The brain – structure
and function
This information is an extract from the booklet Understanding
brain tumours. You may find the full booklet helpful. We can
send you a copy free – see page 5.
Contents
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•
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Introduction
Main structures and functions of the brain
Types of brain cells
Primary and secondary brain tumours
Introduction
The brain and the spinal cord make up the central nervous
system (CNS). This is the ‘control centre’ that coordinates the
body’s functions.
The brain is contained within the skull, which protects it.
Between the brain and the skull there are three layers of
membrane called the meninges (see diagram on page 2).
These completely cover the brain and spinal cord and help
to protect it. Between two of these layers is a space called
the subarachnoid space. This space contains a fluid called
cerebrospinal fluid (CSF).
Main structures and functions of the brain
The main parts of the brain are:
•the cerebrum (the forebrain)
•the cerebellum (the hindbrain)
•the brain stem.
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The brain – structure and function
Cerebrum (see diagram below)
This is the largest area of the brain and controls all higher
mental functions, such as thinking and memory. It’s made up of two halves, or hemispheres. The right cerebral
hemisphere controls the left side of the body, and the left
cerebral hemisphere controls the right side of the body.
Bone
Subarachnoid
space
Brain
Dura mater (outer layer)
Arachnoid (middle layer)
Pia mater (inner layer)
Meninges
Cerebrum
Bone
Pituitary gland
Cerebellum
Brain stem
Spinal cord
The brain
Each cerebral hemisphere is divided into four areas, known as lobes:
Frontal lobe (see diagram opposite) – controls thought,
memory, planning, problem solving and behaviour.
Parietal lobe – is responsible for language, helping us
form words and thoughts. It also deals with touch and how we recognise sensations, and helps us be aware of our body position. Temporal lobe – helps us understand and process what
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The brain – structure and function
we hear. It’s also involved with how we learn and organise
information.The temporal lobe is also responsible for emotions
and emotional memory.
Occipital lobe – is where all visual information is processed,
such as colour, shape and distance.
Cerebellum
This is the back part of the brain and is concerned with
balance and coordination. These activities are carried out
automatically (subconsciously) by this area of the brain and are not under a person’s control.
Brain stem
This controls the basic functions that are essential for
maintaining life, including breathing, body temperature, heart rate and blood pressure. It also controls eye movements
and swallowing. It’s a very sensitive and important part of the brain, and it connects the cerebral hemispheres to the spinal cord.
Language
and touch
Thought,
memory and
behaviour
Visual
processing
Hearing, learning
and emotions
Balance and
coordination
Breathing,
heart rate and
temperature
The lobes and functions of the brain
PARTS OF THE BRAIN
Frontal lobe
Parietal lobe
Temporal lobe
Occipital lobe
Cerebellum
Brain stem
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The brain – structure and function
Pituitary gland
Just below the base of the brain is the pituitary gland. This is a
small gland that makes lots of different hormones that control
and regulate the other hormone-producing glands of the body.
Types of brain cells
Like every other organ in the body, the brain is made up of
cells. There are about 40 billion nerve cells, called neurones,
within the brain. Everyone is born with a similar amount. Unlike other cells, nerve cells can’t replace themselves. In fact,
as we get older there is a gradual decrease in their number.
Nerve cells communicate with each other, and other parts of
the body, by sending messages (nerve impulses) through a
system of nerve pathways or networks.
Nerve cells are held in place and supported by cells called
glial cells. There are different types of glial cells, including
astrocytes, oligodendrocytes and ependymal cells.
Primary and secondary brain tumours
Primary brain tumours
Primary brain tumours are tumours that start in the brain and have not spread there from somewhere else in the body.
Benign brain tumours remain in the part of the brain where
they started, and don’t spread into and destroy other areas of
the brain. They don’t spread to other parts of the body.
If a benign brain tumour can be removed successfully it
shouldn’t cause any further problems. However, sometimes
it‘s difficult to remove the tumour because of its position within
the brain, or because the surrounding brain tissue could be
damaged by surgery. Some benign tumours will regrow slowly
and, if this happens, treatment with radiotherapy or further
surgery may be needed.
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The brain – structure and function
Malignant primary brain tumours are most likely to cause
problems by spreading into the normal brain tissue around
them, causing pressure and damage to the surrounding areas
of the brain. These tumours rarely spread outside the brain to
other parts of the body.
Secondary brain tumours
A secondary brain tumour is a cancer that has spread to the brain from another part of the body.
Your doctor will be able to tell you if your brain tumour is
a primary or secondary tumour. We have a fact sheet and
information on our website about secondary brain tumours.
More information and support
Cancer is the toughest fight most of us will ever face. But you
don’t have to go through it alone. The Macmillan team is
with you every step of the way, from the nurses and therapists
helping you through treatment to the campaigners improving
cancer care. We are Macmillan Cancer Support.
To order a copy of Understanding brain tumours or one
of the other booklets or fact sheets mentioned in this
information, visit be.macmillan.org.uk or call 0808 808
00 00.
We make every effort to ensure that the information we provide is accurate but it
should not be relied upon to reflect the current state of medical research, which is
constantly changing. If you are concerned about your health, you should consult
your doctor. Macmillan cannot accept liability for any loss or damage resulting from
any inaccuracy in this information or third party information such as information on
websites to which we link. © Macmillan Cancer Support 2012. Registered charity
in England and Wales (261017), Scotland (SC039907) and the Isle of Man (604).
Registered office 89 Albert Embankment, London, SE1 7UQ
REVISED IN JUNE 2012
Planned review in 2014
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