1What are the two learning objectives of the lecture “Introduction to muscles”?
1. Classify the muscles with examples. 2. Explain/outline the parts of skeletal muscles.
2How are muscle cells (fibres) formed?
Muscle cells are formed by fusion of 100+ myoblasts, which are small mesodermal cells.
3What is the end result of fusion of myoblasts?
A multinucleate muscle cell (muscle fibre).
4What is hypertrophy?
Enlargement of existing muscle fibres.
5What causes muscle hypertrophy?
Forceful, repetitive muscular activity, resulting in increased production of myofibrils and organelles.
6What are the two types of muscle hypertrophy mentioned in the lecture?
Sarcoplasmic hypertrophy and myofibrillar hypertrophy. Introduction to muscles.pdf
7What happens to muscle cell division once maturity is reached?
Cell division is not possible. Introduction to muscles.pdf
8What are the three types of muscular tissue?
Skeletal muscle, cardiac muscle and smooth muscle. Introduction to muscles.pdf
9What percentage of body weight is formed by skeletal muscle according to the lecture?
42% of body weight. Introduction to muscles.pdf
10Is skeletal muscle voluntary or involuntary?
Skeletal muscle is voluntary, although some actions are automatic, such as stretch reflexes. Introduction to muscles.pdf
11How do skeletal muscles produce movement?
They produce movement by shortening and by exerting force on tendons, which pull on bones or other structures such as skin. Introduction to muscles.pdf
12What is the Achilles tendon?
The tendocalcaneous/Achilles tendon is a long tendon of collagenous fibres at the end of a skeletal muscle. Introduction to muscles.pdf
13What is an aponeurosis?
A flat sheet of white fibrous tissue by which a muscle can be attached. Introduction to muscles.pdf
14What is the fleshy part of a skeletal muscle called?
The muscle belly, which is the contractile part. Introduction to muscles.pdf
15What do most skeletal muscles cross?
Most muscles cross at least one joint and are usually attached to the articulating bones that form the joint. Introduction to muscles.pdf
16What are the four main features used to describe skeletal muscles?
Origin, insertion, nerve supply (innervation), and actions. Introduction to muscles.pdf
17What is the origin of a muscle?
The proximal attachment of the muscle. Introduction to muscles.pdf
18What is the insertion of a muscle?
The distal attachment of the muscle. Introduction to muscles.pdf
19What type of tissue usually forms muscle attachments?
Tendinous tissue. Introduction to muscles.pdf
20What are muscle attachments called when the origin is from more than one bone?
Heads. Introduction to muscles.pdf
21Give examples of muscles named according to the number of heads of origin.
Biceps has two heads, triceps has three heads, and quadriceps has four heads. Introduction to muscles.pdf
22What is a prime mover (agonist)?
A muscle that produces most of the force in a particular action. Introduction to muscles.pdf
23What is a synergist?
A muscle that aids the prime mover. Introduction to muscles.pdf
24What are the additional functions of a synergist?
It may stabilize a joint, restrict certain movements, or modify the direction of a movement. Introduction to muscles.pdf
25What is an antagonist?
A muscle that opposes the prime mover. Introduction to muscles.pdf
26How does an antagonist commonly control movement?
It maintains some tension on a joint, limiting the speed and range of the prime mover. Introduction to muscles.pdf
27How does an antagonist help prevent injury?
It prevents excessive movement, joint injury, or inappropriate actions. Introduction to muscles.pdf
28What may happen when an antagonist relaxes during an action?
It gives the prime mover almost complete control over the action. Introduction to muscles.pdf
29What is a fixator?
A muscle that prevents a bone from moving. Introduction to muscles.pdf
30How does a fixator assist another muscle?
It holds a bone steady, allowing another muscle attached to it to pull on something else. Introduction to muscles.pdf
31What factors can be used in naming muscles?
Shape, number of heads of origin, gross structure, location, attachments, action, relative size, and direction/orientation of muscle fibres or cells. Introduction to muscles.pdf
32How are biceps, triceps and quadriceps named according to their number of origins?
Biceps = two heads; triceps = three heads; quadriceps = four heads. Introduction to muscles.pdf
33Give examples of muscles named according to their action.
Flexor carpi radialis, extensor carpi radialis, abductor pollicis brevis, adductor pollicis, adductor magnus, and extensor digitorum. Introduction to muscles.pdf
34What are examples of muscles named according to their location?
Frontalis, temporalis and occipitalis. Introduction to muscles.pdf
35What are the five types of muscles named based on fascicular architecture?
Parallel fasciculus, pennate fasciculi, convergent fasciculus, twisted or spiral fasciculi, and circular (sphincteric). Introduction to muscles.pdf
36What are the seven fascicular arrangements shown in the lecture?
Circular, convergent, strap, unipennate, multipennate, parallel, and bipennate. Introduction to muscles.pdf
37What is muscle tone?
A partial state of contraction of a muscle during rest that maintains a constant muscle length. Introduction to muscles.pdf
38What is the resting tension produced by muscle tone called?
Muscle tone. Introduction to muscles.pdf
39What is disuse atrophy?
Shrinking of muscles due to a lack of use or physical activity. Introduction to muscles.pdf
40When can disuse atrophy occur?
After injury, during prolonged bed rest, or from inactivity. Introduction to muscles.pdf
41What is myositis?
Muscle inflammation. Introduction to muscles.pdf
42What is myalgia?
Muscle pain due to overstretching or tearing of muscle fibres. Introduction to muscles.pdf
43What is a muscle spasm?
A sudden involuntary contraction in which a muscle involuntarily and forcibly contracts uncontrollably and cannot relax. Introduction to muscles.pdf
44What is the motor point?
The site where the motor nerve enters the muscle. Introduction to muscles.pdf
45What is a motor unit?
A single motor neuron together with the muscle fibres supplied by it. Introduction to muscles.pdf
46What determines the size of a motor unit?
The precision of the movement. Introduction to muscles.pdf
47How does motor unit size relate to precision of movement?
More precision → fewer muscle fibres per motor unit; less precision → more muscle fibres per motor unit. Introduction to muscles.pdf
48What are the two components of skeletal muscle tissue in its structural organization?
A parenchyma of muscle cells (fibres) and a stroma of connective tissue. Introduction to muscles.pdf
49What are the three connective tissue coverings of skeletal muscle?
Epimysium, perimysium and endomysium. Introduction to muscles.pdf
50What does the epimysium cover?
The whole skeletal muscle. Introduction to muscles.pdf
51What does the epimysium form by extending inwards?
It forms perimysium and groups muscle fibres into bundles called fasciculi. Introduction to muscles.pdf
52What does the perimysium surround?
Each fasciculus. Introduction to muscles.pdf
53What does the perimysium become by extending inwards?
It becomes endomysium. Introduction to muscles.pdf
54What does the endomysium surround?
Each individual muscle cell (fibre). Introduction to muscles.pdf
55What is the correct sequence of connective tissue coverings from the whole muscle to an individual muscle fibre?
Epimysium → perimysium → endomysium. Introduction to muscles.pdf
56What happens to the connective tissue coverings at the ends of the muscle?
They extend beyond the fleshy muscle belly at both ends to continue as tendons or aponeuroses. Introduction to muscles.pdf
57What are the functions of the connective tissue coverings of skeletal muscle?
They provide passageways for blood vessels and nerves, and support and protect muscle fibres so they can withstand the force of contraction. Introduction to muscles.pdf