The Skeletal System

What each part allows, and what it stops

It is easy to treat this topic as a vocabulary test: nineteen bones, six functions, two joints, a handful of movements. Learn the list, hope it comes up. There is a better way in, and it is the one the exam questions are actually built on. ⚠️ EVERY PART OF THE SKELETON IS DEFINED BY WHAT IT ALLOWS AND WHAT IT PREVENTS. A joint PERMITS certain movements and forbids the rest. That is not a limitation; it is the point of it. Your knee refuses to rotate, and you should be glad. A ligament ALLOWS a joint to move while PREVENTING it from coming apart. Cartilage PREVENTS the bone ends wearing on each other. And a flat bone like the cranium PERMITS nothing at all to reach what is behind it, which is exactly why the skull is shaped as it is and the femur is not. ⚠️ Ask "what does this part allow, and what does it stop" and most of the naming looks after itself, because the shape and the job explain one another. One warning before you start, and it will save you marks. ⚠️ This specification recognises TWO joint types. Other boards recognise four. Step 4 makes clear which two, and why revising from the wrong board's material is a real risk here.

Words for the joints and what holds them

Six terms. What each part is, with nothing yet about which movements anything permits.

Find the bone that protects the brain

One of the skeleton's six functions is protection, and some bones exist almost entirely to do it. Tap the bone whose job is to let nothing at all reach the brain.

Two joints, two sets of permissions

This specification recognises exactly two joint types. The third column is the warning that goes with that.

Why a knee will not rotate

A player can swing their arm in a full circle at the shoulder, but cannot rotate their lower leg at the knee in the same way. What actually explains the difference?

• The shape of each joint. A rounded head sitting in a cup-shaped socket can turn on any axis, while a hinge is shaped to move on one axis only
• The muscles around the knee are simply not strong enough to rotate it
• With enough training the knee could be made to rotate as freely as the shoulder
• Cartilage in the knee physically blocks rotation, and the shoulder has none

How to answer a movement question

PE questions rarely ask you to name a bone for its own sake. They describe a sporting action and ask what is happening, and a list of body parts scores very little. ⚠️ A FULL ANSWER HAS THREE PARTS, AND MOST ANSWERS GIVE ONE. ONE: name the JOINT involved. Be specific about which one, since a single action usually involves several. TWO: name its TYPE. This is the step that gets skipped, and it is what licenses the rest of the answer: the type is what makes the movement possible. THREE: name the MOVEMENT, using the proper term. Bending is flexion. Straightening is extension. Moving a limb away from the midline of the body is abduction, and back towards it is adduction. ⚠️ Say what is moving, not what the athlete is doing. "They jump" describes the sport. "Extension at the knee and the hip" describes the anatomy, and only the second one is being marked. And watch for actions that need more than one joint. ⚠️ If a question offers several marks, it is usually telling you that more than one joint is involved - so check the whole limb before you stop writing.

Match each joint to the bones that meet there

True about what the skeleton does

Select the TWO statements that are true.

• Blood cell production is one of the skeleton's functions, and it happens inside certain bones
• Bones act as a store of minerals for the body
• The skeleton produces movement by itself, without muscles
• Protection is provided mainly by the long bones of the arms and legs

The tissue that says no

Ask what holds a knee together and the honest answer is: several pieces of tough tissue whose entire job is to refuse. A ligament runs from bone to bone across a joint. It is not elastic, and it is not there to help you move. ⚠️ It is there to STOP the joint doing things that would damage it - sliding too far, twisting sideways, coming apart under load. Which is why a ligament injury is so serious for an athlete. A torn ligament does not make the joint weaker at moving. It makes the joint unable to refuse, and a joint that cannot refuse is a joint that dislocates. ⚠️ Now set the three tissues side by side and the difference is obvious, where before it was three similar words. A LIGAMENT PREVENTS. Bone to bone, holding the joint within its limits. A TENDON TRANSMITS. Muscle to bone, carrying the pull that actually produces movement. CARTILAGE PREVENTS WEAR. Covering the bone ends so they glide instead of grinding, and absorbing the shock of landing. ⚠️ Two of those three prevent something, and only one causes movement. If an exam answer says a ligament moves a bone, it has swapped the ligament for the tendon - and that is the single commonest error on this part of the specification.

The movement run

Five questions on joints, movements and the bones involved. Three lives.

Spot the true skeletal facts

Tap the TWO statements that are true.

• A ligament joins bone to bone and helps stop a joint coming apart
• A hinge joint permits flexion and extension only
• A tendon joins one bone to another across a joint
• This specification requires you to know four types of joint

Complete the movement facts

Bending a limb at a joint, so that the angle between the bones decreases, is called _____. Straightening it again is _____. Moving a limb sideways away from the midline of the body is _____, and bringing it back towards the midline is _____.

Order these bones from top to bottom

Six named bones. Put them in order of where they sit in the body, highest first.

• Cranium
• Clavicle
• Humerus
• Pelvis
• Femur
• Tibia

Build the movement description

A sprinter drives their leg backwards to push off the blocks. Assemble the three-part description an examiner is looking for.

Three sporting actions to judge

Three pieces of student writing to assess. Each answer has to carry the reasoning, not just the correction.

• A student writes that "the ligament pulls on the bone to lift the arm". What has gone wrong?
• A student revising from a friend's notes writes a long answer classifying the joints of the body into four types, including pivot and condyloid. What should they be told?
• Asked to analyse a basketball player shooting, a student writes: "They bend down, then jump up and push the ball at the hoop." Why does that score poorly?

Explain what the skeleton lets you do

A classmate has learned all nineteen bones and still loses marks on movement questions. Write them the explanation that turns the list into an answer.

• Give three of the skeleton's functions, including at least one you cannot see happening
• Explain the difference between a hinge joint and a ball-and-socket joint in terms of what each one permits
• Name a joint of each type, saying which bones meet there
• Explain the difference between a ligament and a tendon, making clear which one prevents and which one transmits
• Finish by describing one sporting action, naming the joint, its type and the movement