About Cerebellum and Brainstem

Finding the Best Care for a Loved One in a Coma

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This page continues our functional guide, to the areas of Cerebellum and Brain Stem. These lower brain structures not only control movement and the involuntary nervous system, but are more interrelated than once thought. While our charts give a localized view of the function of the brain, the more we learn from medical science, the clearer it becomes that the brain is a synergistic organ, where the all of its structures working together is key for even the most primitive functions.


Brain Structure  Function  Associated Signs and Symptoms 



Coordination and control of voluntary movement. 
  • Tremors.
  • Nystagmus (Involuntary movement of the eye).
  • Ataxia, lack of coordination. 
Brain Stem:     
  • Midbrain



Nerve pathway of cerebral hemispheres.

Auditory and Visual reflex centers.

Cranial Nerves:

  • CN III - Oculomotor (Related to eye movement), [motor].
  • CN IV - Trochlear (Superior oblique muscle of the eye which rotates the eye down and out), [motor]. 
    • Weber's: CN III palsy and ptosis (drooping) ipsalateral (same side of body).
    • Pupils:
    Size: Midposition to dilated. 
    Reactivity: Sluggish to fixed.
    • LOC (Loss of consciousness): Varies
    • Movement: Abnormal extensor ( muscle that extends a part).
    • Respiratory: Hyperventilating.
    • CN (Cranial Nerve) Deficits: CN III, CN IV.
    • Pons 


    Respiratory Center.

    Cranial Nerves:

  • CN V - Trigeminal (Skin of face, tongue, teeth; muscle of mastication), [motor and sensory].
  • CN VI - Abducens (Lateral rectus muscle of eye which rotates eye outward), [motor].
  • CN VII - Facial (Muscles of expression), [motor and sensory].
  • CN VIII - Acoustic (Internal auditory passage), [sensory]. 
    • Pupils:
    Size: Pinpoint
    • LOC:
    "Akinetic Mute".
    "Locked In" Syndrome.
    •  Movement:
    Abnormal extensor.
    • Respiratory:
    Apneustic (Abnormal respiration marked by sustained inhalation).
    • CN Deficits: CN VI, CN VII.
    • Medulla  Oblongata


    Crossing of motor tracts.

    Cardiac Center.

    Respiratory Center.

    Vasomotor (nerves having muscular control of the blood vessel walls) Center 

    Centers for cough, gag, swallow, and vomit.

    Cranial Nerves:

  • CN IX - Glossopharyneal (Muscles and mucous membranes of pharynx, the constricted openings from the mouth and the oral pharynx and the posterior third of tongue.), [mixed].
  • CN X - Vagus (Pharynx, larynx, heart, lungs, stomach), [mixed].
  • CN XI - Accessory (Rotation of the head and shoulder), [motor].
  • CN XII - Hypoglossal (Intrinsic muscles of the tongue), [motor].
    • Movement: Ipsilateral (same side) plegia (paralysis).
    • Pupils:
    Size: Dilated.
    Reactivity: Fixed.
    • LOC: Comatose.
    • Respiratory:
    Abnormal breathing patterns.
    • CN Palsies (Inability to control movement):
    Absent Cough.

    Get Help

    Finding the Best Care for a Loved One in a Coma 

    Return To Previous Page

    Return To Brain Anatomy

    Intracranial Pressure

    Understanding Coma

    Rancho Los Amigos Scale/ The Levels of Coma

    Objectives of Neurosurgery

    A Glossary of Terms  


    Attorney Gordon S. Johnson, Jr.

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