the brain & cranial nerves structure & funtion. the brain –introduction –development of...

The Brain & Cranial Nerves

Structure & Funtion

The Brain

– Introduction

– Development of brain

– Anatomy of brain• Parts and

functions

Introduction to the Brain

– Weighs about 3 lbs. in adults

– Structures• Divided into 3 general areas

– Functions• Controls the bare necessities of life• Location for primal drives and emotions• Intellectual thought, imagination, perception,

interpretation, etc.

Human Anatomy, 3rd editionPrentice Hall, © 2001

Adult Brain

– Forebrain

• Cerebrum• Thalamus &

hypothalamus

– Midbrain

– Hindbrain • Cerebellum

& pons• Medulla oblongata


Protections and Coverings

– Cranial bones – Meninges – 3 Part Structure

• Dura mater– Tough Outside

• Arachnoid– Form Web-like

Spaces

• Pia mater– Flexible Inner

Layer


The Ventricles of the Brain– Hollow areas within the brain

• Connect to spinal canal and space around the brain


Ventricles of the Brain


Cerebrospinal Fluid

– Choroid Plexus- Filters CSF form blood– Composition

• Clear, colorless, watery• Contains proteins, glucose, urea, salts• Contains white blood cells

– Functions• “Floats” the brain• Medium of transport

– Formed by specialized cells along edges of ventricles


Circulation of Cerebrospinal Fluid

– Cerebrospinal fluid circulates around the brain, down through the ventricles, and into the spinal cord.


Problems Associated with CSF

– Disorders• Hydrocephalus• Meningitis• Headaches• Concussions

– Treatments• Lumbar Puncture• Hormone Treatment• CFS Catheter & Stints


Blood-Brain Barrier

– A function of glial cells • Secrete chemicals that

maintain the BBB• Absorb materials from

blood• Extract materials from

brain

– Cells of capillaries form tight junctions

– Differential rates of passage of certain materials


The Parts of the Brain

ForebrainCerebrum, Hypothalamus, Thalamus


Cerebrum – Gray & White Matter

– Outer layer• Cerebral cortex

– Gray matter– Functional

Portion

– Inner portion• White matter• Cerebral nuclei

– Masses of gray matter


Cerebral Cortex

– Gyri are separated by grooves (sulci)• Fissures – deeper

grooves

– Divided into cerebral hemispheres

– Connected by the Corpus Callosum


Cerebral Cortex

– Divided into lobes

– Well mapped• Decision-making,

planning, personality

• Primary motor cortex

• Primary sensory cortex

Homunculus

Primary Motor Cortex

Primary Sensory Cortex


Cerebral Nuclei

– Collections of cell bodies (gray matter)

– Mostly control the movement of skeletal muscles


Limbic System

– Functional unit– Emotional part of

the brain• Feelings of fear,

loss, love, rage, etc.

– Includes parts of several anatomical structures• Cerebrum• Hypothalamus• Thalamus


Hypothalamus

– Location – under thalamus

– Structure• Clusters of nerve cell

bodies– Autonomic centers

• Infundibulum

Hypothalamus

– Secretes Hormones- ADH

– Initiates primal drives • Hunger, thirst, sex, rage, etc. • Controls autonomic nervous system

– “fight or flight” sympathetic response

– Helps control pituitary gland (“master gland” of endocrine system)• Infundibulum (“funnel”) funnels secretions

to the pituitary gland


Thalamus

– Functions as a relay station between the body and the cerebral cortex

• Inform us of our emotional state

• Relay information concerned with motor requirements & actions

• Integrate visual and auditory reflexes

• Parasympathetic

response


Epithalamus

– Location• Above

thalamus

– Contains the pineal body• Secretes

melatonin (circadian rhythm)


Midbrain


Midbrain – Relay station– Tracts of motor and

sensory neurons– Contains nuclei

• Substantia nigra secretes dopamine (what’s this?)

– Modifies muscle tone & motor activity

– Parkinson’s disease & drugs


Hindbrain

Cerebellum, Pons, & Medulla Oblongata


Cerebellum– 2nd largest structure of

the brain– Divided into 2 lateral

hemispheres– Cortex – gyri & sulci

• Gray matter

– Interior• White matter

– Cerebellar nuclei – deep within white matter

• Gray matter

Cerebellum

– Functions – controls subconscious movements in skeletal muscle• Coordination• Posture• Balance


Pons

– Pons = “bridge”• Connects the spinal

cord with the brain and parts of the brain with each other

• Consists mostly of white fibers

– Functions• Controls

respiration rate (with medulla)


Medulla Oblongata

– Continuation of spinal cord

– Functions• Maintains

wakefulness and alertness

• Contains reflex centers

– Cardiac center, vasomotor center, respiratory rythmicity center


Cranial Nerves


Introduction to Cranial Nerves

– 12 pairs– Leave the skull

through foramina– Types

• Mixed

• Sensory

• Motor

– Part of the somatic nervous system

– Innervate organs in head, neck and upper thorax

the brain & cranial nerves structure & funtion. the brain –introduction –development of...

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