3: Muscles and movement Flashcards
What are the three types of muscle?
Cardiac muscle
Skeletal muscle
Smooth muscle
Which type(s) of muscle are striated?
What does this mean?
Cardiac muscle
Skeletal muscle
repeated units of muscle (sarcomeres) giving rise to a streaky appearance.
Which type(s) of muscle are non-striated?
Smooth muscle
Name the units of skeletal muscle from a microscopic to gross level.
Actin & myosin filaments
⇒ Myofibrils
⇒ Myocytes
⇒ Fascicles
⇒ Skeletal muscle
Muscle strains result from ___ muscle fibres.
torn
Skeletal muscles can only move a joint if they ___ it.
cross
Muscles (lengthen / shorten) during contraction.
shorten
What structures attach muscle to bone?
Tendons
What are tendons?
Can they contract?
Structures which connect muscle to bone
They are non-contractile
What is an aponeurosis?
A flattened tendon
Aponeuroses (flattened tendons) are usually associated with ___ muscles. They attach muscle to (bone / soft tissue).
flat
soft tissue
Skeletal muscles have at least two points of attachment to bone. What are they called?
Origins
Insertions
In terms of the origin and insertion, what is the only thing a skeletal muscle can do?
Shorten the distance between the origin and insertion along the long axis
During contraction, the origin and insertion move (closer together / further apart).
closer together
The biceps brachii has:
_ origin(s)
_ insertion(s)
2 origins
1 insertion
The direction of movement produced by a muscle depends on which __ of the joint the muscle spans.
side
What is a reflex?
What function do reflexes serve?
A rapid, predictable, involuntary movement made in response to “danger”
Protective function
When we touch something potentially damaging, there is sudden __ to withdraw from the danger.
flexion
What reflex involves sudden flexion to distance the limb from danger?
Flexion withdrawal reflex
Nerve connections involved in reflex responses are found in the (brain / spinal cord).
spinal cord
The brain is not involved in reflex responses.
What are the two main reflexes involving skeletal muscles?
Stretch reflex
Flexion withdrawal reflex
The normal reflex response to being stretched is to ___.
contract
Which reflex involves contraction after the unexpected stretch of a muscle?
Stretch reflex
What are some other names for the stretch reflex?
Biceps jerk
Triceps jerk
Knee jerk
Ankle jerk
The stretch reflex is protective against ___.
overstretching
Briefly describe the reflex arc response to muscle stretch.
1. Overstretching detected by sensory nerve
2. Sensory nerve sends impulse to synapse in spinal cord
3. Spinal cord passes message to motor nerve which induces contraction in the muscle
What name can be given to the route taken by action potentials following unexpected muscle stretch?
Reflex arc
A normal stretch reflex indicates that what is working?
The muscle
Sensory nerve fibres
Motor nerve fibres
Spinal cord connections
Neuromuscular junction
“Descending controls” from the brain
What is paralysis?
A muscle without a functioning motor supply
A paralysed muscle (can / cannot) contract.
cannot
On contraction, a paralysed muscle would have (increased / reduced) tone.
reduced
What is spasticity?
When a muscle has a functioning motor nerve but descending controls from the brain don’t work - random contraction
On examination, a spastic muscle would have (increased / reduced) tone.
increased
What is atrophy?
What causes atrophy?
Muscle wasting - myocytes become smaller to reduce muscle bulk
Inactivity
What happens to individual myocytes during hypertrophy?
Each individual myocyte enlarges
Skeletal muscle is found (superficial / deep) to the deep fascia.
deep
Within the deep fascia, muscles are held within ___.
compartments
What can caused increased pressure within muscle compartments?
Swelling of tissues
Increase in fluid (e.g bleeding)
Increased pressure in muscle compartments (positively / negatively) affects the function of muscles and nerves in the compartments
negatively
What procedure would be carried out to treat Compartment Syndrome?
Fasciotomy
