Module 19: The Brain Part I: Cerebrum, Diencephalon, Cerebellum, and Brainstem

Telencephalon

Cerebrum and deep brain structures

Diencephalon

Area of gray matter surrounded by the cerebral hemispheres that has every structure with thalamus, both sensory and motor pathways synapse here

Mesencephalon

Midbrain

Subcortical nuclei function

augment cortical processes

Metencephalon

Pons and cerebellum

Myelencephalon

Medulla oblongata, so it has many myelinated axons traveling through

Cerebrum

Largest portion of the brain, resulting in higher neurological functions

Subcortical nuclei

Below the cerebral cortex and augment cortical processes

Gray matter

Cell bodies, dendrites, unmyelinated axons that form cerebral nuclei

White matter

Myelinated axons

Cerebral nuclei

Discrete internal clusters of gray matter

Gyri

Ridges on the surface of the brain

Hemispheric lateralization

functional differences between the two hemispheres

Sulci

Grooves between the gyri

Gyri and sulci function

Increase surface area of the cortex

Median longitudinal fissure

Large separation between the two sides of the cerebrum, the right and left cerebral hemisphere

Connection between hemispheres

White matter pathways, such as the anterior commissure, corpus callosum, and posterior commissure

Right hemisphere focus

Visuospatial processes, imagination, music, artistic skills

Left hemisphere focus

Analytical thinking, math skills, language centers

Lateral sulcus

Separates temporal from frontal and parietal

Central sulcus

Separates parietal and frontal

Parietooccipital sulcus

Separates parietal and occipital

Cerebral cortex

Thin layer of gray matter on the outside of the cerebrum that covers the surface of the brain, responsible for higher order thinking and cognition, awareness, knowledge, memory, perception, information processing, and thinking

Brodmann’s areas

Areas of the brain that govern a specific function split based on cytoarchitectural differences

Brodmann’s areas groups

Sensory areas, multimodal association areas, motor areas

Sensory areas function

Process incoming sensory information

Multimodal association areas function

Complex processing, integration of sensory input, memories, emotions

Motor areas function

Motor response

Corpus callosum

Connection between right and left hemispheres

Occipital lobe function

Processing visual information

Parietal lobe

Superoposterior part of each hemisphere involved in sensory processing and general sensory functions, information crosses in the brain stem, includes postcentral gyrus and primary somatosensory cortex

Primary sensory function of the parietal lobe

Somatosensation

Primary somatosensory cortex

Area within the postcentral gyrus that receives general somatic sensory info from touch and pressure receptors

Homunculus

Map of human body laid across a portion of the cerebral cortex

Somatosensory homunculus

Map of somatosensory receptors on the somatosensory cortex with lower extremities on medial surface within the longitudinal fissure and upper extremities on the lateral side. Areas with fine touch sensation have more space and areas with less sensation have less space.

Frontal lobe

Anterior to the central sulcus involved in motor activity, higher-order thinking and personality, includes prefrontal cortex, primary motor cortex, dorsolateral prefrontal, orbitofrontal, anterior cingulate, precentral gyrus, and broca’s area

Primary motor cortex

In precentral gyrus, anterior to the central sulcus, part of the corticospinal tract, in charge of voluntary motor activity with a motor homunculus

Motor neurons synapsing

Upper motor neurons originate in frontal lobe and travel to spinal cord to synapse lower motor neurons, information crosses in corpus callosum

Motor homunculus

Map of motor areas on the primary motor cortex with lower extremities in medial surface in longitudinal fissure and upper extremities on the lateral sides. Muscles for fine, agile movements have more space, muscles for bigger movements have less space.

Premotor cortex

Area adjacent to the primary motor cortex that controls movements of core muscles

Supplemental motor area

Area adjacent to the primary motor cortex that plans and coordinates movement

Prefrontal cortex

Anterior portion of the frontal lobe responsible for personality, aspects of attention, and higher-cognitive functions, such as planning, making decisions, judgement, and multitasking, also known as the executive functions

Dorsolateral prefrontal cortex function

Executive functions, such as organization and planning, managing behavior, high-level decision making, multitasking, and working memory

Orbitofrontal cortex function

Modulating emotions, inhibition, adaptive learning, rewards, and emotion

Anterior cingulate cortex function

Motivational behavior, reward-based learning, pain processing

Broca’s area

Lateral aspect of the frontal region only in the left hemisphere, anterior to the region of the motor cortex associated with the head and neck, responsible for controlling movements of structures of speech production

Broca’s aphasia

Patient can understand spoken language but has difficulty communicating verbally

Wernicke’s area

Speech area in the temporal lobe only in the left hemisphere, critical for comprehension of spoken and written language

Wernicke’s aphasia

Patient has fluent speech, but impaired repetition and comprehension

Wernicke’s and Broca’s connection

Wernicke’s and Broca’s are highly connected by white matter pathways

Temporal lobe

Lateral aspect of the brain near the ears in charge of hearing, includes the superior, middle, and inferior temporal gyri, amygdala, and hippocampus

Primary auditory cortices

In superior temporal lobe and the first cortical area involved in processing hearing

Limbic system

Collection of structures in the medial temporal lobe that forms a ring around the diencephalon and is involved in processing and experiencing emotion, establishing emotional states and related behavioral drives, memory, learning, aggression, and behavior, links conscious and unconscious, links memories with senses,

