Muscles and Movement Flashcards
What are the 3 types of muscle?
Cardia (involuntary & striated) Smooth Muscle (involuntary & non-striated) Skeletal Muscle (voluntary & striated)
What is a sarcomere?
The repeating unit between two Z-lines
What is the sequence of skeletal muscle structure
Skeletal muscle - Fascicles - Muscle fibres - Myofibrils - Actin & Myosin microfilaments
Why does skeletal muscle look ‘striped’ when viewed histologically?
Overlapping actin & myosin
What happens at a histological level when a skeletal muscle is “strained” / “pulled”?
Some of the muscle fibres are torn
What are the different types of skeletal muscle (5)
- Circular - orbicularis iris
- Pennate - deltoid
- Fusiform - biceps brachii
- Quadrate - rectus abdominus
- Flat with aponeurosis - external oblique
Under what condition can skeletal muscle move a joint?
If they span it, i.e. have to cross the joint
Attach to bones before and after the joint
During contraction, skeletal muscles….
shorten
Muscles (usually) attach to bone via…
tendons
What is an aponeurosis?
A flattened tendon
What are flattened tendons most commonly associated with?
Flat muscles
What are the points of attachment of a muscle to a bone called
Origins and insertions
The only thing a skeletal muscle can do is…
contract, i.e. muscle fibres shorten along the long axis between the origin and insertion
The action(s) of a muscle are determined by…(4)
- the joints spanned
- long axis of the muscle fibres
- aspect(s) of the spanned joint(s)
- shapes of the articular surfaces of the join(s), i.e. limits to movement in any direction
Which joints does the biceps brachii span and which movements does it cause? (3)
Anterior shoulder joint - flexion
Anterior elbow joint - flexion
Anterior proximal radioulnar joint - supination of the forearm
Which joint (1) does the deltoid muscle span and which movements does it cause (3)?
Crosses the shoulder join
Posterior fibres - extension
Middle fibres - abduction
Anterior fibres - flexion
Usually skeletal muscles are named according to a combination of…
shape / location / size / main bony attachment / main movement
What is a reflex?
A rapid, predictable, involuntary reaction to “danger” – protective
What controls a reflex?
Nervous system and muscles do it automatically
What are the 2 main reflexes involving skeletal muscles?
Stretch reflex
Flexion withdrawal reflex
What is a flexion withdrawal reflex?
Sudden flexion to withdraw from danger
What is the role of the brain in reflexes?
It isn’t involved - the nerve connections are at spinal cord level
Name the common deep tendon stretch reflexes (4)
Biceps / Triceps / Knee / ankle jerk
How are deep tendon stretch reflexes examined?
A tendon hammer is used to apply a brief, sudden stretch to the muscle via its tendon
What is the normal reflex response to being stretched
Contraction
Reflex contraction results in a brief twitch of the muscle____ or a movement in the normal direction
belly
Describe a Tendon Reflex
Sensory nerve from muscle detects stretch - tells spinal cord - synapse between sensory & motor nerves - motor nerve signals muscle to contract
At which synapse does the motor nerve communicate with the skeletal muscle?
The Neuromuscular junction
How is it prevented that the deep tendon reflex is overly brisk?
“Descending controls” from the brain
A normal stretch reflex indicated that (4) are functioning normally
- muscle & its sensory and motor nerve fibres
- Spinal cord connections
- Neuromuscular junction
- Descending controls form the brain
What does Paralysis indicated?
A muscle without a functioning motor nerve supply, i.e. the muscle cannot contract
What would a paralysed muscle show on examination?
Reduced tone
What does Spasticity indicate?
That the muscle has an intact and functioning motor nerve but the descending controls from the brain are not working
What would a spastic muscle show on examination?
Increased tone
What is atrophy?
Wasting of the muscles, i.e. the muscle fibres become smaller, reducing the muscle’s bulk
Atrophy develops as a result of…
Inactivity
What is hypertrophy?
Increase in cell size (opp. of atrophy)
What makes up the muscle compartments of the lower limb?
Thigh (anterior, medial and posterior compartments)
Leg (anterior, posterior and lateral compartments)
What makes up the muscle compartments of the upper limb?
Arm (anterior & posterior compartments)
Forearm (anterior & posterior compartments)
What is compartment syndrome?
Increased pressure in the fascial compartments caused by swelling of tissue or increase in fluid (bleeding), affecting functions of the muscles or nerves in the compartment - can be acute or chronic
What is a fasciotomy?
Procedure where fascia are cut to relieve pressure in an emergency for a patient presenting with acute compartment syndrome
Muscles that perform the protective reflexes of coughing, gagging, swallowing & vomiting are all ____ muscles of the proximal respiratory/alimentary tracts
Skeletal
Muscles that control micturition (urine passing) and defecation are ____ muscle
Skeletal
Where do which transition of smooth/skeletal muscle take place
Skeletal to smooth at the trachea and back to skeletal in the perineum
