Understanding how our bodies work can help us greatly in class, and vice versa - we can learn some biology from our dancing! Ever wondered what we actually mean when we ask you to point through the metatarsals, or contract a muscle? Or perhaps you've just never quite been sure where the Achilles tendon actually is... let alone what it's there for. These pages are designed to help you understand these things.

How bodies move
Bones
Joints
Muscles
What happens when we point our feet?
Taking care of the body

How bodies move

The human body is a complicated machine that we usually take for granted. Have you ever thought about how you are able to dance?

Movement is the result of our muscular and skeletal systems working together. Our bones gives us a solid frame to which the muscles can be attached - without it we would be like blobs of jelly. The skeleton also protects our organs. Joints between bones allow us to move and bend. Ligaments join bone to bone and tendons join muscle to bone. The muscles connect the bones, pulling them (by contracting and relaxing) into place. The muscles are controlled by our nervous system, i.e. by messages sent from the brain. The muscles can be strengthened by exercise.

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Bones

An adult human skeleton is made up of about 206 bones! How many do you know?

Sometimes it is helpful to think of the skeleton in two parts

• the central ("axial") skeleton made up from the skull, backbone and breastbone, whose job it is to protect the vital organs
  
• the movement ("appendicular") skeleton, made up from the bones in the arms, legs, collar bone, shoulder blades and pelvis.

It is this second set of bones we have most control over to help us dance.

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Joints

The place where two bones meet is called a joint. There are over 100 joints in the body which allow us to move. Here the bones are held together by ligaments, tissues which stop the bones from moving apart (dislocating). Joints are often split into three categories: immovable (eg between the skull bones, pelvis), slightly moveable (eg joints between the vertebrae in the spine) and freely movable joints.

Most joints in the body are movable, very flexible and contain a fluid (synovial fluid) to keep them moving freely. Here are diagrams showing the different types of joints:

hinge	(eg elbow, knee)		movement up and down from one bone fitting into the rounded part of the other	We use this joint in plies to allow our legs to bend. It is also the joint used in petit battement.
ball & socket	(eg shoulder, hip)		bones slide over one another since they are almost flat	The rotation of the ball and socket joint of the hip is what gives us our turnout.
gliding	(eg joints in the foot and wrist)		circular movement from the rounded head of one bone fitting into a socket of another
pivot	(eg top two vertebrae inside head)		movement from side to side created by one bone fitting into the ring shape of another	When we turn our heads, we are using a pivot joint. This is important for presentation but also has a particular function in pirouettes or turns, where "spotting" helps us maintain our balance.
saddle	(base of the thumb only)		rocking motion with limited rotation

This picture shows us how the skeleton is able to move and dance:

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Muscles

There are 650 muscles in the body! When we exercise, we do not grow more muscles but our muscles become stronger, larger and firmer giving us the strength we need to dance.

Muscles are attached to bones by tendons and connect over joints to allow bending at the joint.

Muscles work by contracting (becoming shorter and wider) and relaxing (becoming longer and narrower) when stimulated by a message from the brain. As the muscle changes length, it pulls on the tendon which in turn pulls the bone causing movement. Muscles have to work in pairs, because they can only pull. They cannot push, so instead they have to have a partner to pull in the opposite direction. These pairs ("antagonistic pairs") are made up of a bending muscle (the "flexor") and a straightening / extending muscle (the "extensor"). These muscles work together at every joint positioning the bones as required.

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What happens when we point our feet?

Most of us need reminding to point our feet from time to time! But have you ever really understood what happens when you point? Let's see what the foot looks like in detail:

Here is a side view of the foot and ankle. The foot is made up of 26 separate bones! See how the bone structure is connected by the ligaments?
	From above, in this picture we can again see the bones (also shown separetely on the right) but now we are looking at the muscle structure and associated tendons. You can see how the muscles are attached to the bones to allow movement. When you point your foot, your brain sends messages (via nerves) to the muscles. First the ankle joint straightens. The ankle is actually quite complex, since the tibia, fibula (lower leg bones) and talus (ankle bone) all join here. It is the Achilles tendon at the back of the ankle that is responsible for this flexing motion of the foot, since it connects the calf muscle and the heel of the foot. The Achilles is the strongest and largest tendon - it can take strains equivalent to six times our own body weight when we run and jump. However, it is also prone to injury which is why it is especially important to warm up thoroughly (see below) by gentle stretching.
As you point, the muscles on the underside of the foot contract, becoming shorter, and those on the top relax and lengthen, causing the foot to curl in the familiar way. Often you may hear us in class telling you to point right through the metatarsals: now you can see what this means. The metatarsal bones are marked - these are the lower bones of the foot, just before you reach the three individual toe bones (phalanges). If you point your foot with only a little effort, you often only send messages to the muscles connected to your ankle, the bones in your upper foot and your toes, so your foot curves a bit but not fully! If we work hard, we can use the whole foot, and point right through the metatarsal bones to create curvature through the entire foot. This is a perfect point.

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Taking care of the body

Dancing is a great way to stay healthy. Exercise makes our bodies stronger and hence more resistant to disease. Our hearts become strong and our lungs work more efficiently, supplying more oxygen to our cells. This gives us more energy for our day to day lives and helps us feel happy, even under stress. Coming to class is also a brilliant way to make new friends.

It is important to take care of the body, as it is delicate and needs looking after. It is crucial to warm up carefully before class to avoid hurting ourselves. As well as exercise, it is also important to get enough sleep and eat healthily.

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