Skeletal Muscle Flashcards
Give the order (largest to smallest) of the components of skeletal muscle
Epimysium ➡️ perimysium ➡️ fascicles ➡ endomysium ➡️ fibres
What is skeletal muscle needed for?
Movement
Posture
Stability of joints
Heat generation
What kind of muscle is it if it has parallel fibres, often with an aponeurosis?
Flat
A muscle has a feather-like arrangement - name?
Pennate
A muscle is spindle shaped with a round, thick belly and tapered ends
Give an example
Fusiform
Biceps
A muscle arises from a board area and converges to a single tendon
Convergent
Pec major
A muscle has four equal sides
Quadrate
A muscle that surrounds a body opening/orifice, constricts when it contracts
Circular/sphincteral
More than one head of attachment or more than one contractile belly
Multihead or multibellied
Name the four muscle groups
Agonists/prime movers
Fixatives
Synergists
Antagonists
What is compartment syndrome?
If an artery bleeds, can compress the nerve within the compartment and cause pain and parasthesia.
Give characteristics of slow twitch
Darker and red appearance Many mitochondria Aerobic respiration High myoglobin Rich capillary supply Fatigue resistance and endurance
Give characteristics of fast twitch type IIa (fast oxidative)
Aerobic High myoglobin Red-pink colour Many mitochondria Rich capillary supply Moderate fatigue resistance
What is type IIa good for?
Walking/sprinting
What is type IIb good for?
Short, intense movements
What are characteristics of IIb?
Anaerobic glycolysis Low myoglobin Pale appearance Few mitochondria Poorer capillary supply Rapidly fatigable
What does tonic contraction allow?
Stability of joints and maintenance of posture
What type of muscle contraction lengthens the muscle to exert a force. Can cause delayed onset of muscle soreness?
Eccentric
What is hypotonia?
Low muscle tone
What can cause hypotonia?
Damage to motor cortex Damage to cerebellum Shock/damage to spinal cord Lesion of sensory afferents from muscle spindles Primary degeneration of muscles Legion of lower motor neurones
What can be used to diagnose MND by picking up electrical activity in muscle?
Electromyography
Name some sources of energy for contraction and when they would be used
Short term stores of ATP (first few seconds)
Creatine phosphate + ADP ➡️ ATP + creatine (up to 15 secs)
Anaerobic glycolysis and lactate (20-40 secs)
Aerobic respiration/oxidative phosphorylation (long time)
What is peripheral fatigue in muscles?
Depletion of muscle glycogen
Occurs within 1 minute if blood flow is interrupted
What is contracture?
State if continuous contraction which occurs when ATP runs out as the myosin head cannot be removed from actin - rigor mortis
Name the two types if phasic (active) contraction
Isotonic and isometric
What is isotonic contraction?
The muscle changes length in relation to the production of movement
What is isomeric contraction?
Muscle length remains the same, but the force is is increased above tonic levels to resist gravity or other antagonistic force. Important in maintaining upright posture
What actions might use concentric contraction?
Lift a cup
Push a door
Punching
When is eccentric contraction used?
Walking
Running
Setting objects down
Sitting down
What is the main muscle of a particular movement called?
The prime mover
What is a motor unit?
A motor neuron and the muscle fibres it controls - makes up a functional unit
