Principles of Muscle System

Question 1

Draw a label a muscle (5)

Answer 1

1. Epimysium
2. Perimysium
3. Blood Vessels and nerves
4. Fascicles
5. Muscle Fibres

Question 2

What are the 3 types of muscle? (3)

Answer 2

1. Skeletal Muscle - Quick discontinuous Voluntary contrition and striated muscle
2. Cardiac Muscle - Quick continuous Involuntary contraction and striated muscle
3. Smooth Muscle - Weak, slow Involuntary contraction and non-straited

Question 3

What are the functions of Skeletal Muscle? (3)

Answer 3

1. Organ and structural movement
2. Posture
3. Voluntary Movement of bone/joint by contraction of muscle fibres through shortening of the sarcomere; and shortening between origin and insertion

Question 4

What are the features of the skeletal muscle? (3)

Answer 4

1. They are supplied by the spinal and cranial nerves
2. Attached to bones and move at the joints they cross
3. Muscle Fibres are cylindrical, cross striated and nucleated

Question 5

What are the microstructures of the skeletal muscle? (4)

Answer 5

1. Elongated, multinucleated cells
2. Peripheral nuclei
3. Grouped into fascicles
4. Surrounded by connective tissue - Epimysium (muscle), Perimysium (fascicle), Endomysium (fibre)

Question 6

What is a Muscle fibre made up of? (4)

Answer 6

Myofibrils->Myofilaments-> sacomere->Myosin (thick dark filaments), Actin (thin light filaments)

Question 7

Biceps brachii. State Origin, insertion, Action and Nerve supply (4)

Answer 7

Origin: Long head attaches to Supraglenoid tubercle of the scapula. Shorthead attaches to the corocoid process of the scapula

Insertion: Radius

Action: Flexion of shoulder and elbow joint. Supination of the radio-ulnar joints

Nerve Supply: Musculocutaeneous Nerve

Question 8

Deltoid. State origin, Insertion, Action and Nerve Supply (4)

Answer 8

Origin: Clavicle, acromion process, and spine of the scapula
Insertion: Deltoid Tuberosity of the humorous
Action: Abduction of the shoulder joint
Nerve Supply - Axillary Nerve

Question 9

What are the different forms of muscle arrangement? (7)

Answer 9

1. Flat e.g External Oblique
2. Circular - e.g Orbicularis Oculi
3. Pennate e.g Deltoid
4. Fusiform
5. Quadrate
6. Multiheaded/bellied - Biceps

Question 10

How is contraction controlled in the muscles?

Answer 10

1. Release of Acetylcholine at neuromuscular junctions to stimulate motor nerves
2. Calcium Relase from Sarcoplasmic Reticulum causes contraction.

The Sarcolemma with T-tubules allows simultaneous contraction.

Question 11

Why and how do Skeletal Muscles Regenerate? (3)

Answer 11

1. Through Satellite (myogenic) cells between sarcolemma and basement membrane of the muscle fibres.
2. Act as reserve cell population
3. These are normally dormant in adult muscle, but proliferate in response to injury, regenerating muscle cells and making more satellite cells.

Question 12

What nerve supplies the cardiac muscle? (1)

Answer 12

Vagus Nerve .

Question 13

What are the features of the cardiac muscle? (3)

Answer 13

1. Cross Striated
2. Short and branching muscle fibres with intercalated discs (appear dark and irregular)
3. Nucleus is central

Question 14

What are the functions of the intercalated discs in cardia muscles? (2)

Answer 14

1. They maintain cohesion between adjacent muscle cells.

2. Permit rapid spread of contractile stimuli from one cell to another.

Question 15

What nerve system supplies the Smooth Muscle (1)

Answer 15

Autonomic nerve fibres

Question 16

What are the microstructures of the smooth muscle? (3)

Answer 16

1. Wide Central and oval nucleus

2. Muscle fibre is spindle shaped and elongated.