Lecture: Anatomy 1: Principles of the muscular system

Question 1

What are the 3 types of muscle?

Answer 1

1. Skeletal/ voluntary / striated muscle
2. Cardiac/ involuntary / striated muscle
3. Smooth / involuntary / non-striated muscle

Question 2

What is skeletal muscle responsible for?

Answer 2

Responsible for moving organs/structures, maintaining posture, and voluntary movement.

Question 3

What is the skeletal muscle supplied by?

Answer 3

Spinal and cranial nerves

Question 4

Describe the structure of skeletal muscle fibres

Answer 4

Muscle fibres are cylindrical, cross striated, and multinucleated. Skeletal muscle cells are grouped into bundles called fascicles which are surrounded by connective tissue.

Question 5

Where is cardiac muscle found?

Answer 5

Found only in the myocardium and in the walls of large blood vessels joining the heart.

Question 6

What is the cardiac muscle supplied by?

Answer 6

Supplied by autonomic nerve fibres

Question 7

Describe the structure of cardiac muscle fibres

Answer 7

Muscle fibres are short and branching with a central nucleus. Two muscle fibres meet at their ends by an intercalated disc.

Question 8

What are intercalated discs?

Answer 8

Areas of cell adhesion between adjacent cardiac muscle cells which permit rapid spread of contractile stimuli from one cell to another

Question 9

Describe the structure of smooth muscle fibres

Answer 9

Muscle fibres are spindle shaped with central nucleus.

Question 10

Where is smooth muscle found?

Answer 10

Found in various organs and blood vessels

Question 11

What is the smooth muscle supplied by?

Answer 11

Supplied by the autonomic nerve fibres from sympathetic trunk

Question 12

What is the epimysium?

Answer 12

The connective tissue around a muscle cell

Question 13

What is the perimysium?

Answer 13

The connective tissue around fascicle (bundle of muscle cells)

Question 14

What is the endomysium?

Answer 14

The connective tissue all around the muscle fibre

Question 15

Describe the structure of the sarcomere

Answer 15

Sarcomere composed of thick filaments (MYOSIN; dark band) and thin filaments (ACTIN; light band).

Question 16

Pectoralis Major

Answer 16

Origin: clavicle, sternum and costal cartilages
Insertion: Humerus
Action: flexion, adduction and internal rotation of shoulder joint
Nerve supply: lateral and medial pectoral nerves

Question 17

Pectoralis Minor

Answer 17

Origin: Ribs 3,4, and 5
Insertion: Corocoid process of scapula
Action: elevates ribs and moves scapula anteriorly, interiorly and medially
Nerve supply: medial pectoral nerves

Question 18

Biceps Brachii

Answer 18

Origin: long head attaches to tubercle of scapula and short head attaches to coracoid process of scapula
Insertion: Radius
Action: flexion of shoulder and elbow, supination of ulnar-radio joint
Nerve supply: Musculocutaneous nerve

Question 19

Deltoid

Answer 19

Origin: clavicle, acromion and spine of scapula
Insertion: deltoid tuberosity of humerus
Action: abduction of shoulder
Nerve supply: axillary nerve

Question 20

Serratus Anterior

Answer 20

Origin: ribs 1-8/9
Insertion: scapula
Action: protraction of the scapula
Nerve supply: long thoracic nerve

Question 21

How is muscle contraction stimulated?

Answer 21

Muscle contraction is stimulated by motor nerves at the neuromuscular junction which release acetylcholine. Calcium released from the sarcoplasmic reticulum causes contraction.

Question 22

What component aids in the simultaneous contraction of muscle cells?

Answer 22

Sarcolemma with T-tubules

Question 23

What are satellite cells?

Answer 23

Myogenic cells located between the sarcolemma and basement membrane of muscle fibres that allow for muscle regeneration.