Skeletal Muscle and Movement Flashcards
What are the properties of skeletal muscle
It is striated and under voluntary control.
What are the properties of visceral (smooth) muscle
It is non-striated and under involuntary control.
What are the properties of cardiac muscle
It is striated and under involuntary control.
How long does it usually take substantial muscle damage to repair
A long time.
What is the best producer of heat in the body
Skeletal muscle
Around how much of the body weight is skeletal muscle
40%
What are the 6 functions of skeletal muscle
- Movements
- Maintenance of posture
- Heat production
- Storage
- Protection
- Blood flow
What are 4 specialisations/characteristics of skeletal muscle
Irritability (excitability), contractility, extensibility and elasticity.
What is meant in describing skeletal muscle as irritable
It reacts to electrical stimuli.
What is a myofibril
The smallest until in the elongated part of a muscle cell.
What is unique about the nuclei on muscle fibres
The nuclei are peripherally located.
What does it indicate if the nuclei of muscle fibres migrate to the centre from the periphery
This indicates pathology.
What are the two types of myofilaments
Thick myofilaments and thin myofilaments.
What is the most important region of muscle fibres
The sarcomere.
What is the area between two z lines in a muscle fibre important for
Contraction and growth.
Which myofilaments are the mobile part of the contractile element
The thin myofilaments
What happens to the myofilaments in the contractile element on extension
The thin myofilaments move away from the centre while the thick myofilaments remain the same.
What happens to the myofilaments in the contractile element on contraction
The thin myofilaments move towards the centre while the thick myofilaments remain the same.
What action causes the thin myofilaments to move away from the centre of the contractile element
Extension
What action causes the thin myofilaments to move towards the centre of the contractile element
Contraction.
What is the name given to the three connective tissue coverings
Fascia
What are the three fascia
- Epimysium
- Perimysium
- Endomysium
What is the outermost fascia
The epimysium. This covers the entire muscle.
What are fasiculi
This is the name given to the unit of grouped together muscle fibres
What is the name given to the fascia that surrounds all of the individual fasiculi
The perimysium
What is the name given to the fascia that covers each individual muscle fibre
The endomysium
From superficial to deep, what is the arrangement of the fascia in muscle
Epimysium-perimysium-endomysium
What happens to the connective tissue coverings in intramuscular injection
In intramuscular injection, muscle fibres become damaged and the surrounding connective tissue proliferates.
What is the aponeurosis
The flat connective sheet covering the abdomen.
What are two skeletal muscle attachments
Tendon and aponeurosis.
What is the general rule for the origin and insertion of a muscle
GENERALLY -
- the origin is the attachment of the muscle’s tendon to a stationary bone
- the insertion is the attachment of the muscle tendon to a moveable bone.
What is the exception to the general rule of origin and insertion of a muscle (that origin = attachment of muscle tendon to stationary bone and insertion = attachment of muscle tendon to movable bone)
The pectoralis major muscle. The origin of this is the sternum and the clavicle while the insertion is the humorous. The origin can become the insertion, for example when asthmatics are trying to get in more air.
How many joints will a muscle act on
A muscle will act on as many joints as its tendon crosses.
What are muscle fibres arranged into
Bundles called fasiculi.
How are muscle fibres arranged within fasiculi
Muscle fibres are in a parallel arrangement however the number of muscle fibres within individual fasiculi varies and the types of muscle fibres present also varies.
What does the arrangement of fasiculi determine in terms of the muscle as a whole
The shape of the muscle, the degree to which the muscle can contract and the force the muscle can generate.
What is fasicualr arrangement a compromise between
Power and range of movement.
What does the maximum force a muscle can generate depend on
The mass of contractile tissue.
What does the maximum range of unrestricted movement in a muscle depend on
The length of muscle fibres.
What does low power tend to mean in terms of range of movement in a muscle
Range of movement is increased.
What does high power tend to mean in terms of range of movement of a muscle
Range of movement is decreased.
What is an example of a high power, limited range of movement muscle and what shape does this muscle take
The deltoid muscle which is a pennate muscle.
What is an example of a limited power but increased range of movement muscle and what shape does this muscle take
The Sartorius muscle which is a straplike muscle.
What do bones function as when producing movement
Levers - a rigid rod.
What do joins function as when producing movement
A fulcrum - a fixed point
What are the muscle compartments of the upper limb
The anterior (flexor) and posterior (extensor) compartments.
What are the muscle compartments of the lower limb
The anterior (flexor), posterior (extensor) and medial compartments.
What is a motor unit
A motor neuron and all the muscle fibres it innervates..
What are two types of muscle fibres
Slow muscle fibres and fast muscle fibres.
What can change the muscle fibre composition of fascicles
Long term alcoholism
What is the effect of interruption to the nerve supply of a muscle on the muscle fibre composition
This results in lumps of slow fibres and lumps of fast fibres.
What are three requirements for muscle fibres
Innervation, blood supply and venous drainage
