W7: Properties Of Skeletal Muscles

Question 1

What are the 4 general classes of tissue?

Answer 1

Epithelial tissue, nervous tissue, muscle tissue, connective tissue

Question 2

What are the general classes of muscle tissue in the body?

Answer 2

Striated and non-striated

Voluntary and involuntary control

Question 3

What muscles are striated and what muscles are non-striated?

Answer 3

Striated - skeletal and cardiac

Non-striated - smooth

Question 4

What nervous system is skeletal muscle under?

Answer 4

Somatic nervous system. Voluntary control.

Question 5

What is a motor unit?

Answer 5

A motor neurone, the NMJ and the muscle fibre it innervates

Question 6

What are the roles of skeletal muscle?

Answer 6

Movement, posture, stability of joints, heat generation

Question 7

What is the endomysium?

Answer 7

Tissue sheath enveloping a muscle fibre

Question 8

What is the perimysium?

Answer 8

Tissue sheath enveloping a fascicle

Question 9

What is the epimysium?

Answer 9

Tissue sheath enveloping all fascicles of a muscle.

Question 10

Where do nerves and blood vessels run that supply skeletal muscles?

Answer 10

Nerves and blood vessels of any muscle run in between and in parallel muscle fascicles

Question 11

What 3 ways can skeletal muscle attach to bone or skin directly through?

Answer 11

Fleshy interactions: direct muscle attachment to target
Tendon: thickened organised fibrous connective tissue assembly at the end of a muscle
Aponeurosis: flattened tendon

Question 12

What is the structure of single muscle fibres?

Answer 12

Long multinucleated muscle cells, with nuclei on the periphery of the cells.

Question 13

What does health of the muscle depend on?

Answer 13

Sufficient nerve and blood supply
Each skeletal muscle has a nerve ending that controls its activity (innervation) and an individual system to supply and drain blood (vascularisation)

Question 14

What are myofibrils made of?

Answer 14

Thick myosin and thin actin filaments

Question 15

What is a tendon?

Answer 15

An organised tough band of fibrous connective tissue mass that forms a point of confluence of contract (pull) by single myocytes of a muscle

Question 16

What are the two variants of tendons?

Answer 16

A tendon of origin

A tendon of insertion

Question 17

What is a tendon of origin?

Answer 17

Attachment of muscle that anchors the muscle as it displaces during movement. Origin=fixed.

Question 18

What is a tendon of insertion?

Answer 18

Attachment of the muscle that is displaced in order for movement to occur. Insertion = moves.

Question 19

What happens to tendons of origins and insertions in bi-articular muscles?

Answer 19

They can change depending on which movement is commanded at the time.

Question 20

What are pairs of muscles acting on a common joint called?

Answer 20

Agonist-antagonist pair, or antagonist pair

Question 21

How are members of the antagonist pair innervated?

Answer 21

Members of the antagonist muscle pair receive motor supply from alpha motoneurones that have reciprocal connections from the spinal cord. This ensures that for any muscle pair, when one muscle or set of muscles contracts, the other relaxes and vice versa.

Question 22

How do muscles in the antagonist pair act?

Answer 22

One muscle acts as a flexor (a muscle that bends a joint, reducing the angle subtended at the joint) and another acts as an extensor (a muscle that straightens a joint, increasing the angle subtended at the joint)

Question 23

What happens if a muscle fibre loses its motor nerve supply?

Answer 23

It becomes denervated

Question 24

What categories can muscle fibres be classified into according to how quickly they develop force and how long they take to relax?

Answer 24

Slow - develop over a long time and remain over a long time (do not fatigue)
Intermediate
Fast - fast at developing force but fatigue easily, e.g., eyes

Question 25

How are jerky movements prevented?

Answer 25

A stimuli has to be more frequent and cause a summation of twitches to produce a tetanus. Summary by reducing the internal between stimuli.

Question 26

What is a ‘nerve entry point’ or neurovascular hilum?

Answer 26

Site of entry of a motoneurons into the muscle
Site of exit of venous drainage of the muscle
Site of entry of arterial supply to muscle
Site of aggregation of nicotinic receptors of healthy muscles