Limbic system structures

Cingulate gyrus, mammillary body, hippocampus, fornix, amygdala, parahippocampal gyrus, some thalamic nuclei, some hypothalamic nuclei

Amygdala

Structure in medial temporal lobe just anterior to the hippocampus that processes emotions, regulates and ties emotions to sensations and the environment, and connects emotions to memories

Hippocampus

Structure just posterior to the amygdala in the medial temporal lobe that is critical for storage of new episodic memories into long-term memory and learning

Procedural memory

Memories for motor activities controlled by the cerebellum

Working memory

Taking in info and using it immediately

Insula

Deep to the lateral sulcus containing the primary gustatory cortex that processes taste information

Basal ganglia

Set of nuclei deep in the cerebrum involved in processing, integrating, and relaying info from the cortex to the thalamus, and controlling aspects of movement, such as posture, pattern and rhythm, muscle tone, and learned movement patterns, along with reward processing, motivation, decision-making, and addiction

Caudate

Long nucleus that follows the C-shape of the cerebrum from frontal through parietal and occipital into temporal that controls movement

Putamen

Deep in the anterior regions of the frontal and parietal lobe that controls movement

Globus pallidus

Layer nucleus just medial to the putamen that controls movement

Epithalamus

Contains pineal gland, which is in charge of the sleep wake cycle

Thalamus

Collection of nuclei that relay and process information between the cerebral cortex and spinal cord or brain stem and communicate motor commands from the cerebrum

Hypothalamus

Executive region inferior and slightly anterior to the thalamus in charge of the ANS and endocrine system through regulation of the pituitary gland, producing and secreting hormones, memory, and emotion

Hypothalamus-pituitary complex

Command center of the endocrine system that secretes several hormones that directly produce response in target tissues and regulate synthesis and secretion of hormones

Pituitary gland

Gland that includes posterior, neural tissue, and anterior, glandular tissue, pituitary lobes

Infundibulum

“Stalk” that connects the hypothalamus to the pituitary gland

Anterior pituitary gland hormone

Adenohypophysis, which are the releasing hormones that stimulate the secretion of hormones from the anterior pituitary and the inhibiting hormones that inhibit secretion

Hypothalamic-hypophyseal portal system

Bridge of capillaries that connects hypothalamus to anterior pituitary lobe, allowing hormones to be transported without entering systemic circulation

Hypothalamic-hypophyseal portal system pathway

Hypothalamic hormones travel through a primary capillary plexus to the portal veins, which carry them into the anterior pituitary. Hormones produced by the anterior pituitary enter a secondary capillary plexus to drain into circulation. Adenohypophysis either releases or inhibits hormones in response.

Posterior pituitary hormone

Neurohypophysis

Posterior pituitary

Extension of the neurons of the hypothalamus, where cell bodies rest in the hypothalamus but axons descend as the hypothalamic-hypophyseal tract within the infundibulum to end in axon terminals. Stores and secretes hormones produced by the hypothalamus.

Cerebellum

“Little brain” that is covered in folia and coordinates motor control, higher cognitive functions, emotion, comparison of descending commands from cerebrum, and corrective commands. Information is ipsilateral. Includes anterior and posterior lobes, smaller flocculonodular lobe, and the vermis.

Primary fissure

Separates the anterior and posterior lobe of the cerebellum

Smaller flocculonodular lobe

Anterior portion of the cerebellum

Vermis

Midline portion between the two cerebellar hemispheres

Superior, middle, and inferior cerebellar peduncles

White matter pathways traveling to or from the cerebellum to create indirect connections to the brain stem, spinal cord, and cerebrum, not all direct connections between the cerebellum and brain stem.

Brain stem

Origin for 10/12 cranial nerves and includes the midbrain, pons, and medulla oblongata that are responsible for unconscious functions

Reticular formation

Diffuse region of gray matter throughout the brain stem that is related to sleep and wakefulness, brain activity, and attention

Midbrain

Small region between the thalamus and pons

Cerebral aqueduct

Duct passing through center of the midbrain

Tetum

Four colliculi

Inferior colliculis

Inferior pair of colliculi important for auditory reflexes

Superior colliculus

Superior pair important for visual reflexes

Red nucleus

Involved in motor regulation and muscle tone through connections with other parts of the brain

Substantia nigra

Part of a neural circuit with the basal ganglia to contribute to motor control and modulation

Pons

Thick belly attached to the cerebellum on the anterior surface of the brain stem that is the main connection between the cerebellum and brain stem through the middle cerebellar peduncle. Gray matter receives descending input from the forebrain that is sent to cerebellum and pontine respiratory center.

Medulla

Most inferior portion of the brain stem with significant continuous white matter of the spinal cord

Pyramids

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

Pyramidal decussation

Area on inferior aspect of the anterior medulla where the corticospinal tract fibers cross where groove between two pyramids briefly disappears

Cardiovascular center

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

Medullary respiratory center

Area within the medulla that communicates with the pontine respiratory center to regulate breathing

Primary routes for brain blood supply

Vertebral arteries, internal carotid arteries

Circle of Willis

Arterial circle formed by vertebral and internal carotid arteries

Association fibers

Connect cortical areas within the same hemisphere

Projection fibers

Connect cerebral cortex to spinal cord and lower brain regions

Cerebral peduncle

Paired, descending motor fibers that travel from the midbrain to spinal cord or brain stem and carry motor info