DK - WOW! The Visual Encyclopedia of Everything

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Shoulder joint

is the most

flexible joint in the body

Hip joint is

where the

ball-shaped head of the femur fits into the cup-shaped

socket in the hip bone

Sacrum anchors

the backbone

to the pelvic

girdle

Constructed from 206 bones, the human skeleton is a strong, flexible framework that supports and shapes the body and produces movement when pulled by muscles. The skeleton also protects soft, internal organs, such as the brain and lungs. Bones, which make up

20 per cent of the body’s mass, are connected

to each other at joints and are held together by strong straps of tissue called ligaments.

Skeleton

1

SKULL

The bones in the skull protect the brain, provide a framework for the face, and anchor the muscles that

produce facial expressions. The skull consists of 22 bones, 21 of which are locked together by immovable

joints called sutures. Only the lower jaw (mandible) can move.

2

CHEST

The bones of the chest

(thorax) consist of the sternum (breastbone), the ribs, and part of the backbone. Together, they form a protective “cage” that protects the lungs and the heart.

4

ELBOW

The bones of the upper arm and forearm meet at the elbow. This joint acts like a door hinge allowing the arm to bend or straighten. The forearm bones can rotate at the elbow, enabling the

palm of the hand to face upwards or downwards.

3

FOREARM

The forearm is made up of two parallel bones – the ulna and the radius. The ulna curves round the humerus to form the elbow’s point, while the radius forms a joint with the carpals (wrist bones).

Mandible moves to open the mouth for eating,

breathing, and speaking

Radius is the outer bone of the forearm

Humerus

1

2

4

3

Ulna is the inner

bone of the forearm

064_065_Skeleton.indd 64 17/01/19 11:49 AM