Great anatomy programme on BBC4 last night. My tweet about lever action was picked up by @DrAliceRoberts. The anatomist said that long tendons increase leverage,which is just nonesense.
Most of the levers in the body are designed to increase travel from muscles that cannot generate a lot of movement. They are therefore inefficient as levers. Tendons allow the muscles, which are bulky and generate relatively short travel, to be mounted inboard. That reduces the mass of the extremities, increasing potential rate of movement. They also allow the many fibres in a muscle to be gathered into a narrow "rope" to travel through difficult and conjested areas.
The lever action is controlled by the shortest distance between the centre of rotation of the joint and line of actio of the tendon. These distances are greatest at the shoulder elbow, knee and ankle and, less obviously at the hips. At those joints, the tendons are very obvious, cutting across the corner at shoulder, elbow and knee. The ankle is the odd one out where the big lever is positioned to extend rather than retract the joint.
The ankle is thus a second order lever, where the load at the fulcrum is greatest. The others are third order the force at the fulcrum and the load both act on the muscle which is therefore very inefficient in terms of force conversion.
A side effect of these, apparently inefficient levers is that control is much more difficult since small movement in the mucle often results in very large movement at the end of the limb.
So, my take on those aspects of anatomy:
Muscles are bulky and relatively weak. They need to be atyached to bone, preferably in a very narrow area so the weak muscle fibres are attached to very thin films of tendon that gather into a rope to attach to the bone.
Just like a rope, the tendons can be led round corners but there are no pulleys. The fairleads are simple low friction tubes with all the danger of damage they have.
The levers are purposely inefficient in terms of force so that they can generate large fast movements when necessary.
Controlling a system where small movements generate large ones is very dfficult. We have learnt to overcome that by resting the hand (for example) so that only the finest movements have to be controlled.
And much of that was there in Alice's own program with George McGavin.
And since typad offers me some links I will add them though I have some doubts about the way they are presented.