The Brain Part I: Cerebrum, Diencephalon, Cerebellum, and Brainstem

Cerebrum

Largest portion of the brain, responsible for many higher neurological functions such as memory, emotion, language, and consciousness

Cerebral cortex

Thin layer of grey matter on the outside of the cerebrum, highly folded creating sulci and gyri, responsible for higher functions of the nervous system

Cerebral hemispheres

Two distinct halves of the cerebrum, anatomically identical but functionally different, right-imagination/music/art, left-analytical thinking/math/language

Hemispheric lateralization

The differences in function between the cerebral hemispheres

Sulci

Grooves between the ridges of the brain

Gyri

Ridges along the surface of the brain

Median longitudinal fissure

Large separation between the two sides of the cerebrum

Central sulcus

Separates the parietal lobe from the frontal lobe

Lateral sulcus (Sylvain fissure)

Separates the temporal lobe from the frontal and parietal lobes

Parieto-occipital sulcus

Separates the occipital lobe from the parietal lobe

Corpus callosum

Largest commissure of the brain, connecting the vast majority of the right and left hemispheres

Anterior commissure

Commissure connecting the left and right medial temporal lobes of the brain

Association Fibers

Myelinated axons that connect different areas of the cerebral cortex

Projection Fibers

Myelinated axons that extend from the cerebral cortex to the brain stem and spinal cord

Brodmann’s areas

Anatomically distinct areas within the cortex that correspond to different functional areas

Motor areas

Functional regions of the brain that execute the motor response to sensory information

Sensory areas

Functional regions of the brain that process incoming sensory information

Multimodal association areas

Functional regions of the brain responsible for complex processing and integration of the different types of sensory input coming in at a given time along with memories and emotions, planning responses

Insula

Region of the parietal lobe deep to the lateral sulcus, contains the primary gustatory cortex that processes taste information, very developmentally old

Occipital lobe

Posterior region of the cortex responsible for processing visual information

Frontal lobe

Anterior region of the cortex involved in motor activity and higher-order thinking and personality

Prefrontal cortex

Anterior portion of the frontal lobe, responsible for higher-cognitive functions like planning, making decisions, judgement, multitasking, etc, collectively called executive functions

Dorsolateral prefrontal cortex

Section of the prefrontal cortex involved in executive functions and working memory

Executive functions

High functions of the brain including organization and planning, managing behavior, high-level decision-making, and multitasking

Orbitofrontal cortex

Section of the prefrontal cortex involved in modulating emotions, inhibition, and adaptive learning associated with rewards and emotions

Anterior cingulate cortex

Section of the prefrontal cortex involved in motivational behavior, reward-based learning including error detection and outcome monitoring, and pain processing (ALS fibers)

Precentral gyrus

Space in the frontal lobe that houses the primary motor cortex, just anterior to the central sulcus

Primary motor cortex

Region of the frontal lobe located in the precentral gyrus, house the upper motor neurons of the somatic nervous system

Motor homunculus

Arrangement pattern of the primary motor cortex, creates a topographical map of the body

Supplementary area

Region of the frontal lobe hypothesized to be responsible for planning and coordinating movement, manages sequential movements based on prior experience

Premotor area

Region of the frontal lobe that aids in controlling movements of the core muscles to maintain posture during movement

Broca’s area (motor speech area)

Region of the frontal lobe responsible for controlling movements of the structures of speech production, only located in the left hemisphere

Broca’s aphasia

Result of damage to Broca’s area, patient can understand spoken language but has difficulty communicating verbally

Parietal lobe

Region of the cortex located posterior to the central sulcus, anterior to the occipital lobe, and superior to the lateral sulcus, involved in sensory processing (end of the DCML pathway)

Postcentral gyrus

Space in the parietal lobe located posterior to the central sulcus, houses the primary somatosensory cortex

Primary somatosensory cortex

Region of the parietal lobe located in the postcentral gyrus, in charge of the initial processing of all tactile senses

Somatosensory homunculus

Arrangement pattern of the somatosensory cortex, creates a topographical map of the body

Somatosensory association areas

Posterior regions of the parietal lobe that integrate additional senses such as visual stimuli

Wernicke’s area

Area located in the left temporal and parietal lobes that is critical for the comprehension of language

Wernicke’s aphasia

Result of damage to Wernicke’s area, patient has impaired repetition and comprehension but is able to speak fluently, speech is wordy but meaningless

Temporal lobe

Region of the cortex located on the lateral aspect of the brain, near the ears, functions in hearing

Superior, middle, and inferior gyri

The three parallel horizontal gyri of the temporal lobe

Hippocampus

Structure of the limbic system located in the medial temporal lobe, just posterior to the amygdala, critical for the storage of new episodic memories into long-term memory

Amygdala

Structure of the limbic system located in the medial temporal lobe just anterior to the hippocampus, critical for processing emotions and tying emotions to our sensations and our current environment

