Learning the Brain: Neuroanatomy Basics for Understanding Hydrocephalus

What are the main parts of the brain?  

Let’s take a look at how your brain is constructed. There are a lot of different areas that can be affected by hydrocephalus. The anatomy of the brain as well as the impairments one may experience when that area is affected by hydrocephalus are highlighted here.   

To start, your brain is divided up into 4 main areas: the cerebrum, diencephalon, cerebellum, and brainstem.  

• The cerebrum consists of the brain’s lobes: frontal, temporal, parietal, and occipital

• • Frontal lobe: responsible for thinking, planning and organizing, and problem-solving.
    • People with frontal lobe dysfunction may struggle with tasks that involve decision-making or multi-tasking.   

• • Parietal lobe: helps process the sensations we receive from our environment such as taste, temperature, and texture.
    • Parietal lobe injury can result in sensory processing issues (problems with touch, pain, temperature, or pressure), difficulty with navigation or following directions, or challenges with reading, writing, or math.

• • Occipital lobe: processes images from your eyes and connects them to images that are stored in your memory; allows for recognition of images.
    • Damage to the occipital lobe can manifest in vision difficulties or difficulty recognizing faces or objects. 

• • Temporal lobes: mediator lobes that help process senses (taste, smell, sound) and help with memory storage.
    • When the temporal lobe is affected, a patient may have difficulty with language comprehension, memory problems, or changes in perception and behavior. 

• The diencephalon, or your inner brain, sits underneath the cerebrum and helps control your emotions and memories. Your inner brain is composed of 3 main structures:
  • Thalamus: acts as a message board or gatekeeper for all signals passed between the brainstem and cerebrum
    • Patients with damage to the thalamus might experience symptoms affecting sensation (feeling tingling, numbness, pain), movement (trouble walking or body tremors), speech, or sleep (too much or too little).  
  • Hypothalamus: the main emotional control area; also helps regulate your body’s ‘instinctive’ actions such as eating and sleeping
    • Due to its homeostatic (regulatory) nature, alterations to the hypothalamus can cause a variety of symptoms from metabolic (struggling to control weight, appetite, temperature, or heart rate), hormonal (problems with growth, fertility, mood), neurological (excessive headaches, problems with vision), and behavioral (displaying untoward aggression or defiance).  
  • Hippocampus: sends your memories to other areas of the cerebrum, where they can be stored and retrieved later
    • Damage to the hippocampus can cause people to have trouble recalling short-term memories, have difficulty recalling past events, or getting lost in places that are familiar to them.  

• The cerebellum and brainstem are primitive areas of the brain that are responsible for our survival: 
  • The cerebellum: or “mini brain”, sits outside and underneath the cerebrum. The cerebellum is responsible for coordinating movement while receiving information from your muscles, eyes, and ears. Complex movements such as throwing a baseball or playing piano require lots of input to and from the cerebellum.
    • Because of the cerebellum’s role in movement and coordination, these abilities might be affected if the cerebellum is injured. One might struggle with gait (walking straight, balancing), tremors, and rapid alternating movements (doing multiple movements in quick succession such as tapping the feet on the ground or touching your fingers together).  
  • The brainstem: is the upper part of the spinal cord that connects directly to the cerebellum and cerebrum. The brainstem is responsible for functions that are essential to life, such as blood pressure, heart rate, and breathing.
    • Injuries affecting the brainstem can manifest as having difficulty balancing, struggling with breathing and swallowing, or even losing consciousness.

Where are the ventricles? 

Now that we have an idea of what’s going on in different parts of the brain, we can see where the brain’s ventricles are located and how they relate. The brain has 4 main ventricles that are present in different parts of the brain: 

• Lateral ventricles: 2 identical ventricles located within the cerebrum with one ventricle on each side of the brain
• Third ventricle: located in the diencephalon (inner brain) and sits right next to the thalamus
• Fourth ventricle: located in the hindbrain, a specific area of the brainstem 

All the ventricles are connected and act as one unit. The ventricles also contain the choroid plexus, the tissue that is responsible for creating cerebrospinal fluid (CSF). Read more about the choroid plexus and its role in hydrocephalus here.  

In hydrocephalus, the ventricles accumulate a lot of extra fluid. This causes them to expand inside the brain and compress areas of the brain against the skull, possibly causing injury to that brain area. 

What happens to the brain in hydrocephalus? 

During hydrocephalus, there is an expansion of the ventricles due to an excessive amount of CSF. When the ventricles expand, they push the brain up against the skull. Each person is different, and where the ventricles are enlarged can determine what parts of the brain are affected. This is why the symptoms in those with hydrocephalus vary and can include: 

• Nausea and vomiting
• Headaches
• Vision issues
• Developmental delays
• Balance and coordination issues
• Short-term memory loss
• Forgetfulness
• Incontinence

Conclusion 

Increased pressure on different regions of the brain may result in a wide range of outcomes, which could explain why symptoms vary so widely from person to person. Thus, understanding how hydrocephalus affects different areas of the brain is essential—not just for treatment, but also for gaining a clearer picture of the full impact of the condition. This is why funding research into the causes and effects of hydrocephalus is so critical. 

Recognizing the variability in both symptoms and outcomes among individuals with hydrocephalus also highlights the importance of focusing on neuropsychology and cognition in hydrocephalus care, which is one of our key Research Priorities. Seeing a neuropsychologist can help individuals and families better understand how hydrocephalus impacts memory, attention, behavior, and more. For more on this, check out our blog on understanding cognitive function in hydrocephalus.