Inserting tendons
-fibrocytes/blasts are capable of producing both bone and fibres and so at the boundary the fibres of tendons become part of the bone which is built around the fibres, hence there is a very intimate gradation from purely fibrous to purely bone such that in injury, tendons can pull bone off the shaft.
Actions of Skeletal Muscles
- the force and perpendicular distance are important concepts as oment=focexdistance. Hence constraints on the actions of muscles include muscle length and pennation. Extra force can then be achieved by increasing corss section area of the muscle, placing the insertion more remote to the joint or changing the angle of insertion. The joint rotation angle can be increased by increasing the contraction distance of the muscle or placing the insertion point closer to the fulcrum. THe speed of joint rotation can be increased byplacing the insertion closer to the fulcrum, increasing muscle strength or reducing the mass of the distal limb.
Problems with tendons
- tendons shorten the distance between origin and insertion and as the joint rotates they lift from flexor surfaces and wrap onto extensor surfaces. Hence tendons need to be tied to flexor surfaces (retinaculum) and sesamoids are needed on extensor surfaces.
Knowledge Test
1. what is a retinaculum and what is its function?
Concept test.
1. describe how muscular force is transferred to bone.
2. as a limb designer, you have the option of inserting a muscle at a distance two times distant to the joint than it currently inserts. What are the consequences for the size and shape of the muscle if: you aim to preserve the force applied by the muscle? you aim to preserve the timing of parts of the movement (stride) cycle?
-fibrocytes/blasts are capable of producing both bone and fibres and so at the boundary the fibres of tendons become part of the bone which is built around the fibres, hence there is a very intimate gradation from purely fibrous to purely bone such that in injury, tendons can pull bone off the shaft.
Actions of Skeletal Muscles
- the force and perpendicular distance are important concepts as oment=focexdistance. Hence constraints on the actions of muscles include muscle length and pennation. Extra force can then be achieved by increasing corss section area of the muscle, placing the insertion more remote to the joint or changing the angle of insertion. The joint rotation angle can be increased by increasing the contraction distance of the muscle or placing the insertion point closer to the fulcrum. THe speed of joint rotation can be increased byplacing the insertion closer to the fulcrum, increasing muscle strength or reducing the mass of the distal limb.
Problems with tendons
- tendons shorten the distance between origin and insertion and as the joint rotates they lift from flexor surfaces and wrap onto extensor surfaces. Hence tendons need to be tied to flexor surfaces (retinaculum) and sesamoids are needed on extensor surfaces.
Knowledge Test
1. what is a retinaculum and what is its function?
Concept test.
1. describe how muscular force is transferred to bone.
2. as a limb designer, you have the option of inserting a muscle at a distance two times distant to the joint than it currently inserts. What are the consequences for the size and shape of the muscle if: you aim to preserve the force applied by the muscle? you aim to preserve the timing of parts of the movement (stride) cycle?