17 brain stm & maj nervy path

ression

medulla oblongata

LOCO
• Inferior most portion of brainstem
• At level of Foramen Magnum

Major structures:
• Cardiovascular &Respiratory Centers
• Motor &Sensory Decussation (cross over)
• Cranial nerves

pons

• superior to medulla

• bridge to cerebellum

• contain major respiratory centers

  • cranial nerves

mid brain

superior to pons

auditory and visual reflex center

auditory stimulation = turn eyes toward sound

diencephalon

thalamus AND hypothalamus

superior to brainstem

direct relay center for all sences BUT smell

directs sensory to appropiate place in cortex

hypothalamus

Location:
• Superior to Midbrain
• Inferior to thalamus

• Contents: Multiple Nuclei (colored portions)
• Control sleep & wake cycle
• Hunger/thirst
• Temperature

• Controls Autonomic NS along with Pituitary
Gland – located beneath hypothalamus

Homeostasis

reticular formation

Column of neurons located in middle of brain stem
• From medulla to thalamus
• These neurons maintain a conscious state
• When damaged, coma may result

cerebellum

coordinates movements - DOES NOT INIATIATE THEM

basal ganglia

• movement planning

• iniate movement in an adult

  • control movement in babies

substantia nigra

• motor function

  • when damaged = parkinsons

midbrain

limbic system

formed by many parts of brain (amygdala and hippocampus)

many functions = sex drive, memory, emotion, fear

sensory pathway

1. origin sensory nerves

2. pathway - up spinal cord

3. decussation = cross to opp side medulla

   1. desination = brodmann areas 3 1 2 somoatosensory cortex

dorsal comumn medial leminsicus pathway

• fine touch and proprioception

• 2 bundles in posterior spinal cord

• cuneatus = upper body

• gracilis = lower body

corticospinal tract = ventral motor pathway

cortex to spinal cord

1. origin = brodmann area motor cortex

2. decussation = cross at meddulla

3. travel down spinal cord

4. on to skeletal mucles

upper motor neuron

Starts in brain, ends in spinal cord
• Cell body located in gray matter of cortex (precentral gyrus)
• Its axon synapses on a Lower Motor Neuron

lower motor neuron

• Starts in spinal cord and ends in muscle
• Cell body is in ventral grey horn in brain stem or spinal cord.
• Its axon synapses on skeletal muscle Fibers
• AKA peripheral motor nerve

Poliomyelitis

lower motor neuron disease
• Flaccid Paralysis
• Reflexes Absent
• Muscles Atrophy

stroke

upper motor neuron lesion

cerebrovascular accident

Blockage/rupture of cerebral arteries
• No blood to brain (Ischemia)
• Result: lesion - dead of neurons
• Result: Region of dead brain

babinski

Upper motor neuron lesion

normally keeps sensory impulse from spreading to other nerve roots
• Normal stimulation of plantar foot:
• In baby, hallux extends, other digits fan out
• In adult, all toes curl and adduct

If damage to upper motor neuron in adult, has same response as infant
• Upper motor neuron not containing spread of impulses
• Reflex spreads to extensors instead of flexors

cranial bleeds

ruptured blood vessel

• blood fills spaces between meninges

• pressure builds and damages brain

cuneatus

upper body

grailis

lower body

ischema

no blood 2 brain