The Brain and Cranial NervesPg. 129

Three Main Regions of the Brain

• Forebrain– Cerbral hemispheres– Diencephalon

• Midbrain– Brain stem

• Hindbrain– Pons– Cerebellum– Medulla oblongata

Forebrain

• Interprets sensory inputs

• Controls voluntary and skilled muscle

• Functions in intellectual and emotional processing

Cerebral Hemispheres Left & Right

• Grey Matter – Cell bodies of neurons• White Matter – Fiber Tracts of neurons• Gyrus –Elevated Ridges

– Ex. Precentral Gyrus – Primary Motor Area

• Sulcus – Shallow Grooves• Fissures – Deep Groves

– Longitudinal Fissure – Separates Hemispheres

Cerebral Hemispheres Left & Right

• FRONTAL LOBE :ThinkingPlanningPersonalityEmotions

• TEMPORAL LOBE :Understanding speechMemoryHearing

• PARIETAL LOBE :Face MovementsDrawingFeeling and touch

• OCCIPITAL LOBE :Vision

Cerebral Hemispheres Left & Right

• Frontal Lobe– Precentral Gyrus –

Primary Motor Area– Learned Motor Skills– Sense of Smell– Prefrontal Cortex –

intellect, complex learning, recall, personality

Cerebral Hemispheres Left & Right

• Parietal Lobe– Primary

Somatosensory Cortex, receives input from sensory inputs

– Integrate different sensory inputs (temp., pressure, etc)

– Perception Taste

Cerebral Hemispheres Left & Right

• Temporal Lobe– Conscious Awareness

of balance– Auditory– Language areas-

• Wernicke’s

Cerebral Hemispheres Left & Right

• Occipital Lobe– Visual association area– Primary Visual Cortex

Cerebral Hemispheres

• Many similar functions in both cerebral hemispheres – motor and sensory areas

• However, each hemisphere is a “specialist”– Left Hemisphere – “Language brain”

• Language and Speech skills

– Right Hemisphere – Abstract, conceptual or spatial processes

• Artistic or creative pursuits

Cerebral Hemispheres

• Additional features to Identify:– Corpus Callosum

• Connects two hemispheres of cerebral cortex

– Fornix• Involved in smell

– Septum pellucidum• Separates lateral ventricles of cerebral hemisphere

Diencephalon

• “Most superior portion of the Brain Stem”• Be able to Identify:

– Olfactory Bulbs and Tract– Optic Nerves & Chiasma– Pituitary Gland – Hypothalmus

Diencephalon

• Thalmus– Memory processing– Senory impulse to cerebral

cortex for processing

• Hypothalmus– intergrates involuntary

nervous system– Regulates body

temperature, food intake, water balance, thirst and biological rhythms

– Regulates hormones

Midbrain (Brainstem)

• Functions in conducting pathways between higher and lower brain centers

Cerebellum

• Composed of Two Hemisphere– Connected by Vermis

• Composed of Grey & White matter• Involved in unconscious coordination of

skeletal muscle• Provides “instruction” to cerebral motor

cortex that aid in control of balance & equilibrium

Cerebellum

• Be able to identify:– Vermis– Arbor Vitae

• “Tree of Life” – White Matter

– Coroporaquadrigemina

• Involved in visual and auditory relfexes

Meninges

• Covers and protects Brain • 3 layers:

– Dura Mater• Composed of 2 layers

– Arachnoid Mater– Pia mater

Meningitis

• Inflammation of meninges• If spreads to neural tissue may cause

encephalitis• Diagnosed by taking sample of

Cerebrospinal Fluid

Ventricles

• Circulate cerebrospinal fluid– Provides cushion to brain

and spinal chord– Reduces brainweight by

97% prevents crushing under its own weight

• 4 total:– Lateral– Third– Cerbral Aqueduct– Fourth

Now we look at Brains!

Cranial Nerves

• 12 total• Know their name and number• Know their functions• “On Occasion Our Trusty Truck Acts

Funny, Very Good Vehicle AnyHow”

3 Purely Sensory

• I. Olfactory– Sense of Smell

3 Purely Sensory

• I. Olfactory• II. Optic

– Sense of Sight

3 Purely Sensory

• I. Olfactory• II. Optic• VIII. Vestibulocochlear

– Sense of Hearing

4 Associated with the Eye

• II. Optic• III. Oculomotor• IV. Trochlear• VI. Abducens

…And the rest…

• V. Trigeminal– Major Sensory nerve

of face

…And the rest…

• V. Trigeminal• VII. Facial

– Motor fibers to muscles of facial expression

– Sensory from anterior portion of tongue

…And the rest…

• V. Trigeminal• VII. Facial• IX. Glossopharyngeal

– Sensroy fibers to pharynx, tonsils, and posterior tongue

– Pharyngeal muscles

…And the rest…

• V. Trigeminal• VII. Facial• IX. Glossopharyngeal• X. Vagus

– Motor fibers for heart and smooth muscles of abdomen

…And the rest…

• V. Trigeminal• VII. Facial• IX. Glossopharyngeal• X. Vagus• XI. Accessory

– Muscles associated with chewing

…And the rest…

• V. Trigeminal• VII. Facial• IX. Glossopharyngeal• X. Vagus• XI. Accessory• XII. Hypoglossal

– Motor fibers to muscles of tongue

Now we dissect sheep brains!!