Limbic system

Collection of structures involved in emotion, memory, and behavior

Basal nuclei

A set of nuclei deep in the cerebrum involved in controlling subconscious aspects of movement, contains three major structures, connect with a new more nuclei in the brain stem and diencephalon to form a motor pathway

Caudate

Structure of the basal ganglia, a long nucleus that follows the basic C-shape of the cerebrum from the frontal lobe, through the parietal and occipital lobes, into the temporal lobe

Putamen

Structure of the basal ganglia, mostly deep in the anterior regions of the frontal and parietal lobes

Globus Pallidus

Structure of the basal ganglia, layered nucleus that lies just medial to the putamen

Rostral

Orientation of the CNS, towards the nose

Caudal

Orientation of the CNS, towards the back of the skull in the brain and towards the tail in the spinal cord

Ventral

Orientation of the CNS, superior in the brain and anterior in the spinal cord

Dorsal

Orientation of the CNS, inferior in the brain and posterior in the spinal cord

Telencephalon

Developmental region of the brain the becomes the cerebrum

Diencephalon

Deeper developmental region of the brain that consists of every structure with “thalamus“ in the name

Mesencephalon

Developmental region of the brain that becomes the midbrain

Metencephalon

Developmental region of the brain that becomes the pons and cerebellum

Myelencephalon

Developmental region of the brain that becomes the medulla oblongata, consists of many myelinated axons because it connects to the spinal cord

Thalamus

Structure of the diencephalon, collection of nuclei that relay and process information between the cerebral cortex and the spinal cord or brain stem, left and right together form the walls of the third ventricle

Hypothalamus

Structure of the diencephalon, inferior and slightly anterior to the thalamus, executive region in charge of the autonomic nervous system and the endocrine system through regulation of the pituitary gland, both neural and endocrine functions and produces and secretes many hormones

Pituitary Gland

Gland of the hypothalamus

Anterior pituitary/adenohypophysis

Lobe of the pituitary gland, glandular tissue that releases or inhibits hormones from the hypothalamus

Posterior pituitary/neurohypophysis

Lobe of the pituitary gland, neural tissue that regulates the secretions of hormones from the hypothalamus and stores them

Infundibulum

A “stalk“ of connections that connects the hypothalamus to the pituitary gland

Cerebellum

Part of the brain that makes up about 10% of the mass, largely responsible for comparing information from the cerebrum with sensory feedback from the periphery through the spinal cord, coordinates primarily motor control but also higher cognitive functions and emotions

Cerebellar peduncles

Regions of the cerebellum that contain white matter pathways traveling to or from it, has a superior, middle, and inferior portion

Superior peduncle

The peduncle of the cerebellum that connects with the midbrain

Middle peduncle

The peduncle of the cerebellum that connects with the pons

Inferior peduncle

The peduncle of the cerebellum that connects with the medulla

Folia

Ridges of the cerebellum, appear more feathered or leaf-like than those of the cerebrum

Anterior lobe

Lobe of the cerebellum located anterior to the primary fissure

Posterior lobe

Lobe of the cerebellum located posteriorly not the primary fissure

Primary fissure

Separates the anterior and posterior lobes of the cerebellum

Vermis

The midline portion of the cerebellum between the two cerebellar hemispheres

Flocculonodular lobes

The smaller lobes of the cerebellum located anteriorly

Brainstem

Portion of the brain that contains structures responsible for many unconscious features, the origin for 10 cranial nerves

Reticular Formation

Diffuse region of gray matter throughout the brain stem, related to sleep and wakefulness

Midbrain

The superior, small portion of the brain stem

Tectum

Midbrain structure composed of four bumps

Corpora quadrigemina

The two pairs of two bumps (4 total) that make up the tectum of the midbrain

Superior colliculi

Pair of colliculi in the tectum important for visual reflexes

Inferior colliculi

Pair of colliculi in the tectum important for auditory reflexes

Substantia nigra

Structure of the midbrain that is part of a neural circuit with the basal ganglia, contributes to motor control and modulation

Red nucleus

Structure of the midbrain that is involved in motor regulation and muscle tone through connections with other parts of the brain

Cerebral peduncles

Connect the midbrain to the cerebellum

Pons

The middle, anterior portion of the brain stem, the main connection between the cerebellum and the brain stem

Medulla

The most inferior portion of the brain stem, contains a significant amount of white matter continuous with the columns of the spinal cord

Pyramids

Two vertical ridges on the anterior aspect of the medulla formed by the axons of the corticospinal tract

Pyramidal decussation

The area on the inferior aspect of the anterior medulla where the corticospinal tract fibers cross

Cardiovascular center

Nuclei in the medulla that control the smooth and cardiac muscle of the cardiovascular system through autonomic connections

Medullary respiratory center

Section of the medulla that communicates with the respiratory center of the pons to regulate breathing