Test: Body Movements

• A group of cells performing a particular function (special job, if you want to call it) is called a tissue. Thus, groups of specialized cells cooperate to form a tissue.
• Different tissues are in turn grouped together to form larger functional units, called organs.
• Each type of cell, tissue, and organ has a distinct structure and set of functions that serve the organism as a whole.

Skull contain least number of movable joints.The bones in the skull, except the lower jaw bone, do not allow any movement and hence, has the least number of movable joints.

There are 206 bones in the human skeleton system in all adult human beings including:
Skull – including the jaw bone
Spine – cervical, thoracic and lumbar vertebrae, sacrum and tailbone (coccyx)
Chest – ribs and breastbone (sternum)
Arms – shoulder blade (scapula), collar bone (clavicle), humerus, radius and ulna
Hands – wrist bones (carpals), metacarpals and phalanges
Pelvis – hip bones
Legs – thigh bone (femur), kneecap (patella), shin bone (tibia) and fibula
Feet – tarsals, metatarsals and phalanges.

• The ball and socket joint, the bones can be turned in any direction i.e. forward and backward, side to side and even rotated.
• The ball and socket joints occur at the shoulder and hips in our body.
  

Backbone of human being consists of 33 vertebra placed one over the other. These include:

i) 24 presacral vertebrae (7 cervical, 12 thoracic, and 5 lumbar) followed by the
ii) sacrum (5 fused sacral vertebrae) and the
iii) coccyx (4 frequently fused coccygeal vertebrae).

i) Earthworms do not have an internal skeleton as we do, and

ii) They do not have a protective hard exoskeleton as does an insect.

iii) They are flexible, long bundles of muscle, especially designed for life underground.

iv) The characteristic wriggling of earthworms is done with two kinds of muscles.

• A muscular foot comes out from the opening in the shell for movement.
• Foot of the snail is attached with it's belly.
• The foot produces wavy motions which are very slow.
  

• A single muscle can only pull, it cannot push. Thus, muscles work in pairs to move a bone.
• When one muscle contracts, it pulls the movable bone.
• When another muscle of the pair pulls, it brings the bone back to its original position.
• Muscles are attached to bones by means of tendons.

The parts of the body that help in movement are:

(i)  Bones

(ii) Joints

(iii) Contraction and relaxation of muscles.

• The ribs partially enclose and protect the chest cavity, where many vital organs (including the heart and the lungs) are located.
• The rib cage is collectively made up of long, curved individual bones with joint-connections to the spinal vertebrae.