Central Nervous System

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Central Nervous System
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Divisions of the Brain

• Brainstem
• Medulla oblongata
• extension of spinal cord
• Contains the cardiac, respiratory and vasomotor
  centers (control heartbeat, blood vessel
  diameter)
• Consists of white and gray matter intermingled
• Pons
• Midbrain

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Diencephalon

• Small, located above midbrain, below cerebrum
• Consists of 2 major structures hypothalmus and
  thalmus
• Hypothamus
• Pituitary gland is an extension of hypothalmus
• Major control over most major organs
• Make hormones secreted by pituitary gland
• Secrete releasing hormones into blood to the
  anterior pituitary gland
• Helps regulate water balance, body temperature,
  sleep cycles and appetite and many emotions

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Diencephalon

• Thalmus
• Dumb bell shaped gray matter, above hypothalmus
• Axons go into cerebellum
• Helps produce sensations, associates sensations
  with emotions and plays a role in the arousal or
  alerting mechanism

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Cerebellum

• Second largest part of human brain
• Arbor vitae tree of life, gray matter on
  outside, white matter inside
• Produce smooth, coordinated movements, maintain
  equilibrium and sustain normal postures.

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cerebrum

• Largest and upper most part of brain
• Ridges convolutions or gyri
• Grooves sulci, deep grooves fissures
• Longitudinal fissure divides into left and
  right
• Find also the central sulcus, lateral fissure
• Corpus callosum connects left and right
  hemisphere of the brain

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cerebrum

• 4 major lobes of the brain named for bones
• Frontal, Occipital, Temporal, parietal
• Cerebral cortex gray matter, surface of
  cerebrum
• White matter (tracts) makes up most of cerebrum
• exception is basal ganglia (produce automatic
  movements and posture, ex. Parkinson disease

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Brain disorders

• Cerebrovascular accident (CVA) stroke
  hemorrhage or cessation of blood flow through
  vessels in brain, neurons die
• If damage occurs in a motor control section of
  brain, movement ceases
• Cerebral palsy damage to brain tissue
• Prenatal infections, trauma to the head before,
  during, after birth, reduced oxygen to brain
• Spastic paralysis involuntary contractions of
  affected muscles
• Hemiplegia 1 side of body
• Paraplegia both legs
• Triplegia both legs, 1 arm
• Quadriplegia all 4 appendages

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Degenerative brain disorders

• Destruction of neurons in the brain
• Affects memory, attention span, intellectual
  capacity, personality and motor control
  dementia
• Alzheimer Disease (AD) lesions on cerebral
  cortex
• Huntington disease (HD) chorea involutary
  purposeless movements

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Seizure

• Seizure sudden bursts of abnormal neuron
  activity
• Range from mild to severe
• Epilepsy recurring or chronic seizures
• Can be caused by tumors, trauma, or chemical
  imbalances, most idiopathic
• Medications block neurotransmitters in affected
  areas of the brain.

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Spinal cord

• Average of 17 18 inches
• From occipital bone to L1 vertebrae
• core is made up of gray matter
• Outer part is white matter spinal tracts

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Spinal cord

• 2 way conduction
• Ascending tracts to brain
• Descending tracts from the brain
• Primary reflex center
• Cut in the spinal cord results in no
  communication
• Anesthesia loss of sensation
• Paralysis loss of the ability to make voluntary
  movements

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Coverings

• Meninges touch, fluid-containing membrane
• 3 layers
• Dura mater tough outer layer
• Pia mater innermost membrane, covers spinal
  cord
• Arachnoid mater between dura and pia mater, cob
  web like
• Meningitis infection or inflammation of meninges

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Fluids

• Cerebrospinal fluid (CSF) fills subarachnoid
  spaces in brain and spinal cord and ventricles in
  brain
• 2 lateral ventricles and third ventricle
• CSF is continuously begin made from fluid
  filtering out of choroid plexus and into
  ventricles and continues to circulate around the
  brain and spinal cord
• Hydrocephalus water on the brain accumulation
  of CSF in ventricles