Bio 209 Ch 14

Brain Stem: continuous with spinal cord; consists of medulla oblongata, pons, midbrain

Diencephalon: superior to brain stem; consists of hypothalamus, thalams, epithalamus

Cerebellum: posterior to brain stem

Cerebral Hemisphere (Cerebrum): largest part of brain; sits on diencephalon

Cranium: formed by cranial bones

• Cranial Meninges: continuous with spinal meninges
• - Dura Mater, Arachnoid Mater, Pia Mater

Falx Cerebri: separates the two hemispheres of the cerebrum

Falx Cerebelli: separates the two hemispheres of the cerebellum

Tentorium Cerebelli: separates cerebrum and cerebellum

• Structure:
• - Tight Junctions: transmembrane proteins fuse together portions of adjacent epithelial cells so material cannot diffuse between cells; there are spaces between fused areas
• - Astrocytes: processes surrounds capillaries help form BBB
• Function:
• - Protects brain from harmful substances and pathogens
• - Controls entry of nonlipid soluble (hydrophilic) substances into brain from blood
• . Glucose can cross thru by Active Transport
• . Ions cross thru slowly
• . Proteins and most antibiotics cannot cross thru
• . Drugs that can be used to treat cancer and CNS diseases
• - Cannot prevent passage of lipid soluble (hydrophobic) substances into brain. The follwing can cross easily:
• . O, Carbon Dioxide, Alcohol, some Anesthetic Agents, lipid soluble drugs

• (1) Protects brain & spinal cord
• (2) Mechanical protection of CNS
• (3) Transports O, Glucose, other chemicals from blood to neurons/neuroglia
• (4) Movement of ependymal cell cilia circulates CSF thru ventricles (spaces) in brain and in the subarachnoid space of the brain and spinal cord
• (5) Provides optimal chemical environment
• (6) Exchanges nutrients/wastes between blood and nervous tissue

- Formed in Choroid Plexuses (capillary networks in walls of ventricles)

- Ependymal cells cover capillaries and filter fluid leaving capillaries form CSF

- Tight junctions between ependymal cells help form the BBB

• Lateral Ventrical to Interventricular Foramen (hole in each lateral ventricle) to
• Third Ventricle to Cerebral Aqueduct (tunnel-like space in midbrain) to
• Fourth Ventricle to
• Lateral & Median Apertures to
• Subarachnoid Space & Central Canal of Spinal Cord to
• Reabsorbed through to
• Arachnoid Villi

• (1) Medulla Oblongata
• (2) Pons
• (3) Midbrain

• - Located between Foramen Magnum & Pons
• - Sensory Tracts, Motor Tracts, Nuclei (controls body functions & nuclei that are part of sensory pathways
• - Function of Nuclei
• 1. Controls vital body functions:
• . Cardiovascular Center (BP, HR, contractions, BV diameter)
• . Respiratory Center (regulates respiratory rhythm)
• 2. Reflexes for vomiting, swallowing, sneezing, coughing, hiccups
• 3. Somatic Sensory Pathways (touch, pressure, vibration, proprioception) and sensory pathways for taste, hearing, balance
• 4. Adjusting muscle activity when learning new motor skills like piano, biking etc
• 5. Associated with Cranial Nerves (VIII, IX, X, XI, XII)

Superior to medulla, Anterior to Cerebellum

Sensory Tracts (ascending)

Motor Tracts (descending) connects to Cerebellar Hemispheres

Nuclei: helps control breathing (Pneumotaxic & Apneustic areas); Nuclei for cranial nerves (V-VIII)

Between Pons and Diencephalon

- Ascending Sensory & Descending Motor Tracts: Cerebral Penduncles contain axons that relay motor info from Cerebral Cortex to Spinal Cord, Pons, Medulla

• - Nuclei for controlling movements of head, eyes, trunk in response to visual/auditory stimuli: (1) Superior Colliculi control movements in response
• to visual stimuli (2) Inferior Colliculi control movements in response to auditory stimuli

- Other nuclei that control subconscious and conscious muscle movements. Loss of neurons in one of these nuclei (substantia nigra) associated with Parkinson’s

Location: extends from spinal cord to diencephalons

Structure: netlike structure of gray and white matter

• Function: (1) Reticular Activating System (RAS) are fibers that send sensory signals to cerebral cortex that
• maintains consciousness and awakens us from sleep (2) Regulates muscle tone

• Location: Posterior to Medulla and Pons, Inferior to Cerebrum
• Structures:
• (1) Cerebellar Hemispheres
• - 3 lobes per hemisphere
• - Anterior/Posterior lobes control subconscious movements of skeletal muscles
• - Flocculondular Lobe plays a role in equilibrium and balance
• (2) Vermis located on central part of cerebellum between cerebellar hemispheres

Thalamus, Hypothalamus, Epithalamus

• - 80% of Diencephalon
• - Functions:
• (1) Relays most sensory info to cerebral cortex, internal capsule
• (2) Relays motor info from cerebellum and basal nuclei to motor area of cerebral cortex (cerebral cortex is outer layer of cerebrum and is compose of gray matter)
• (3) Plays role in maintaining consciousness

