Brain Structure and Nervous System

• The concept explored is the structure of the brain.

Nervous System Basics Review

• The neuron is the nervous system's structural unit
• Nucleus is located within the yellow circle
• Axon Hillock is represented by the black triangle
• Axon is represented by the black arrow
• Dendrite is represented by the blue arrows

Structural Divisions of the Nervous System

• The components of the central nervous system (CNS) are the brain and the spinal cord
• The peripheral nervous system (PNS) consists of everything else and includes cranial, spinal, and peripheral nerves

Gray Matter vs. White Matter

• Nucleus/Nuclei refers to a collection of cell bodies inside the CNS
• Ganglion/Ganglia refers to a collection of cell bodies outside the CNS
• Nerve/Nerve fiber is a collection of axons
• Tract is a collection of nerve fibers that share a common function
• Gray matter is the location of cell bodies (nuclei) inside the CNS
• White matter is the location of myelinated axons inside the CNS
• In the brain, gray matter is superficial, while white matter is deep
• White matter tracts within the CNS consist of association, commissural, and projection tracts
• Association tracts connect the same hemisphere
• Commissural tracts connect opposite hemispheres and cross via the Corpus Callosum
• Projection Tracts project to lower regions of the brain and spinal cord

Divisions of the Brain

• The divisions of the brain are the cerebrum, cerebellum, and brainstem
• The brainstem consists of the midbrain, pons, and medulla

Cerebrum

• The cerebrum is divided into right and left hemispheres
• Cerebral hemispheres are connected by the corpus callosum
• Each hemisphere is structurally divided into four lobes: frontal, parietal, temporal, and occipital

Functions of the Cerebrum

• Frontal lobe functions include personality, primary motor cortex, and memory
• Parietal lobe function include primary sensory cortex
• Temporal lobe function includes primary auditory cortex
• Occipital lobe function includes primary visual cortex
• Cortex is defined as neurons with similar structures coming together to perform a function
• Association areas in the frontal lobe are where motor and sensory functions are integrated
• Broca’s area contains motor neurons involved in the control the speech
• Wernicke’s Area is located in the temporal lobe, is where spoken language is understood

Features of the Cerebrum

• Fissures are deep grooves or clefts
• Longitudinal fissure is located between the left and right hemispheres of the cerebrum
• Transverse fissure is located between the cerebrum and cerebellum
• Sulcus is a shallow groove
• Central Sulcus is located between the precentral gyrus and postcentral gyrus
• Lateral sulcus separates the temporal lobe from the frontal and parietal lobes
• Gyrus is a ridge
• Precentral Gyrus is the primary motor cortex
• Postcentral Gyrus is the primary sensory cortex

Diencephalon

• Diencephalon consists of three paired structures: the thalamus, hypothalamus, and epithalamus

Diencephalon-Thalamus

• The thalamus receives, groups and relays the sensory information to the cerebrum
• The thalamus directs sensory information to where it needs to go, with the exception of smell (olfactory)
• It is considered the "Crossing Guard" of the Diencephalon

Function of Hypothalamus

• The hypothalamus is the command center for the endocrine system
• The hypothalamus tells the pituitary gland what to do
• Homeostasis Light House because it regulates functions like body temperature, food and water intake, sleep and circadian rhythms, emotional responses and memory

Function of Epithalamus

• The pineal gland produces Melatonin to regulate the sleep/wake cycles
• Low production of Melatonin can lead to SAD (seasonal affective disorder)

Basal Nuclei

• Basal Nuclei is paired, contains irregular masses of gray matter buried deep within the central white matter in the cerebral hemispheres

Function of the Basal Nuclei

• The irregular masses work together to select which actions the cerebrum "allowed" to initiate in a given instance

Cerebellum

• Superficial cortex gray matter makes up the gray matter of the cerebellum
• Arbor Vitae makes up the white matter of the cerebellum
• The cerebellar hemispheres are the left and right "wings" of the cerebellum

Function of Cerebellum

• The cerebellum functions in body posture, balance, and fine coordination
• The cerebellum does not initiate movement but helps to maintain movement

Divisions of the Brainstem

• The brainstem consists of the midbrain, pons, and medulla.

Function of the Midbrain

• The midbrain is the superior portion of the brainstem
• The midbrain also functions as a relay station for visual and auditory information

Function of the Pons

• The pons is directly inferior to the midbrain
• In Latin, "pons" means bridge
• The pons serves as a communication and coordination center for the spinal cord and various portions of the brain i.e cerebral cortex, cerebellum

Function of Medulla

• The medulla is directly inferior to the pons
• A continuation of the medulla is the spinal cord
• The medulla controls autonomic (involuntary) functions i.e breathing, heart rate