Muscles and Movement Flashcards by Jonas Repkewitz

What are the 3 types of muscle?

Cardia (involuntary &amp; striated)
Smooth Muscle (involuntary &amp; non-striated)
Skeletal Muscle (voluntary &amp; striated)

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What is a sarcomere?

The repeating unit between two Z-lines

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What is the sequence of skeletal muscle structure

Skeletal muscle - Fascicles - Muscle fibres - Myofibrils - Actin & Myosin microfilaments

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Why does skeletal muscle look ‘striped’ when viewed histologically?

Overlapping actin & myosin

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What happens at a histological level when a skeletal muscle is “strained” / “pulled”?

Some of the muscle fibres are torn

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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

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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

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During contraction, skeletal muscles….

shorten

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Muscles (usually) attach to bone via…

tendons

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What is an aponeurosis?

A flattened tendon

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What are flattened tendons most commonly associated with?

Flat muscles

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What are the points of attachment of a muscle to a bone called

Origins and insertions

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The only thing a skeletal muscle can do is…

contract, i.e. muscle fibres shorten along the long axis between the origin and insertion

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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

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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

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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

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Usually skeletal muscles are named according to a combination of…

shape / location / size / main bony attachment / main movement

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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

1. muscle & its sensory and motor nerve fibres 2. Spinal cord connections 3. Neuromuscular junction 4. 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