• - Located inferior to Thalamus
• - Functions: (1) Controls ANS (2) Controls Pituitary Gland thru hormones and nerve impulses; Infundibulum connects Hypothalamus to Pituitary Gland (3) Regulates emotions/behavior patterns associated with sexual arousal (4) Regulates eating/drinking; Feeding, Satiety, Thirst Centers (5) Control body temp (6) Biological Clock; Circadian or Sleep-Wake Cycles

• - Superior & Posterior to Thalamus
• - Functions: contains (1) Pineal gland which secretes melatonin and (2) Habenular Nuclei which is involved in olfaction and emotional response to odor

Location: walls of third/fourth ventricles

Functions: (1) Monitor chemical changes in blood because lack of BBB (2) Participates in regulation of BP, fluid balance, hunger, thirst

Gray Matter: located outside of brain

White Matter: located deep to cortex

Location: gray matter on outside of brain

Function: (1) Sensory areas contribute to sensory perception (2) Motor areas control voluntary skeletal muscle movements (3) Associated areas involved in memory, personality traits, intelligence

• Structures:
• (1) Gyri are folds of the Cerebral Cortex
• (2) Sulci are shallow groove
• (3) Fissures are deep grooves
• (4) Longitudinal Fissure:
• - Separates Cerebrum into right and left Cerebral Hemispheres
• - Falx Cerebri extends into Longitudinal Fissure

Longitudinal Fissure separates Cerebrum into right and left Cerebral Hemispheres; Falx Cerebri extends into Longitudinal Fissure

Lobes: Frontal, Parietal, Occipital, Temporal

Central Sulcus: separates Frontal and Parietal

Precentral Gyrus: anterior to Central Sulcus

Postcentral Gyrus: posterior to Central Sulcus

Parieto-Occipital Sulcus: separates Parietal and Occipital

Lateral Cerebral Sulcus: separates Frontal from Temporal

Insula: gray matter deep to lateral Cerebral Sulcus

Location: deep within cerebral hemispheres

Function: (1) Help control skeletal muscle movements (2) Regulate muscle tone

Location: ring of structures found in border between cerebrum & diencephalons

Function: (1) Emotions (2) Memory from Hippocampus

Sensory Areas: receive sensory info and involved in perception

Motor Areas: initiate voluntary movement

Association Areas: complex integrative functions such as memory, emotions, reasoning, will, judgment, personality, intelligence

• Primary Somatosensory Area
• Location: Postcentral Gyrus of each cerebral hemisphere
• Function: localize point(s) on body stimulated
• Primary Visual Area
• Location: Occipital Lobe
• Function: receives visual info and involved in visual perception
• Primary Auditory Area
• Location: Temporal Lobe
• Function: receives auditory info and involved in auditory perception
• Primary Gustatory Area
• Location: Parietal Lobe
• Function: receives impulses for taste and involved in gustatory perception and taste discrimination
• Primary Olfactory Area
• Location: Temporal Lobe
• Function: receives impulses for small and involved in olfactory perception

The greater the density, the larger the area of the corresponding cerebral cortex

Contralateral

• Primary Motor
• - Location: Precentral Gyrus in each hemisphere
• - Function: controls voluntary contraction of skeletal muscles

• Broca’s
• - Location: left Frontal (for most)
• - Function: articulation of speech

The smaller the muscle, the smaller the motor unit

Opposite

(1) Left side of brain important for language and math

(2) Right side of brain important for art, spatial discrimination, facial recognition, emotional content of language, generating mental images of sight, sound, touch, taste, smell for comparison

• - Brain waves produced by action potentials generated by neurons
• - EEG = Electroencephalogran is a recording of brain waves
• - EEG used to study brain functions

- Cranial Nerves I - XII

- On Old Olympus’ Towering Top A Friendly Viking Grew Vines And Hops

- Olfactory, Optic, Occulomotor, Trochlear, Trigeminal, Abducens, Facial, Vestibulocochlear, Glossopharyngeal, Vagus, Accesory, Hypoglossla

- Some Say Marry Money But My Brother Says Bad Business Marry Money

• - Cranial Nerves I-IV
• Olfactory (I): carries info from olfactory receptors
• Optic (II): carries info from vision receptors
• Occulomotor (III): movement of eyeball, pupil size, lens shape
• Trochlear (IV): movement of eyeball
• - Cranial Nerves V-VII
• Trigeminal (V): somatic sensory info from head and face and motor impulses that control chewing
• Abducens (VI): control eyeball movement
• Facial (VII): sensory info from taste receptors, motor impulses to control salivation, tearing, contraction of facial muscles
• - Cranial Nerves VIII-X
• Vestibulocochlear (VIII): carries info from hearing and equilibrium receptors
• Glossopharyngeal (IX): sensory info from taste receptors, motor info controlling salivation, muscle involved in swallowing
• Vagus (X): sensory info from _____, motor info to viscera
• - Cranial Nerves XI-XII
• Accessory (XI): controls muscle involved in swallowing
• Hypoglossal (XII): controls tongue movements during speech