around us.
The occipital lobe is also involved in activities related to spatial awareness and perception, and plays a crucial role in activities like reading and driving.
Pronunciation: vi-su-al cor-tex
Visual Definition: of, relating to, or used in vision.
The visual cortex, also known as the striate cortex or V1, is a region in the brain that is responsible for processing visual information. It is located in the occipital lobe at the back of the brain and is the first area to receive and interpret visual signals from the eyes.
The visual cortex is responsible for many aspects of vision, including recognizing shapes, colors, and patterns, as well as depth perception and motion detection.