Intro to muscles and movement
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What does skeletal muscle consist of?
Muscle fibres & a fibrous or tendinous portion
What does skeletal muscle look like under the microscope?
The cells are multinucleate with the sarcoplasm filled with myofibrils and mitochondria
What is each muscle cell lined with?
Connective tissue
What travels through the connective tissue around the muscle?
Blood vessels and nerves to supply and innervate the fibres
What are Sharpey’s fibres?
Matrix of connective tissue consisting of bundles of type 1 collagen connecting periosteum to bone
What length in terms of a factor can a skeletal muscle contract to?
Half of its length
Why do longer muscle fibres allow for more movement?
There is a larger contraction
What is a perimysium?
Sheath of connective tissue that groups muscles fibres into bundles
What do tendons do?
Attach muscle to bone
Why are the muscle fibres as long as possible?
To maximise the distance that the body through
What does muscle size change by? 4 things
1 = increase/decrease in the diameter of the individual muscle fibres by adding new sarcomeres to existing cells 2 = Increase in length of muscle during childhood and adolescence by the addition of new sarcomeres at the ends of muscle fibres 3 = The ability to add and lose sarcomeres does not end when normal growth ends due to the role of exercise adding / removing sarcomeres 4 = Muscle bulk and strength decrease with age but exercise can slow down or reverse the trend
What are the 3 types of tendons?
• Cylindrical where fibres are closely packed to form a cylinder • Linear tendons forming a fleshy attachment and may produce a linear bridge • Common tendons which are attached to 2 muscles or more in 3 forms (intermediate, raphe or aponeurosis)
Where are synovial tendon sheaths found?
Around the wrist and ankle
What are the two types of innervation?
Sensory - muslce spindles measure the length and tendon organises tension while other nerves are involved in proprioception and pain. Motor - Myelinated fibres from large motor neurone end in motor end plates. The transmitter ACH crosses the gap and activates the muscle fibre.
What is an advantage of a parallel muscle?
It gives a large range of movement
What is a pennate muscle built for? What structure allows this?
Built for power and there is a central tendon with fleshy bellies attached
What is an antagonist muscle?
Muscles are attached to the opposite side of bones and oppose the movement.
What is the role of a fixator in muscle action?
They stabilise the body for the required movement. Thus when the prime movers and the antagonist act together they can hold the bone in a fixed position.
What is the role of a synergist in muscle action?
These act with the prime movers to refine the movement and to control any undesirable movement. Thus when a joint is capable of moving in more than one plane the synergist control the unwanted movement.