The principles of the Muscular System

Question 1

How are muscle cells arranged?

Answer 1

Muscle cells lie in parallel arrays. They are elongated in the axis of contraction

Question 2

What are the different types of Muscles? (3)

Answer 2

Skeletal - Voluntary - Striated
Cardiac - Involuntary - Striated
Smooth - involuntary - Striated

Question 3

How does the activity differ between the 3 different muscle types?

Answer 3

Skeletal muscle has strong, quick discontinuous voluntary contraction
Cardiac muscle has strong quick continuous involuntary contraction
Smooth muscle has weak slow involuntary contraction.

Question 4

What are the 3 functions of skeletal muscle?

Answer 4

Moving organs and structures
Posture
Voluntary muscle

Question 5

What are the features of skeletal muscles?

Answer 5

They are supplied by the spinal and cranial nerves
Attached to the bones move the joints the cross

Question 6

What are the features of muscle fibres?

Answer 6

cylindrical, cross striated, multinucleated

Question 7

Draw a diagram of a muscle fibre.

Answer 7

Question 8

Describe the microstructure of muscles. And label the diagram

Answer 8

• Elongated, multinucleated cells
• Peripheral nuclei
• Grouped into bundles called fascicles
• Surrounded by connective tissue:

Epimysium - muscle

Perimysium - fascicle

Endomysium - fibre

Question 9

What are cross striations and how do they come about?

Answer 9

These are the alternating pattern of dark and light bands.

This is due to the myofibrils. These are made up of myofilament.

There are two types of myofilaments. Thin actin filaments(light band ) and thick myosin (dark filaments).

Question 10

What are satellite cells?

Answer 10

These are the cells responsible for muscle cell repair.

Question 11

What are the 4 parameters when describing muscle?

Answer 11

1. Origin
2. insertion
3. function
4. innervation

Question 12

Pectoralis major OIFI

Answer 12

Origin: Clavicle, sternum and costal cartilages

Insertion: Humerus

Function: Flexion, adduction and internal rotation of the shoulder joint

Innervation: Lateral and Medial Pectoral nerve

Question 13

Pectoralis minor OIFI

Answer 13

O: Ribs 3, 4 and 5

I: Corocoid process of the scapula

F: Draws scapula anteriorly, inferiorly and medially, Elevates the ribs

I: Medial Pectoral nerve

Question 14

Biceps Brachii OIFI

Answer 14

O: Long Head - supraglenoid tubercle of the scapula. Short Head coracoid process of the scapula

I: Radius

F: Flexion of the shoulder joint, Flexion of the elbow joint, Supination of the radio-ulnar joints

I: Musculocutaneous nerve

Question 15

Deltoid OIFI

Answer 15

O: Clavicle, acromion and Spine of the scapula

I: Deltoid tuberosity of the humerus

F: Abduction of the shoulder joint

I: Axillary nerve

Question 16

Serratus anterior OIFI

Answer 16

O: Upper 8/9 Ribs

I: Scapula

F: Protraction of the scapula, Holds scapula flat against the thoracic cage

I: Long Thoracic nerve

Question 17

What are the 6 types of muscle fibre arrangements? Describe them.

Answer 17

Flat: All muscle fibres arranged along a plane.

Pennate: Two or more fibres going in different directions that converge if a single tendon

Fusiform: spindle-shaped

Quadrate: It has four different fibre sides.

Circular: Fibres are arranged in a circle and converge on a single tendon.

Multibelleied/ headed: Fibers come from the same tendon but split off in different directions.

Question 18

Give examples of the 6 different types of muscle fibres in the human body.

Answer 18

Flat - Abdominal and external obliques

Pennate - Deltoid

Fusiform - Bicep braccii

Quadrate - The quadriceps

Circular - Orbicularis ocul

Multi-headed - Bicep Brachii