myology

Question 1

types of skeletal muscle: parallel

Answer 1

• parallel: muscle fibres run from one attachment of muscle to other = in line of pull of muscle
  4 types:
• strap-like: the muscle is as thick in the middle as it is at the end e.g. sartorious
• fusiform: thick in the middle but tapers out at the ends e.g. biceps
• triangular/convergent: apex = one insertion, base = another insertion e.g. trapezius
• flat (quad): has four sides e.g. pronator quadratus
  = DESIGNED FOR ROM

Question 2

types of skeletal muscle: oblique (pennate)

Answer 2

oblique: structure of a feather = muscle fibres run oblique to line of pull of muscle 
3 types:
- unipennate
- bipennate
- multipennate 
= ARE DESIGNED FOR FORCE/POWER

Question 3

Structure of a Sarcomere - myofilaments in the sarcomere

Answer 3

dArk bands:
- A band: contains whole length of myosin (thick) filaments + any actin overlap
- H band: the length of mysoin w/o actin overlap = myosin only
- M line: a protein ring within H band that supports myosin
lIght bands:
- I band: contains actin (thin) filaments (and titin) without myosin overlap = ACTIN ONLY
- Z line: line that joins adjacnet sarcomeres (contain actin and titin filaments)

Question 4

Sarcomere during contraction

Answer 4

• myosin (thick) filaments stay still while actin (thin) filaments move into the A band
• Z lines move closer together
• I BAND SHORTENS, A BAND STAYS THE SAME

Question 5

Slow + fast fibres

Answer 5

Slow:
- smaller diameter
- darker colour (due to myoglobin)
- fatigue resistant
Fast:
- larger diameter
- paler colour
- easily fatigued

Question 6

The Myotendinous Junction (MTJ)

Answer 6

• Force generated by muscle fibres is transmitted through the MTJ
• Is a potential site of weakness
• The MTJ receives blood supply from the muscle: it is hypovascular (not a great blood supply) = prone to injury + difficult to repair as hypovascular = doesn’t get enough oxygen + nutrients