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Chapter Two

The Anatomy and Evolution

of the Nervous System

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CHAPTER 2THE ANATOMY AND EVOLUTION OF THE

NERVOUS SYSTEM

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Anatomical Directions

• Rostral or anterior – Head end of four legged animal

• Caudal or posterior

 – Tail end of four legged animal

• Inferior or ventral

 – Towards the belly

• Superior or dorsal

 – Towards the back

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lanes of Section

• Coronal !frontal"

• Sagittal

• Hori#ontal !a$ial"

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%igure &'( Anatomical Directions

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%igure &'& lanes of Section

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rotecting and Supplying the )ervousSystem

• *eninges – Three layers of meninges provide protection

• Cerebrospinal %luid – Secreted in hollow spaces in the brain known as

ventricles

 – Circulates through ventricles+ subarachnoidspace+ and central canal of the spinal cord

• ,lood Supply – ,rain receives nutrients through the carotid

arteries and vertebral arteries

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%igure &'- The Skull and Three .ayersof *embrane rotect the ,rain

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%igure &'/ Cerebrospinal %luidCirculates Through the 0entricles+

Spinal Cord and Subarachnoid Space

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%igure &'1 The ,rain Has a 2enerousSupply of ,lood

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%igure &'3 The 4rgani#ation of the)ervous System

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 The Central )ervous System

•  The Spinal Cord – 5$tends from medulla to the 6rst lumbar vertebra

•  The Hindbrain – The myelencephalon !medulla"

 – The metencephalon !pons and cerebellum"

•  The *idbrain – The mesencephalon

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%igure &'7 The Anatomy of the SpinalCord

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%igure &'(8 Structures of the ,rainStem

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 Table &'( Some Important Structures ofthe ,rainstem

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%igure &'(( The Internal Structure ofthe *idbrain

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 The Central )ervous System

•  The %orebrain – The Thalamus and Hypothalamus of the

Diencephalon

 – The ,asal 2anglia – The .imbic System

 – The Corte$• .obes of the corte$

• .ocali#ation of function in the corte$

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%igure &'(& The Thalamus andHypothalamus of the Diencephalon

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%igure &'(- The ,asal 2anglia Are.ocated Deep 9ithin the Cerebral

Hemispheres

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%igure &'(: The .imbic Systemarticipates in .earning and 5motion

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 Table &'& Structures of The .imbicSystem

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%igure &'(; Comparative Convolutionsof the Corte$

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%igure &'(1 The .ayers of the CerebralCorte$

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%igure &'(7 The .obes of the CerebralCorte$

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%igure &'&8 The Corpus Callosum andthe Anterior Commissure

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 The eripheral )ervous System

•  The Cranial )erves – 5nter and e$it the brain directly to serve the region of

the head and neck

•  The Spinal )erves

 – -( pairs of spinal nerves e$it the spinal cord to providesensory and motor pathways to the torso+ arms+ andlegs

 – *i$ed nerve !containing an a

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%igure &'&& The (& airs of Cranial)erves

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%igure &'&- The Structure of the SpinalCord

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 The Autonomic )ervous System

•  The Sympathetic )ervous System – %ight=or=>ight system

•  The arasympathetic )ervousSystem – rovides rest+ repair+ and energy storage

• Central Control of the Autonomic

)ervous System – Hypothalamus+ midbrain tegmentum+ and

reticular formation

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%igure &'&: The Autonomic )ervousSystem

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 The 5volution of the Human ,rain and)ervous System

• )atural Selection and 5volution – )atural selection favors the organism with highest

degree of 6tness

• 5volution of the )ervous System – %airly recent development

 – 0ertebrates or chordates ? animals with spinalcolumns and real brains

• 5volution of the Human ,rain – 4utstanding feature of modern humans is brain

si#e

 – ,rain development occurred very @uickly

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%igure &'&/ Timeline for the 5volutionof the ,rain

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%igure &'&; True ,rains Are %ound inChordates

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%igure &'&1 Chordate ,rains Continuedto 5volve