[L3 Anatomy and Physiology] Section 2: The musculoskeletal system

Question 1

Explain the cellular structure order of skeletal muscle, starting from the Epimysium.

Answer 1

Epimysium, Perimysium, Fasculi, Endomysium, Muscle Fibres, Myofibril, Myofilaments (actin/myosin).

Question 2

What is the Epimysium?

Answer 2

The tough membrane that surrounds the whole muscle belly and holds the smaller fasciculi
units together.

Question 3

What is the Perimysium?

Answer 3

The membrane which surrounds the bundles of muscle fibres (the fasciculi).

Question 4

What is the Endomysium?

Answer 4

The membrane that surrounds the individual muscle fibres, which contain the myofibrils.

Question 5

What is a Tendon?

Answer 5

Tough, inelastic fibres which wrap around the end of the muscle and attach it to the outer layer
of the bone.

Question 6

What is the Myofibril?

Answer 6

The smallest unit, or fibril, within the individual muscle fibers.

Question 7

What is the Myofilaments?

Answer 7

The contractile proteins myosin and actin arranged within compartments in the myofibril
called sarcomeres.

Question 8

The power to drive the myosin head in the sliding filament theory is what molecule?

Answer 8

ATP.

Question 9

How does the ATP molecule prime the myosin for activity?

Answer 9

By binding and transferring energy with the head.

Question 10

Although the myosin head may have been primed with energy from the ATP, it will be unable to bind with the
actin without the presence of what element in the body and why?

Answer 10

Calcium - In a relaxed state, the myosin-binding sites on the actin are blocked by a combination of other molecules (troponin and tropomyosin) and Calcium causes the blocking molecule to move away from the myosin binding site (thus allowing the
‘primed’ myosin head to bind with the actin)

Question 11

What are some structural features of slow twitch/type 1 muscle fibres?

Answer 11

• Smaller diameter fibre size
• Large myoglobin content
• Many mitochondria (cells where aerobic energy is produced)
• Many capillaries to deliver blood and oxygen
• Red in colour

Question 12

What are some functional features of slow twitch/type 1 muscle fibres?

Answer 12

• Increased oxygen delivery
• Produce less force
• Long-term contractions
• Resistant to fatigue
• Aerobic

Question 13

What are some structural features of fast twitch/type 2 muscle fibres?

Answer 13

• Larger diameter fibre size
• Smaller myoglobin content
• Fewer mitochondria
• Fewer capillaries
• White (pale) in colour

Question 14

What are some functional features of fast twitch/type 2 muscle fibres?

Answer 14

Decreased oxygen delivery
• Produce more force
• Short-term contractions
• Less resistant to fatigue
• Anaerobic

Question 15

Explain the four main stages of the sliding filament theory.

Answer 15

COCKING PHASE:ATP is broken down, releasing energy to prime the myosin head into a ‘cocked’ position.

BINDING PHASE: Calcium ions are released from the SR and allow the myosin head to attach to the actin binding sites.

POWER STROKE: The myosin head rotates, pulling the actin towards the centre of the sarcomere to generate tension/muscle contraction.

RE-SETTING: ATP binds to the myosin head, releasing it from the actin binding site.

Question 16

What are some effects aerobic/endurance exercise has on Type 1 and Type 2a/2b muscle fibres.

Answer 16

Type I or type IIa fibre changes:
• Improved efficiency and work capacity.
• Increased number and size of mitochondria.
• Hypertrophy.
• Increased aerobic enzyme levels.
• Increased capillary density.

No change to type IIb fibres.

Question 17

What are some effects anaerobic, heavy resistance exercise has on Type 1 and Type 2a/2b muscle fibres.

Answer 17

Type IIa and IIb fibre changes:
• Increase in anaerobic enzyme levels.
• Increased phosphocreatine stores.
• Hypertrophy.
• Increased contractile protein density.

No change to type I fibres except hypertrophy.

Question 18

What is the frontal plane?

Answer 18

A vertical plane that divides the body into anterior

and posterior parts.

Question 19

What is the saggital plane?

Answer 19

A vertical plane that divides the body into left and

right parts.

Question 20

What is the transverse plane?

Answer 20

A horizontal cross-section through the body which

separates the upper and lower body

Question 21

What is an axis, and at what angle is the axis of each plane associated with.

Answer 21

A theoretical point around which rotation occurs passes through each plane at right angles.

Question 22

Which axis passes through the frontal plane?

Answer 22

The anterior-posterior axis

Question 23

Which axis passes through the sagittal plane?

Answer 23

The medial-lateral axis

Question 24

Which axis passes through the transverse plane?

Answer 24

The longitudinal axis

Question 25

Whats plane and axis does a squat take place in?

Answer 25

Sagittal & Medial-lateral

Question 26

Whats plane and axis doe side-stepping place in?

Answer 26

Frontal & Anterior-posterior

Question 27

Whats plane and axis does throwing a ball take place in?

