Unit 4: Biomechanics of the Upper Limb & Spine

Question 1

What is the major function of the upper limb?

Answer 1

To position the hand in space

Question 2

What are the 3 synoviL articulations of the shoulder joint?

Answer 2

Glenohumeral
Acromioclaviclar
Sternoclavicular

Question 3

What is the fourth bone-on-muscle-on-bone articulation?

Answer 3

Scapulthoracic

Question 4

What forms the glenohumeral joint?

Answer 4

Humeral head & glenoid fossa of the scapula

Question 5

What aids the stability of the glenohumeral joint?

Answer 5

Glenoid labrum (thick cartilaginous rim)
Tharticulation is surrounded by a capsule and rotator cuff

Question 6

What are the 4 muscles that make up the rotator cuff?

Answer 6

Subscapularis
Infraspinatus
Supraspinatus
Teres minor

Question 7

How does the rotator cuff stabilise the joint?

Answer 7

Pushes on the humeral head preventing any anterior-posterior movement

Question 8

What comprises the acromioclavicular joint?

Answer 8

Proximal acromoin of the scapula and distal clavicle

Question 9

What stabilises the AC joint?

Answer 9

Superior & inferior AC ligaments

Coracoclavicular ligament

Question 10

Why is there only a few degrees of motion at AC joint?

Answer 10

Restricted by thorax & muscle attachments

Question 11

What is the only bony joint connnecting the shoulder girdle to the trunk?

Answer 11

Sternoclavicular joint

Question 12

How does the clavicle move as the arm abducts?

Answer 12

Elevates by 4 degrees for every 10 degrees of arm elevation up to 90 degrees then the elevation is negligible

Question 13

What determines the axis around which the clavicle rotates during elevation & depression?

Answer 13

Attachment of the costoclavicular ligament

Question 14

What muscles separate the anterior surface of the scapula from the posterior thorax?

Answer 14

Serratus anterior

Subscapularis

Question 15

What are the origins & insertions of the serratus anterior muscle?

Answer 15

Originates on the upper 8 or 9 ribs and inserts on the anterior surface of the scapula along its vertebral border

Question 16

What is the purpose of the serratus anterior?

Answer 16

Holds scapula against thorax preventing “winging”

Strong abductor useful in pulling or pushing movements

Question 17

What is the origin & insertion of the subscapularis muscle?

Answer 17

Originates from subscapular fossa and inserts on the lesser tubercle of the humerus

Question 18

What is the function of the subscapularis muscle?

Answer 18

Medially rotate the humerus

Question 19

What is shoulder elevation?

Answer 19

Movement of the humerus away from the side of the thorax in any plane

Question 20

What is the normal range of forward flexion and abduction of the shoulder?

Answer 20

180 degrees

Question 21

What is the normal range of backward extension of the shoulder?

Answer 21

60 degrees

Question 22

What is the normal range of adduction with the arm moving in front of the trunk?

Answer 22

75 degrees

Question 23

What is the normal range of horizontal flexion of the shoulder?

Answer 23

135 degrees

Question 24

What is the normal range of horizontal extension of the shoulder?

Answer 24

45 degrees

Question 25

What are the different movements of the shoulder?

Answer 25

Abduction/Adduction Forward flexion/Backward extension Horizontal flexion/Horizontal extension Internal/External rotation

Question 26

What is the range of motion of internal and external rotation of the shoulder?

Answer 26

90 degrees of each

Question 27

What is the most common dislocation of the shoulder?

Answer 27

Anterior dislocation of the glenohumeral articulation

Question 28

In what situation is their mostly likely to be an anterior dislocation of the glenohumeral articulation and why?

Answer 28

Heavy blow when arm is abducted and extended (arm acts as first class lever)

Question 29

What are the 3 synovial articulations of the elbow?

Answer 29

Humeroradial articulation Humeroulnar articulation Proximal radioulnar articulation

Question 30

What forms the humeroradial articulation?

Answer 30

Capitellum of the distal humerus & head of the radius

Question 31

What forms the humeroulnar articulation/

Answer 31

Trochlea of the distal humerus & trochlear fossa of the proximal ulna

Question 32

What forms the proximal radioulnar articulation?

Answer 32

Head of the radius & radial notch of the proximal ulna

Question 33

Where does the axis of rotation pass through in the elbow?

Answer 33

Middle of the trochlea (roughly parallel to the line joining the lateral and medial epicondyles of the humerus)

Question 34

What is the range of flexion-extension of the elbow?

Answer 34

140 degrees

Question 35

Which articulation allows pronation & supination?

Answer 35

Proximal radioulnar articulation

Question 36

How are pronation & supination achieved?

Answer 36

Rotation of the head of the radius in the radial notch of the ulna inside the annular ligament (allows migration of the distal end of radius around the distal end of the ulna)

Question 37

What is the total range of pronation-supination?

Answer 37

150 degrees (70 pronation, 80 supination)

Question 38

What range of motion at the elbow is needed for daily activities?

Answer 38

100 degrees flexion (30-130) | 100 degrees pronation-supination (50-50)`

Question 39

What is the olecranon process and what is it's purpose?

Answer 39

Resembles a spanner - well suited to resist forces in the anteroposterior direction Holds the trochlea like a nut

Question 40

What provides medial & lateral stability in the elbow?

Answer 40

Collateral ligaments (in particular medial CL prevents abduction)

Question 41

Which muscle assists the lateral collateral ligament in the elbow?

Answer 41

Anconeus muscle

Question 42

What is the origin and insertion of the anconeus muscle?

