Chapter 14: Brain

Cerebrum

largest brain region; conscious thought, intellectual functions, memory, sensations, and complex voluntary movement

Cerebellum

coordinates ongoing and learned movement and adjusts motor output; imporatnt for balance and equilibrium

Diencephalon

includes thalamus and hypothalamus; integrates sensory, autonomic, endocrine, and emotional functions

Brainstem Parts

midbrain, pons, and medulla oblongata

Brainstem Function

relays information between spinal cord and higher brain regions and contains importnat motor/autonomic centers

Gyri

raised folds

Sulci

shallow grooves

Fissures

deeper grooves

Cerebral Cortex

superficial gray matter of cerebral hemisphere

Cerebrum Hemisphers

left and right

Embryonic Development Sequence

neural tube, prosencephalon, mesencephalon, rhombencephalon

Neural Tube

three primary brain vesicles: prosencephalon (forebrain), mesencephaon (midbrain), rhomboencephalon (hindbrain)

Prosencephalon

telencephalon (cerebrum) and diencephalon

Mesencephalon

midbrain

Rhomboencephalon

metencephalon (cerebellum and pons) and myelencephalon (medulla oblongata)

Ventricles

two lateral ventricles, third ventricles, cerebral aqueduct, fourth ventricle

Two Lateral Ventricles

one in each cerebral hemisphere; separated by the septum pellucidum

Third Ventricle

in the diencephalon; communicates with lateral ventricle through interventricular foramina

Cerebral Aqueduct

narrow channel through the midbrain connecting third and fourth ventricles

Fourth Ventricle

associated with pons/medulla and cerebellum, continues into the central canal of the spinal cord

Three Levels of Protection

physical protection, biochemical protection, cranial meninges

Physical Protection

skull, cranial meninges, and CSF

Biochemical Protection

blood-brain barrier (BBB)

Cranial Meninges

dura mater, arachnoid mater, pia mater

Dura Mater

outermost; periosteal and meningeal layers; dural folds stabilize/support the brain

Falx Cerebri

between cerebral hemispheres; associated with sagittal sinuses

Tentorium Cerebelli

separates cerebellar hemispheres

Arachnoid Mater

middle layer; subarachnoid space lies beneath it and contains CSF

Pia Mater

innermost layer; tightly follows the brain surface

Subdural Space

lies between dura and arachnoid; a narrow gap that forms with trauma/disease

Choroid Plexus

produces CSF using specialized ependymal cells surrounding capillaries

CSF

supports/buoys the brain, cushions the CNS, chemical messengers, and wastes

Flow of CSF

choroid plexus → ventricles → central canal and/or fourth-ventricle apertures → subarachnoid space → arachnoid villi/granulations → venous circulation

Blood Brain Barrier

capillary endothelial cells joined by tight junctions; astrocytes regulate permeability; lipid-soluble substances can generally diffuse across the BBB; glucose is actively transported; ion transport is regulated

Blood-CSF Barrier

specialized ependymal cells of the choroid plexus with tight junctions limit transfer into CSF

BBB: Circumventricular Organs

contain breaks in BBB e.g. portions of hypothalamus, posterior pituitary, pineal gland, and choroid plexus where ependymal cells maintain the blood-CSF barrier

Medulla Oblongata

most inferior part of the brainstem; connects the brain with the spinal cord; contains reflex/autonomic centers, cranial nerve nuclei, and relay stations along sensory and motor pathways

Reticular Formation

contributes to regulation of breathing, blood pressure, and thermoregulation

Cardiovascular Centers

adjust heart rate, cardiac contractility, and peripheral blood flow

Respiratory Rhythmicity Centers

establish the basic pace of respiratory movements; influenced by respiratory centers in the pons

Gracile and Cuneate Nuclei

relay somatic sensory information toward the thalamus; associated fibers cross at the decussation of pyramids

Solitary Nuclei

receieve and integrate visceral sensory information and relay it to autonomic centers

Inferior Olivary Complex

relays motor-related information toward the cerebellum

Pons

contains sensory and motor nuclei of cranial nerves, apneustic and pnuemotaxic respiratory centers, nuclei and tracts; links cerebellum with midbrain, cerebrum, diencephalon, and spinal cord

Apneustic and Pnuemotaxic Respiratory Centers

adjust the activity of medullary respiratory rhythmicity centers

Pons Nuclei and Tracts

process/relay information to and from the cerebellum

Pons: Transverse Pontine Fibers

connect pontine nuclei with the opposite cerebellar hemisphere

Midbrain

tectum, superior and inferior colliculi, tegementum, red nucleus, substantia nigra, cerebral peduncles

Tectum

roof of midbrain, posterior to cerebral aqueduct

Superior Colliculi

visual information and visual reflexes

Inferior Colliculi

auditory information and auditory reflexes

Tegmentum

lies anterior to the cerebral aqueduct

Red Nucleus

receives cerebral/cerebellar input; contributes to subconscious upper-limb motor control and muscle tone

Substantia Nigra

dopamine-producing nucleus involved in regulation of basal nuclei; affected in Parkinson disease

Cerebral Peduncles

fiber bundles carrying major motor pathways and other ascending/descending information

Cerebellum

an automatic processing/coordination center for patterns of muscular activity; balance/equilibrium, fine-tuning conscious and subconscious movement, refining learned movement patterns, matching motor commands with propioceptive information

Cerebellar Cortex

gray matter surface and folia (folds)

Primary Fissure

separates anterior and posterior lobes of cerebellum

Cerebellar Hemispheres

separated by vermis

Flocculonodular Lobe

lies near the roof of the fourth ventricle

Arbor Vitae

internal white matter; contains/communicates with cerebellar nuclei

Superior Peduncle

links cerebellum with midbrain/diencephalon/cerebrum

Middle Peduncle

links with pons

Inferior Peduncle

links with medulla/spinal cord

Ataxia

impaired muscular coordination; the deck notes trauma/stroke as causes and temporary ataxia with alcohol intoxication

Diencephalon

epithalamus, thalamus, hypothalamus

Epithalamus

forms the roof of diencephalon; contains pineal glad

Pineal Gland

secretes melatonin and associated with day-night cycles

Thalamus Function

forms lateral walls of diencephalon; filters and relays sensory information from spinal cord/cranial nerves to the cerebral cortex; relays information between basal nuclei and cerebral cortex

Thalamus Components

contains anterior nuclei, medial nuclei, ventral nuclei, dorsal nuclei, lateral geniculate body

Anterior Nuclei

limbic/emotional functions

Medial Nuclei

awareness of emotional states through hypothalamic-cerebral connections

Ventral Nuclei

relay motor information from basal nuclei/cerebellum and sensory information such as touch, pressure, pain, temperature, and propioception

Dorsal Nuclei

integrate sensory information for cortical transmission

Lateral Geniculate Body

visual relay

Medial Geniculate Body

auditory relay

Hypothalamus

coordinates nervous and endocrine systems and regulates autonomic functions; produces ADH and oxytocin; regulates body temperature, circadian rhythms, feeding, thirst, and satiety; controls endocrine activity through the pituitary and influences emotional/behavioral drives

Hypothalamus: Suprachiasmatic Nucleus

regulates circadian rhythms