The brain and spinal cord
The brain and spinal cord make up the central nervous system (CNS). The CNS is made of different types of tissues and cells which can develop into different types of tumours.
To understand tumours of the CNS it helps to know about the:
- parts of the brain and spinal cord
- types of cells and tissues
What are the different parts of the brain and what do they do?
The brain controls everything we do and how our body functions.
It sends electrical messages along the spinal cord and the nerve fibres to all the parts of our body. The nerve fibres also bring electrical messages back to the brain. The different areas of the brain control the different parts of our body.
The largest part of the brain is called the cerebrum or forebrain. The cerebrum is divided into hemispheres: the left and the right hemisphere. The left hemisphere controls the right part of our body. And the right hemisphere controls the left part. Each hemisphere is further divided into 4 lobes.
The frontal lobe controls our speech, problem solving, movement, personality and sensations. The temporal lobe is where we process sounds and where our memories are stored. The parietal lobe is where touch, temperature and pain is processed. It is where we recognise objects and process information when people speak to us. The occipital lobe processes what we see.
At the back of the brain is the cerebellum or hindbrain. The cerebellum controls our balance, posture and coordination. The lower part of the brain is called the brainstem. It controls functions that we don’t usually think about such as breathing, sneezing, coughing, swallowing and our heartbeat.
In the middle of the brain are the pituitary gland and the pineal gland. The pituitary gland makes hormones that control lots of different body functions such as our growth and the production of sperm and eggs. The pineal gland makes the hormone melatonin which controls our sleep.
Around the brain we have a collection of bones called the skull and membranes called meninges. The meninges support and protect the brain. A clear fluid called cerebrospinal fluid runs between the meninges. The cerebrospinal fluid, or CSF, is made by tissue that lines the brain ventricles. The CSF flows in and around the brain and the spinal cord. It protects them from injuries and provides nutrients.
For more information about the brain, and cancers that affect the brain or spinal cord go to cruk.org/about-brain-tumours
The central nervous system (CNS)
The CNS is made up of the brain and the spinal cord.
The brain controls everything we do, from how we think to how we behave. It sends electrical messages to the rest of our body along nerve fibres.
The nerve fibres run out of the brain and join together to make up the spinal cord.
The spinal cord has bundles of long nerve fibres that carry signals to and from the brain, to all parts of the body. These long nerve fibres are called peripheral nerves.
The brain
The brain is protected by the skull. The main areas of the brain include the:
- cerebrum (also called the Forebrain)
- cerebellum (also called the Hindbrain)
- brainstem
The cerebrum
The cerebrum is the largest part of the brain and is divided into two halves, the right and left central hemispheres. Each half is divided into 4 areas (lobes):
- frontal lobe
- parietal lobe
- temporal lobe
- occipital lobe
The cerebrum is responsible for planned movement such as walking and talking. It is also responsible for our:
- thinking
- memory
- emotions
- senses
The frontal lobe is important for:
- speaking
- planning
- problem solving
- starting some movements
- processing emotions
- part of your personality and character
The temporal lobe is where you process sounds and where memories are stored. It is also responsible for processing language.
The parietal lobe recognises objects in the world and stores that knowledge. It's where you receive and process:
- touch
- pressure
- pain
This lobe processes what you can see.
The cerebellum
The cerebellum is at the back of the brain. It controls our balance and posture. It is also involved with timing and coordination of movement.
The brainstem
The brainstem is the lower part of the brain that connects with the spinal cord. It controls functions that we don't usually think about. They include:
- breathing
- sneezing and coughing
- swallowing
- our heartbeat and blood pressure
The main areas of the brainstem include:
- the midbrain - this connects the cerebrum with the lower part of the brain and the spinal cord
- the pons - which connects the cerebellum with the higher part of the brain and the spinal cord
- the medulla oblongata - which controls important functions such as breathing
The spinal cord
The spinal cord is a long bundle of nerves that stretch from the brain to the lower part of the back. It sends messages to and from the brain to the different parts of the body.
The spinal cord is protected by the bones of the spine. These are called vertebrae.
Meninges
Meninges are membranes that support and protect the brain and the spinal cord. A clear fluid called cerebrospinal fluid (CSF) travels in the spaces formed by the meninges.
The most common type of brain tumour that starts in the meninges is called meningioma.
Types of cells and tissues in the brain and spinal cord
The brain and the spinal cord are made up of different types of cells and tissues.
Glial cells are the supporting cells of the brain and the spinal cord. The most common type of brain tumours start in glial cells. These are called gliomas.
There are 3 types of glial cells:
- astrocytes – tumours that start in these cells are called astrocytoma or glioblastoma
- oligodendrocytes – tumours that start in these cells are called oligodendrogliomas
- ependymal cells – tumours that start in these cells are called ependymomas
Neurons are also called nerve cells. They are specialised cells that control everything we do. Our brain and spinal cord are made up of billions of neurons.
Brain tumours that start in the neurons are rare. They are often called neuronal tumours.
These are cells that are left over from the earliest development of the body in the womb. They can be found in different parts of the brain in children and young people. Usually these cells are harmless but rarely they become cancerous.
The most common type of brain tumours that start in neuroectodermal cells are medulloblastomas. They usually start in the back of the brain (cerebellum) and mainly affect children.
The brain and spinal cord are surrounded by a clear fluid called cerebrospinal fluid (CSF). It supports and protects the brain and the spinal cord.
Ventricles are spaces inside the brain filled with CSF. They connect with the space in the centre of the spinal cord and the brain membranes (meninges). So the fluid can circulate around and through the brain and spinal cord.
There are 4 ventricles inside the brain:
- two lateral ventricles – one on each side of the cerebrum
- the third ventricle
- the fourth ventricle
Some brain tumours can spread to the CSF. Doctors might take a sample of CSF from your lower back to help diagnose a brain tumour.
The pituitary gland makes hormones which are important for your body to function. These affect:
- growth
- the chemical processes that happen inside your body (your metabolism)
- periods and egg production in women
- sperm production in men
Different types of tumours can start in the pituitary gland.
The pineal gland is in the middle of the brain, just behind the brainstem. It makes a hormone called melatonin which controls your sleep patterns.
The blood brain barrier
The blood brain barrier is a natural filter between the blood and the brain which protects the brain from harmful substances.
This barrier stops some drugs from reaching the brain. This includes some types of chemotherapy drugs.
What next?
You might want to read about what brain tumours are.
