The Soft Tissue Flashcards
What are muscles composed of?
A muscle is composed of many thousands of filaments (actin and myosin) which are contained in small bundles called myofibrils and a bundle of these forms myofibrils forms one muscle fibre
what are actin and myosin?
Actin- spherical protein that forms filaments, which are involved in muscle contraction and other important cellular processes
Myosin- is a motor protein most notably involved in muscle contraction
What are muscle fibres bound together to form?
A number of muscle fibres are bound together by connective tissue (endomysium) to form a fascicle. All of the fascicle are contained within more connective tissue (perimysium) to make up the whole muscle.
What is endomysium?
It means within the muscle, it is a wispy layer of areolar connective tissue that unsheathes each myocyte (muscle fibre or muscle cell)
What is the outer layer of muscle connective tissue?
the outer layer of muscle connective tissue (epimysium) known as muscle fascia. This has a smooth exterior surface, which allow the muscle to glide freely alongside adjacent structures.
What do the blood vessels and nerves that supply the muscle fibres run along?
They run along and through the layer of connective tissue.
What protein filaments is a muscle fibre cell made up off?
The muscle fibre cell is a basic unit of muscle contraction, it is made up of two types of protein filaments actin and myosin
Sliding filament mechanism
The thicker myosin filaments form cross bridges with the thinner actin filaments. These cross bridges move like oars of a boat and draw the action filaments in towards each other and shorten the overall length go the muscle fibre, creating a contraction
In what way does a muscle fibre contract
In an all or nothing way- it is either fully contracting or fully relaxed. If the muscle as a whole is applying 50% strength then half the muscle fibres contract and the others relax. As the contracting muscle fibres fatigue they will relax and the relaxing muscle fibres will be recruited to take up the effort.
What is a tendon
A tendon is a strong cord like structure made up of parallel bundles of collagen fibres which extends from the connective tissue surrounding the muscle and its compartments
How do tendons attach to the muscle fibres
It attaches at one end to the bone, via the peritoneum at the other end
What happens to the tendon as the muscle contracts
As the muscle contracts and shortens it pulls the tendon which, being inelastic, pulls on the bone and so creates a functional movement
What percent of stretch can the tendon allow despite being inelastic?
It can allow a stretch of 5% to enable it to absorb shock of a sudden forced stretch or contraction
What is the synovial membrane
A thin membrane of connective tissue that forms a capsule around the joint called the articular capsule, which is often made up partly by the joint ligaments
Layers of synovial membrane
It has a fibrous outer later and an inner layer which secretes synovial fluid into the joint
What is synovial fluid
A thick colourless fluid which lubricates and nourishes the inner joint structures. It is also found in the bursa and tendon sheaths
What is a ligament
A tough band of fibrous tissue that links bones together across a joint. The fibres run in parallel and in line with the direction of stress.
Are ligaments flexible
Ligaments are inelastic but flexible, so it can allow the joint to move freely within a certain safe range, but will become taut and so prevent any movement beyond it which might otherwise cause damage to the bone
What do ligaments control
they control the range of movement and protect the joint
What is the articular cartilage
A dense later of connective tissue which covers the articulating surfaces of a bone within the capsule.
what does the articular cartilage provide
A smooth surface that allows the bones to glide across each other without friction
What is fibro cartilage
some joints contain pads or discs of fibro cartilage which fill the spaces between the articulating surfaces and provide them with good fitting. They also help to prevent shock
What is the bursa
It is a sack like structure filled with fluid (synovial) which is found between the bones and soft tissues in and around the joint.
what does the bursa do
it prevents friction and allows the different structures to glide smoothly around each other as the joint moves. With a soft fluid centre it also acts as a cushion to absorb shock.
What can be found between tissues around the joints that fulfil the same role as the bursa
Small fat pads