Answer 27

Transverse & Longitudinal

Question 28

Name the three types of joints

Answer 28

FIBROUS, CARTILAGINOUS & SYNOVIAL

Question 29

Name the 6 types of synovial joints and give an example of each

Answer 29

* Gliding joints, e.g. the mid-carpal and mid-tarsal bones of the wrist and ankle. * Pivot joints, e.g. between the atlas and axis of the cervical vertebrae. * Saddle joints, e.g. the thumb. * Ball and socket joints, e.g. the hip and shoulder. * Ellipsoid joints, e.g. the knuckles between the phalangeal bones of the fingers and toes. * Hinge joints, e.g. the knee and elbow.

Question 30

Plane of movement and axis for: Shoulder - Flexion/Extension

Answer 30

Sagittal & Medial-Lateral axis

Question 31

Plane of movement and axis for: Shoulder - Ab/Aduction

Answer 31

Frontal & Anterior-Posterior axis

Question 32

Plane of movement and axis for: Shoulder - Internal/External Rortation

Answer 32

Transverse & Longtuidinal

Question 33

Plane of movement and axis for: Elbow - Flexion/Extension

Answer 33

Sagittal & Medial-Lateral axis

Question 34

Plane of movement and axis for: Spinal - Flexion/Extension

Answer 34

Sagittal & Medial-Lateral axis

Question 35

Plane of movement and axis for: Spinal - Lateral Flexion

Answer 35

Frontal & Anterior-Posterior axis

Question 36

Plane of movement and axis for: Spinal - Rotation

Answer 36

Transverse & Longtuidinal

Question 37

What do the rotator cuffs do, and where do they orginate and insert?

Answer 37

Stabilize and control movement at the shoulder joint. They originate from the scapula and inserts on the upper aspect of the humerus.

Question 38

Name the four rotator cuff muscles

Answer 38

Teres minor, supraspinatus, infraspinatus & subscapularis

Question 39

Where does the Teres minor run, and what joint movement does it help with?

Answer 39

This runs laterally from the scapula to the humerus and helps with adduction and external rotation.

Question 40

Where does the supraspinatus run, and what joint movement does it help with?

Answer 40

This runs superiorly from the scapula to the top of the humerus and helps with shoulder abduction.

Question 41

Where does the infraspinatus run, and what joint movement does it help with?

Answer 41

This runs laterally from the scapula (slightly higher than the teres minor) to the humerus. It helps with horizontal extension, external rotation and adduction.

Question 42

Where does the subscapularisrun, and what joint movement does it help with?

Answer 42

This runs from the underside of the scapula to the front of the humerus and helps with internal rotation and adduction.

Question 43

Whyat is the Shoulder Girdle comprised of?

Answer 43

Scapulae and Clavicles

Question 44

The upper back of the shoulder girdle is occupied by what muscles?

Answer 44

The trapezius, rhomboids Major and minor | and levator scapulae muscles

Question 45

The pectoralis minor and serratus anterior are part of the anterior musculature of the shoulder girdle. Where do they originate and insert?

Answer 45

They originate from the costal bones and run to the anterior surfaces of the scapulae area.

Question 46

The vertebral column is comprised of a series of what shape of vertebral bones, linked by what type of joints and separated by intervertebral what?.

Answer 46

The vertebral column is comprised of a series of irregular vertebral bones, which are predominantly linked by cartilaginous, slightly movable joints. These are separated by intervertebral discs.

Question 47

Movement of the spine is achieved via which three major muscles of the trunk?

Answer 47

The rectus abdominis, obliques (internal/external) and erector spinae.

Question 48

The musculature of the posterior section of the vertebral column tends to be more complex than elsewhere - Why?

Answer 48

Because of its need for multiple origins and insertions.

Question 49

What are the two important muscles of the posterior musculature?

Answer 49

The multifidus and quadratus lumborum

Question 50

What's the differences between the shoulder and hips in terms of mobility and stability.

Answer 50

The hip joint sacrifices mobility for stability, whereas the shoulder joint sacrifices stability for mobility. The shoulder is, therefore, more prone to dislocation.

Question 51

At the hip, what muscles are invloved with flexion?

Answer 51

The iIiacus or psoas and the rectus femoris

Question 52

At the hip, what muscles are invloved with extension?

Answer 52

The gluteus maximus and hamstrings

Question 53

At the hip, what muscles are invloved with adduction?

Answer 53

The adductor longus, brevis or magnus; the pectineus and gracilis

Question 54

At the hip, what muscles are invloved with abduction?

Answer 54

The piriformis and tensor facia latae; the gluteus minimus or medius

Question 55

What are the four quad muscles?

Answer 55

Rectus fermoris, vastus lateralis, vastus medialis, vastus intermedialis

Question 56

What are the three hamstring muscles?

Answer 56

Biceps femoris, Semimembranosus, Semitendinosus