Principles - Muscles and Movement

Question 1

What are the three different types of muscle?

Answer 1

Cardiac (involuntary and striated)
Smooth (involuntary and non striated)
Skeletal (voluntary and striated)

Question 2

What is the structure of a muscle?

Answer 2

One big muscle is made up of lots of little bundles - fascicles

Fascicles are also made up of lots of little bundles - muscle fibre

Muscle fibre is made up of lots of little bundles - myofibril

Myofibril is made from many actin and myosin microfilaments

Question 3

What are the different shapes skeletal muscles can be?

Answer 3

Quadrate - 4 equal side e.g. rectus abdominus

Fusiform - spindle shaped, tapers off at either end e.g. biceps brachii

Pennate - feather shaped e.g. deltoid

Question 4

How do muscles move a joint?

Answer 4

They can only one a joint if they span it i.e. they have to cross the joint and attach to bones on either side

Question 5

What are tendons?

Answer 5

These are found at either end of the muscle and attach the muscle to bone

Question 6

What is an aponeurosis?

Answer 6

A flattened tendon, mostly associated with flat muscles - attach muscle to soft tissue rather than bone

Question 7

How many attachments to bone do tendons have?

Answer 7

Usually at least 2
Origin - on one side of the joint
Insertion - on the other side

Question 8

What does direction of movement of a muscle depend on?

Answer 8

On which side of the joint the muscle spans
e.g. biceps brachii -
spans the anterior shoulder joint, therefore flexes the shoulder joint
spans the anterior elbow joint therefore it flexes the elbow joint
spans the anterior proximal radioulnar joint producing supination of the forearm

Question 9

How does the deltoid muscle cause 3 different movements in the shoulder joint?

Answer 9

It only crosses one joint, however it has muscle fibres that go in different directions
3 different origins but one insertion means there will be more than one movement

Question 10

What three movements can the deltoid produce?

Answer 10

posterior fibres: extension of the shoulder
middle fibres: abduction of the shoulder
anterior fibres: flexion of the shoulder

Question 11

What determines possible movement?

Answer 11

The shape of the articular surface

e.g. trochlear notch of the proximal ulna/ trochlea of the detail humerus = only flexion/extension

Question 12

What are reflexes?

Answer 12

Rapid, predictable, involuntary reactions to ‘danger’ - protective
Movement made unconsciously

Question 13

What are the 2 main reflexes involving skeletal muscles?

Answer 13

Stretch reflex

Flexion withdrawal reflex (when we touch something potentially damaging, sudden flexion to withdraw from the danger

Question 14

What part of the CNS is involved in reflexes?

Answer 14

Spinal cord

Brian is NOT involved

Question 15

What is the normal reflex response to being stretched?

Answer 15

Contraction

Reflex contraction results in a brief twitch of the muscle belly or a movement in the normal direction

Question 16

Describe the process of stretch reflex.

Answer 16

• sensory nerve from muscle detects stretch and tells spinal cord
• synapse in the spinal cord between sensory and motor nerves
• motor nerve from spinal cord passes message to muscle to contract
• the whole route taken by the action potential is called the reflex arc

Question 17

What is muscle paralysis?

Answer 17

A muscle without a functioning motor nerve supply is paralysed - can’t contract

Question 18

What is muscle spasticity?

Answer 18

The muscle has an intact and functioning motor nerve. The descending controls from the brain are not working.

Question 19

What is tonic contraction?

Answer 19

Muscles are always a little bit contracted - not enough to move the muscle, just enough so that if you need to contract the muscle you can

Question 20

What is muscle atrophy?

Answer 20

Wasting of the muscles
Myocytes become smaller
Develops has a result of inactivity

Question 21

What is muscle hypertrophy?

Answer 21

Opposite to atrophy

Myocytes become enlarged

Question 22

Where are skeletal muscles usually found?

Answer 22

Deep to deep fascia

Question 23

What is a muscle compartment?

Answer 23

Sections within the body that contains muscles and nerves and are separated by inter muscular septums
e.g. the thigh has 3 compartments - anterior, medial and posterior

Question 24

What is the inter muscular septum?

Answer 24

An extension of the deep fascia, splitting the muscles in the limbs into different compartments