L.8 Muscles pt.2

Question 1

L.O.

Answer 1

• Describe briefly how tendons attach to bone.
• Understand the broad mechanical principles behind muscle movements, and describe actions in correct terminology.
• Distinguish between the different types of muscle contractions, including tone, and describe (with examples) how they work together to move joints.
• Explain broadly how nerves and vessels interact with muscles and help them function.

Question 2

How Muscle interacts with bone at attachment

Answer 2

Sharpeys fibres/ Perforating fibres
- Attach tendons and ligaments to bone
- Parallel collagen fibres that extend into the periosteum and embed into the bone matrix

[heft]

Question 3

Examples of muscle actions on joints

Answer 3

Flexion:
- Decrease angle at joint

Extension:
- Increase angle at joint

Occurs on sagital plane

Abduction:
- Moving away from midline of body

Adduction:
- Moving twards midline opf body

Occurs on coronal place

Question 4

nerves activating muscles

Answer 4

Motor unit:
- Motor neuron and the muscle fibres it controls

Can be very few or hundreds, depending on specific function
Nerves usually activate the muscle they pass through from deeper site
In wide muscles, nerves can stimulate parts individually to change muscle action. eg. deltoid

Question 5

pennation

Answer 5

Compared with flat muscles, pennate muscles are stronger as there are many more fibres.
Pennation = less contraction but more fibres contracting simultaneously (stronger)

Unipennate:
- Muscle fibres insert at angles to one side of tendon

Bipennate:
- Muscle fibres insert at angle to both sides of tendon
- Feather

Multipennate:
- Collection of bipennates

Question 6

Mechanical advantages at joints

Answer 6

• Length of tendon has impacts
• joint may need to be put in certain position to maximise the contraction of the muscle fribres

Question 7

Types of muscle contraction

Answer 7

Isotonic contraction= Muscle change length for movement
- Concentric = muscle shortens to produce movement
- Eccentric = Contracting but lengthening to produce controlled movement

Isometric contraction:
- Muscle length remains the same
- No Movement
- Resists against gravity/ other force

[heft]

Question 8

Muscle functions

Answer 8

Prime mover:
- Agonist
- Concentric contraction

Synergist:
- Helps prime mover
- Does similar action or steadies a joint

Fixator:
- Steadies proximal limb segments
- Isometric contraction

Antagonist:
- Opposes action of prime mover
- Eccentric contraction

Question 9

Muscle tone

Answer 9

• Muscles are always contracted
• Does NOT cause movement, but keeps the muscles slightly stiff and maintain posture/ stability
• Abscent during anaesthesia/ nerve lesion

Question 10

How Mucles are Fed

Answer 10

• Supplies by arteries
• Often have multiple arteries in contact with muscle
• Tendons also have come blood supply, from belly to bone
• Endurance training increases number of vessels to muscle
• Strength training increases number of muscle fibres