4 Major Regions of the Brain

- cerebrum

- diencephalon

- brainstem

- cerebellum

Brain Development - Week 4

- neural tube forms 3 primary vesicles

1) prosencephalon - forebrain

2) mesencephalon - midbrain

3)  rhombencephalon - hindbrain

Brain Development - Week 5

primary vesicles form 5 secondary vessicles

1) telencephalon

2) diencephalon

3) mesencephalon

4) metencephalon

5) myelencephalon

Brain Development - Week 9 to 38

posterior flexion/cerebral expansion

1) Cerebrum

the center of our sensory perception, thought, memory, judgement and voluntary motor actions

External structure of cerebrum

- longitudinal fissure

- transverse cerebral fissue (seperates the cerebral hepisheres from cerebellum)

Folds (gyrus)/ Grooves (Sulcus) of the cerebrum

Central and lateral sulcus

Internal Structure of the cerebrum

-outer area is gray matter; inner is white

- deep to the white matter are discreet areas of gray matter called "nuclei

- ventricles

5 functional areas (lobes) of cerebrum

-frontal

-parietal

-temporal

-occipital

-insula (layer is not visible at the hemisphere surface)

Frontal Lobe areas

A) prefrontal area

B) Primary motor cortex/ premotor cortex

c) Broca's area

Prefrontal area

- personality

- cognition ( thinking, learning and working memory)

- decision-making

Primary motor cortex/ premotor cortex

- precentral gyrus & anterior

- skeletal muscle control/ planning movements

Broca's area

motor area for verbal communication

Parietal Lobe

A) somatosensory and assoication areas

b) taste

Somatosensory and association areas

- postcentral gyrus

- interpreting touch, temp, pain sensations (skin)

Taste

- inferior postcentral gyrus

- interpreting / remembering tastes

Temporal Lobe

a) Long term memory formation

b) auditory and association area

c)  wernicke's area

d) olfactory and olfactory association area

e) emotions

Wernicke' area

word identification, comprehension and selection

amygdala

gray matter area inside

Occipital Lobe

vision and vision assocation areas

- striate cortex (map of retina)

- seperate assocation areas for color, motion, form

Insula Lobe

deep inside under lateral sulcus; functions such as memory, taste interpretation, language and balance

Cerebrum's Function Areas

1) Motor Area

2) Sensory Area

Motor Area of Cerebrum

"primary motor cortex"; control center located in frontal lobes; neurons control voluntary skeletal muscle activity w/ axons projecting contrallateraly

 Which lobe is the primary somatosensory cortex located?

Parietal lobes

Primary

Which lobe is the primary visual cortex located?

Occipital lobe

Which lobe is the primary auditory cortex located?

Temportal lobe

Which lobe is the gustatory (taste) cortex located?

Insula

Which lobe is the olfactory (smell) cortex located?

temporal lobe

White matter

lies deep to the gray matter of the cortex; occurs as tracts; contains clusters of gray matter called "cerebral nuclei"

White Matter Tracts in Cerebrum

- association tracts

- arculae fibers

- longitudinal fasciculi

- commisural tracts

- projection tracts

association tract

 connect seperate cortical areas of the same hemisphere

arcuate fibers

connect neighboring gyri within a single cerebral lobe

longitudinal fasciculi

 connect gyri between different cerebral lobes of the same hemisphere

commissural tracts

 connect corresponding lobes of right and left hemispheres

projection tracts

connect cerebral cortext to the diencephalon, braintem, cerebellum and spinal cord

Gray Matter

houses the motor neuron and interneuron cell bodies, dendrites, axon terminals and unmyelinated axons

Cortex

external sheets of gray matter that cover the surface of the most of the adult brain (cerebrum and cerebellum)

Areas of Gray matter

1) Basal forebrain nuclei

- memory, alertness

2) Basal ganglia

- habitual movements

- regulation of movements

Ventricles

fluid filled areas in brain connected with one another and the central canal of the spinal cord by ducts

Ventricles in Cerebrum?

2 Lateral ventricles

Ventricles Outside of cerebrum?

third and fourth ventricle

Interventricular foramen

lateral ventricle communicate with the 3rd ventricle

mesencephalic aqueduct

the 3rd ventricle communicates with the fourth ventricle

2) Diencephalon

2nd major region of brain; lies under lateral ventricles and around 3rd ventricle; "two headed"

3 components of the diencpehalon

epithalamus, thalamus, hypothalamus

Thalamus

two large oval masses; joined by intermediate commissure; 12 major nuclei; integrates, filters, and prioritizes all information going to cerebral cortex

Hypothalamus

- loated at the floor of 3rd ventricles, inferior and anterior to thalami; 12 nuclei; visceral control center

Epithalamus

 partially forms the posterior roof of the diencephalon and covers the 3rd ventricle

The epithalamus contains..

the pineal gland, pituitary gland and habenular nuclei

Pituitary gland

grape-like gland under hypothalamus; sits in sella turcica; part brain, part endocrine system; secretes many major hormones

Pineal gland

posterior to thalami; control of daily sleep/wake cycle via melatonin

Habenular nuclei

relay signals from the limbic system to the mesencephalon; involved in visceral and emotional responses to odors

3) Brain Stem

connects prosencephalon and cerebellum to the spinal cord; runs fromt he diencephalon to foramen magnum; outer is composed of white matter and inner is gray matter

3 parts of the Brain stem

mesencephalon, pons, medulla oblongata

Mesencephalon contains..

corpora quadrigemina, cerebral penducles, substantia nigra

Corpora Quadigremina

"body of 4 twins"; loaged poserior and supeireor; contains four heads (superior and inferior colliculi); known as auditory and visual reflexes

Cerebral penducles

anterior and inferior to corpora quadrgemina; motor tracts

Substantia nigra

internal to penducles; influences basal ganglia

Pons

anteior buldge; contains cranial nerves (5-7), projection tracts that run to/from cerebellum and auntonomic system; respiratory control centers

Medulla Oblongata

buldge under pons; all communcation between spinal cord and brain invovles the tracts ascending or descending through the medulla oblongata

Medulla Oblongata contains...

projection tracts to/from spinal cord; nuclei of 5 cranial nerves (8-12); reflex centers and control centers

4) Cerebellum

made up of gray matter layer, inner white layer, and deep gray matter layer

Arbor Vitae

white matter in the cerebellum

What are the functions of the cerebellum?

interprets proprioception siganls; coordinates voluntary muscle contractions; maintains posture

Peduncles

3 thick tracts that link the cerebellum with the brain stem; enables the cerebellum to "fine-tune" skeletal muscle movements

Superior Penducle

connects cerebellum to the mesencephalon

Middle Peduncle

connects the cerebellum to the pons

Inferior Peduncle

connects cerebellum to the medulla oblongata

3 layers of connective tissue

dura mater, arachnoid, pia mater

Dura mater

external layer; dense irregular connective tissue; partitions and anchors brain via the dural speta

2 layers of dura mater

1) outer periosteal sub-layer forms periosteum

2) inner meningeal sub-layer lines brain

Arachnoid

web-like middle layer; collagen and elastic fibers; contains subarachnoid space

Pia Mater

areolar connective tissue; lies on surface of brain following the contour of the brain