Muscular System and Muscles

Question 1

Types of Muscle

Answer 1

Skeletal: attaches and covers skeleton

• voluntary
• cylindrical multinucleate cells with striations

Smooth: in walls of hollow organs, involuntary (controlled by ANS)
- single, fusiform, uninucleate, no striations

Cardiac: involuntary
- branching chains of striated cells that are uni or bi-nucleate

Question 2

Skeletal Muscle

Answer 2

~700

1. Muscle: individual cells, blood vessels and nerves wrapped via epimysium
2. Fascicle: bundle of muscle cells wrapped in perimysium
3. Fibre: individual muscle cells wrapped in endomysium

Question 3

Patterns of Fascicle Arrangement

Answer 3

muscles can only contract in direction of fascicles

1. Circular: concentric rings (eg: sphincters)
2. Convergent: broad origin with fascicles converging towards a single tendon of insertion (eg: pectoralis major)
   - strongest contraction
3. Parallel: length of fascicles runs parallel to long axis of muscle
   - greatest shortening of length during contraction
4. Pennate: short fascicles that attach obliquely
   - Unipennate: fascicles insert onto only one side of tendon (eg: extensor digitorum longus)

• bipennate: inserts onto tendon from opposite sides (looks like a feather - eg: rectus femoris)
• multipennate: inserts onto tendon from many directions (eg: deltoid)

Question 4

Ligaments

Answer 4

• fibrous connections b/w bones (connects bone - bone)
• composed of collagen fibres
• usually blend w periosteum of bones at the joint

Question 5

Tendon

Answer 5

• fibrous tissue linking muscle belly to bone

- allows bone to move when muscle moves

Question 6

Aponeurosis

Answer 6

broad, flat connective tissue that links muscle belly –> site of attachment

Question 7

Raphe

Answer 7

line of fibrous tissue joining one muscle to another

Question 8

Prime Mover

Answer 8

Main muscle responsible for producing concentric contraction (force>gravity)
- eg: biceps brachii = prime mover of elbow flexion

Question 9

Synergist

Answer 9

compliments action of prime mover by adding extra force and reducing undesirable/unnecessary movement
- brachialis = synergist of biceps

Question 10

Antagonist

Answer 10

muscle that opposes action of prime mover (eccentric )

• regulates action of PM by providing resistance to slow movement
• eg: Triceps brachii

Question 11

Fixator

Answer 11

steadies proximal parts of a limb whilst movements occur in distal parts (isometric)
- eg: rotator cuff muscles stabilise shoulder during elbow flexion

Question 12

A muscle crossing the ANTERIOR side of a joint produces

Answer 12

FLEXION

Question 13

A muscle crossing the POSTERIOR side of a joint produces

Answer 13

extension

Question 14

A muscle crossing the lateral side of a joint produces

Answer 14

abduction

Question 15

A muscle crossing the medial side of a joint produces

Answer 15

adduction

Question 16

Fascia

Answer 16

connective tissue that wraps, packages and insulates deep structures

Superficial: loose, subcutaneous tissue

Deep: thin, rough sheet made mostly of collagen fibres
- strong, inelastic and usually single layer

Fascial septum: extension of dense connective tissue

Retinaculum: thickening of deep fascia that holds down tendons