Biomech unit 4 SAQ's

Question 1

List the four articulations of the shoulder joint

Answer 1

1. Glenohumeral
2. Acromioclavicular
3. Sternoclavicular
4. Scapulothoracic

Question 2

Name the shallow depression in which the humeral head rests

Answer 2

Glenoid fossa

Question 3

Why is the scapulothoracic articulation not a joint in the truest sense?

Answer 3

Because there are no direct bony or ligamentous connections between the scapula and thorax.

Question 4

Name the ligament about whose attachment the clavicle rotates during elevation and depression.

Answer 4

Costoclavicular ligament

Question 5

Complete the following table:

Answer 5

Question 6

If, in the above examination of the mechanics of anterior dislocation of the glenohumeral articulation, the magnitude of the applied force was 100 N, what must the magnitude of the resistance force be if it is to prevent a dislocation?

Answer 6

R = 1000N

==> the resistance force must be 10 times that of the applied force to prevent dislocation (as the applied force is working at a MA of 10)

Refer to unit 4 SAQ’s and worked examples for the written out ans

Question 7

Complete the following table of the maximum ranges of motion of the elbow

Answer 7

Question 8

By sketching a diagram of the arm decide which ligament will prevent an elbow dislocating in a fall to the side with the arm straight so that it breaks the fall.

Answer 8

Question 9

List the bones that form the proximal and distal rows of the wrist.

Answer 9

The bones that form the proximal row of the wrist are the triquetrum, lunate and scaphoid and those that form the distal row are the hamate, capitate, trapezoid and trapezium

Question 10

How is the lever arm of the flexor carpi ulnaris muscle increased?

Answer 10

The lever arm of the flexor carpi ulnaris muscle is increased by the pisiform bone

Question 11

What are the principal motions of the wrist joint?

Answer 11

Flexion-extension and abduction-adduction.

Question 12

At which articulation does most wrist extension occur?

Answer 12

The radiocarpal joint.

Question 13

What is the most functional position for an immobilised wrist joint?

Answer 13

15 degrees of extension.

Question 14

How does the maximum amount of flexion at the metacarpophalangeal joint vary from finger to finger?

Answer 14

• The maximum amount of flexion at the MCP joints generally decreases from the fifth to the second joint.
• At the fifth joint (little finger) it is around 95 to 100 degrees and at the second joint (index finger) it is about 70 degrees.

Question 15

Name the five regions of the spine.

Answer 15

1. cervical
2. thoracic
3. lumbar
4. sacrum
5. coccyx

Question 16

Try to estimate the amount of range of rotation in your lumbar and thoracic spine. First of all stand up in front of a wall with your arms folded and twist gently from side to side whilst keeping your arms fixed relative to your chest. Note, how the angle between your folded arms and the wall changes. Does this give a true representation of the range of rotation in your lumbar and thoracic spine?

Answer 16

No. When standing and gently twisting from side to side, motion also occurs in the lower limbs. Do the same again but this time sitting down. This should give you a better estimate of the range of rotation in your lumbar and thoracic spine.

Question 17

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

Answer 17

The loading on the spine increases as the moment arm of the upper body weight increases.