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Revision Notes on Body Movements

Our body is capable of performing a wide variety of simple and complex functions. It is able to do so because of the internal structure that facilitates its movement.

Human Body And Its Movements

The human skeleton is the internal framework which is responsible for giving support, shape and protection to our bodies. It contains 206 bones, each playing a distinct yet important task. The skeleton can be classified into two parts called as the axial and the appendicular. The axial skeleton comprises of the central part of the skull, spine, and ribs and the appendicular skeleton consists of the arms and legs.

Terms -

Limbs: The arms or legs of an animal.

Bones: These are the hard white structures below our skin that protect our internal organs. Bones are incapable of bending.

Joints: These are defined as the points at which two bones are fitted together. These are the points at which we can rotate and bend our bodies.



Figure 1: Body Movements

Types of Joints and their Location in Human Body


	

	
A Pivot joint is a joint that rotates.. Examples of pivot joints in the body in the neck that allows the head to rotate and the ones between the radius and ulna that allow forearm rotation.
	
	

	
When bones can move along one axis, it indicates the presence of Hinge joint. e.g. Elbows and Knees.
	
	

	
In the Ball and Socket joint, a partial spherical structure is present inside a socket allowing movement in all directions. e.g. hips and arms
	
	

	
As the name suggests Fixed joint allows no movement to occur. e.g Skull
	




Figure 2: Types of Joints

Important Points to remember in a Human Skeleton: 


	

	
Bones provide support, protection, movement and perform several other functions.
	
	

	
The bones in the skull (Cranium, Mandible, Maxilla) give protection to the brain.
	
	

	
The long bones such as humerus, radius, ulna, tibia, fibula support the weight of body
	
	

	
The carpals are located in wrist and tarsals are located in ankles. They are examples of short bones.
	
	

	
The bones protecting the spine are called as the vertebral column. Cervical area (top 7 vertebrae), Thoracic (next 12), Lumbar (bottom 5 vertebrae), Sacrum (5 fused or stuck together bones) and Coccyx (the tiny bit at the bottom of the spine).
	
	

	
The sternum and rib cage constitute the chest bones.
	




Figure 3: Human Skeleton

Some More Points to Remember



Gait of Animals

1. Earthworm: 


	

	
Does not have bones
	
	

	
Earthworm body is made up of rings
	
	

	
A slimy substances secreted by its body aids movement (NSO)
	




Figure 4: Detailed Movement in Earthworm

2. Snail:


	

	
It has a slimy body, which does not have bones.
	
	

	
The shell of the snail does not help in movement. It has to be carried along.
	
	

	
The foot of the snail is a thick structure and is made up of strong muscles.
	
	

	
A muscular organ called ‘Foot’ helps in locomotion.
	




Figure 5: A Snail


	
		
	
	

		

			
Cockroach
			

			

				

				
Belongs to Phylum Arthropoda
				
				

				
Its Exoskeleton is hard and stiff.
				
				

				
3 pairs of legs help in walking and 4 wings help to fly
				
				

				
The body muscles move the wings when it flies
				
			
			
		
		

			
Fish
			

			

				

				
Presence of scales on the fish skin reduce  frictional drag
				
				

				
It possess a streamlined shape which enhances locomotion
				
				

				
Coordination between muscles and tail help the fish to move.
				
				

				
Fins aid the movement in the water
				
			
			
		
		

			
Birds
			

			

				

				
Their forelimbs are modified into wings 
				
				

				
Presence of hollow and light bones, which reduces weight.
				
				

				
Hind limbs help in walking and perching
				
				

				
They have strong shoulder bones
				
			
			
		
		

			
Snakes
			

			

				

				
Presence of long backbone and thin muscles.
				
				

				
Loops made by its body help in moving forward.
				
				

				
Moves fast but not in a straight line
				
				

				
They cannot move on frictionless surface.
				
			
			
		
	

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