Answer 42

Origin - lateral epicondyle of the humerus | Insertion - olecranon & superior portion of ulnar shaft

Question 43

What is the most likely mechanism for n anterior dislocation of the elbow?

Answer 43

Fall on outstretched hand

Question 44

Why are the joint forces at the elbow large?

Answer 44

arge muscle forces for activities pull the 2 sides of the joinnt together Muscles have small moment arms

Question 45

What are the 8 carpal bones of the wrist?

Answer 45

``` Scaphoid Lunate Triquetrium Pisiform Trapezium Trapezoid Capitate Hamate ```

Question 46

Which is the only carpal bone that is easily palpated?

Answer 46

Pisiform

Question 47

What is the pisiform the insertion point of?

Answer 47

Flexor carpi ulnaris

Question 48

What does flexor carpi ulnaris do?

Answer 48

Flexes and adducts the wrist

Question 49

Why is the pisiform bone important?

Answer 49

Increases the lever arm of the flexor carpi ulnaris

Question 50

What forms the radiocarpal joint?

Answer 50

Articulation of the lunate & scaphoid at the distal end of the radius

Question 51

What is a condyloid joint?

Answer 51

When an oval shaped condyle fits into an elliptical depression

Question 52

What movements does the radiocarpal joint allow?

Answer 52

Flexion & extension Abduction & adduction Circumduction

Question 53

What is found in the ulnocarpal space?

Answer 53

Triquetrium articulates with the distal ulna (attached at its apex to styloid process of the ulna & at base to ulnar notch of the radius)

Question 54

What degree of flexion does the wrist allow?

Answer 54

80-90 degrees

Question 55

What degree of extension does the wrist allow?

Answer 55

70-80 degrees

Question 56

At which joint does 60% of flexion occur?

Answer 56

Midcarpal joint

Question 57

At which joint does 67% of extension occur?

Answer 57

Radiocarpal joint

Question 58

What degree of abduction does the wrist joint allow?

Answer 58

15-20 degrees

Question 59

What degree of adduction does the wrist allow?

Answer 59

35 degrees

Question 60

What range of motion of the wrist is needed for daily activities?

Answer 60

10 flex - 35 extension

Question 61

If the wrist joint is fused what position provides best functional capacity?

Answer 61

Fixed extension of 15 degrees

Question 62

Which is the most free moving CMC joint?

Answer 62

First carpometacarpal joint (between trapezium and first MC)

Question 63

What is the significance of the the first CMC joint?

Answer 63

Allows the thumb to oppose fingers (saddle joint)

Question 64

What type of joint are MCP joints?

Answer 64

Condyloid joints (rounded distal heads of the metacarpals and the concave proximal ends of the phalanges)

Question 65

What type of joint are the PIPs & DIPs?

Answer 65

Hinge joints

Question 66

What is the maximum amount of flexion the MCP's are capable of?

Answer 66

90 degrees

Question 67

What is the maximum amount of flexion possible at the PIPs?

Answer 67

100-110 degrees

Question 68

What is the maximum amount of flexion at the DIPs?

Answer 68

90 degrees

Question 69

What is flexion & extension of the thumb?

Answer 69

``` Flexion = moves across the palm Extension = moves away from the side of the palm ```

Question 70

What is the range of flexion & extension of the thumb?

Answer 70

15 degrees flexion | 20 degrees extension

Question 71

What degree of abduction is the thumb capable of?

Answer 71

60 degrees

Question 72

Where are the principles muscles that control the movements of the digits located?

Answer 72

The forearm

Question 73

What is the origin & insertion of the flexor digitorum profundus?

Answer 73

Origin - anterior aspect of ulna | Insertion - distal phalanges

Question 74

What is the function of the flexor digitorum profundus?

Answer 74

Flexes the DIPs

Question 75

How many vertebrae make up the spine?

Answer 75

7 cervical 12 thoracic (dorsal) 5 lumbar 5 sacral & 4 coccyx (fused)

Question 76

What are the 3 points of articulation between vertebrae?

Answer 76

Via intervertebral discs | 2 facet joints

Question 77

What is the nucleus pulposus?

Answer 77

Lies at the centre of discs Formed by strongly hydrophilic gel enmeshed in a random collagen matrix Internal pressure balances the applied compressive stress (water movement to compensate)

Question 78

What is the annulus fibrosus?

Answer 78

Tough layer which surrounds the nucelus pulposus Composed of collagen fibres which form lamellae This arrangement resists high bending & torsional loads

Question 79

Describe the structure of the axis (C2)

Answer 79

Has a dens process which protrudes superiorly from the body

Question 80

Describe the structure of the axis (C1)

Answer 80

Has no body but is composed of a ring within which an oval fossa articulates with the axis

Question 81

At what region of the spine is the greatest flexion possible?

Answer 81

Cervical spine

Question 82

What is the total range of flexion between C4 & C5?

Answer 82

21 degrees

Question 83

At what region of the spine is the least flexion possible?

Answer 83

Thoracic spine (3 degrees between T9/10)

Question 84

Which segments of the spine are most and least mobile when lateral bending?

Answer 84

Most mobile = cervical | Least mobile = thoracic

Question 85

At which point in the spine is there no lateral bending?

Answer 85

Between C1 & C2

Question 86

At which point in the spine is there most rotation?

Answer 86

Between C1 & C2 (decreases going down the spine)

Question 87

As the moment arm of the upper body weight increases does the loading on the spine increase or decrease?

Answer 87

Load on the spine increases as the moment arm increases