Central Nervous System

Basic Brain Anatomy

• Male brains larger than female brains• Male = 1600 grams Female = 1450 grams• Consists of three major parts:• Cerebrum• Cerebellum• Brain Stem• Covered by tough sac called the “dura mater”• Includes sensory areas, motor areas, association

areas

Cerebrum

• Divided into cerebral hemispheres (left, right)• Form about 83% of brain mass• Appears “wrinkled”• Gyri = elevated ridges of tissue• Sulci = grooves between ridges• Central sulcus splits anterior/posterior portions of cerebrum• Wrinkled tissue greatly increases surface area• Deeper grooves called “fissures”• Longitudinal fissure separates left, right hemispheres• Transverse fissure separates cerebrum from cerebellum

Cerebral Cortex

• “Executive suite” of the nervous system• Allows us to experience LIFE!!!• Allows us to experience conscious behavior• Gray in color (gray matter)• Consists of neuron cell bodies, dendrites,

unmyelinated axons plus glial cells• Only 1/8” thick but ……..• Wrinkled anatomy & surface area = 40% of

brain’s mass!!

Sensory Areas

• Afferent division• Strip of tissue located posteriorly to central sulcus

• Primary somatosensory cortex• Receives information • Spatial discrimination• Receives senses from sensitive areas e.g. lips/fingertips/genitals

• Somatosensory association area• Analyzes temperature, pressure, etc• Can tell what an object is just by touch

• Visual cortex - vision. Visual association area - sight recognition• Gustatory cortex - taste. Olfactory cortex - smell

Motor Areas

• Located anterior to central sulcus• Primary motor cortex - voluntary muscle

movement• Premotor cortex - skills of a repetetive

nature• Juggling• Typing• Dribbling a basketball• Walking

Misc. Brain Regions ….

Broca’s Area

• Motor/speech area• Controls movement of lips along with

sound to form speech

Prefrontal Cortex

• Most complicated of all brain regions!!

• Why?• Responsible for memory, conscience

Freud’s Personality Divisions

• Id - driven by pleasure!!! Instinct…• Ego - Reality component of personality.

Tries to balance id and superego. Organized and realistic.

• “How do I make this work??”• Superego - morality. “Inner voice”

Thalamus

• Plays a key role in mediating:• Sensation• Motor activities• Learning• memory

Hypothalamus

• Visceral control center of the body• Controls involuntary body functions• Center for emotional response & behavior• Body temperature regulation• Regulates food intake• Regulates water balance/thirst• Regulates sleep/wake cycles• Controls endocrine system functioning• Pleasure center

Amygdala

• Plays a role in controlling anxiety• Works with hypothalamus• Responsible for anger & fear

Midbrain

• Pain suppression• Visual reflex centers • Coordinates head/eye movements

Pons

• Controls rhythm of breathing

Medulla Oblongata

• Respiratory center• Vomiting• Hiccups• Swallowing• Coughing

Lateralization of Cortical Functioning

• Division of labor in the cerebrum• Left hemisphere controls right side of body & vice versa• In 90% of people: • Left side of brain = language, analytical, mathematics, logic• Right side of brain = visual/spatial skills, appreciation of

music/arts, emotion, creativity, etc• “right-handed”• The other 10 % of people:• “left-handed” or ambidextrous• Roles reversed on each side• Brain hemispheres connected by corpus callosum

Cerebellum

• 11% of brain mass• Provides for timing/patterns of skeletal muscle

contraction• Responsible for smooth, coordinated movements• Driving, typing, playing musical instruments, etc• Functioning occurs subconsciously; we are not

aware of it