Page 26 - Future Stars Science Explorer-5

Limb Bones and Girdles

The human body has two pairs of limbs. Our Pectoral girdle

arms are known as the forelimbs and the legs Upper arm bone
(Humerus)
are known as the hindlimbs. Forearm bones

Arms : In the upper arm there is only one bone Radius

and in the forearm has two bones. At the end of Ulna
the forearm are small bones of the hand which Hand bones

make up the wrist, palm and fingers. Arm bones

Pelvic girdle The upper arm bone is joined to the spine with
the help of shoulder bones or pectoral girdle.
The shoulder girdle consists of a pair of

Thigh bone (Femur) shoulder blades and collar bones.

Legs : The upper leg or thigh has a single long
bone called the femur. It is the longest bone
Knee cap
in the body. At the knee, it is joined with two

Calf bone bones of the lower leg. The ankle and toes
have many small bones.
Skin bone
The thigh bone or femur is attached to the hip

Foot bones bones or the pelvic girdle.

Leg bones
Joints

Imagine that you cannot bend your legs at the knees. Try walking from one

end of the classroom to the other. Try to climb stairs, again without bending
your knees. Now, without bending your arm at the elbow, try to lift a book

from the floor. Do you find it easy or difficult?

Our ability to bend our arms and legs makes it easy for us to do different
things. The bones bend at the joints. Joints are the places where two bones

are joined together. Our body has many joints. All joints except those in the
skull can move. The joints in the skull are called immovable joints. All other

joints are called movable joints. The lower jaw is the only movable joint in
the skull.

26 Science-5