How the Brain Works The Facts Visually Explained by DK (z-lib.org)

Brain

Spinal cord

Peripheral

nerves extend

through torso

and limbs to

hands and feet

Spinal nerves of

peripheral system

join spinal cord

of central system

Sciatic nerve

is largest and

longest nerve

in body

The nervous system

The two main parts of the nervous system are the central

nervous system (CNS) and the peripheral nervous system.

The CNS is made up of the brain and the spinal cord, a

thick bundle of nerve fibers that runs from the brain in the

head to the pelvis. Branching out from this is the peripheral

system, a network of nerves that permeates the rest of the

body. It is divided according to function: the somatic

nervous system handles

voluntary movements

of the body, while the

autonomic nervous

system (see opposite)

handles involuntary

functions.

KEY

The Brain in the Body

The brain is the primary component of

the human body’s nervous system, which

coordinates the actions of the body with

the sensory information it receives.

Spinal nerves

Most peripheral nerves

connect to the CNS at the

spinal cord and split as they

connect. The rear branch carries

sensory data to the brain; the

forward branch carries motor

signals back to the body.

Permeating the body

The nervous system extends

throughout the entire body.

It is so complex that all of a

body’s nerves joined end to

end could circle the world

two and a half times.

Central nervous

system (CNS)

Peripheral

nervous system

Within the peripheral system,

12 cranial nerves connect

directly to the brain rather

than the spinal cord. Most link

to the eyes, ears, nose, and

tongue and are also involved

in facial movements, chewing,

and swallowing, but the vagus

nerve links directly to the heart,

lungs, and digestive organs.

CRANIAL NERVES

Skull provides

protection

to brain

Signals along

optic nerve

travel directly

to brain

Spinal

cord

VERTEBRA

SPINAL NERVE

CORDSPINAL

Sensory and

motor nerves are

often bundled

together,

separating at

their ends

Bone

vertebra

protects

spinal cord

Spinal cord

runs down

back, through

vertebrae of

spinal column

Sensory

nerve

Motor

nerve

SPINAL COLUMN (REAR VIEW)

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