DITHM EXAM - WEEK 5 - Lower and Upper Limb biomechanics

Question 1

Name the joints and muscles involved in pronation of the forearm.

Answer 1

Joints:
Proximal Radioulnar Joint.
Distal Radioulnar Joint.

Muscles:
Pronator teres

Pronator quadratus

Flexor capri radialis

Question 2

Name the only joint that joins the upper limb to the axial skeleton.

Answer 2

Sternoclavicular joint.

Question 3

Explain scapulohumeral rhythm – the various joints, their ranges of motion and the
interplay in creating shoulder abduction.

Answer 3

Scapulohumeral rhythm in shoulder abduction:
- Glenohumeral joint contributes 120 degrees abduction
- Scapulothoracic joint contributes to 60 degrees rotation

These two joints work in a 2:1 ratio, with the GHJ moving more initially, followed by both joints together to complete abduction.

Question 4

What is the role of the meniscus of the knee?

Answer 4

• Joint stability
• Shock absorption
• Weight distribution / Load transmission
• Proprioception (position awareness)

Question 5

What is the role of the ACL, PCL and collateral ligaments of the knee?

Answer 5

ACL:
Limits:
- Anterior displacement of tibia under a fixed femur.
- Hyperextension
- Internal femoral rotation on a fixed tibia

PCL:
Limits:
- Posterior displacement of a tibia under a fixed femur.
- Hyperflexion
- External femoral rotation on a fixed tibia.

MCL:
- Medial and Lateral translation of tibia under a fixed femur.
- Valgus stress.

Question 6

What is the angle of inclination and it’s ranges for classification?

Answer 6

Angle taken between the long axis of the femoral neck and the long axis of the femoral shaft.

Coxa Vara: angle less then 110 - 120 degrees.
Coxa Valga - angle more then 130 - 135 degrees.

Question 7

What is the angle of torsion and it’s ranges for classification? What type of posture is created by increased and decreased torsion?

Answer 7

Angle between the long axis and the femoral neck and a line touching the posterior borders of the femoral condyles.
- Varies between 10 - 15 degrees.

Femoral anteversion - pathological increase in angle of torsion.
- “Pigeon - toad”

Femoral retroversion - pathological decrease in angle of torsion.

Question 8

List the muscles involved with each range of motion of the Humeroulnar joint.

Answer 8

Flexion:
Biceps brachii
Brachialis
Brachioradialis

Extension:
- Triceps brachii

Question 9

List the muscles involved with each range of motion of the Glenohumeral joint.

Answer 9

Flexion:
- Pectoralis major
- Deltoid (anterior fibers)
- Coracobrachialis
- Biceps brachii (long head)

Extension:
- Latissimus dorsi
- Teres major
- Deltoid (posterior fibers)
- Triceps brachii (long head)

Abduction:
- Deltoid
- Supraspinatus

Adduction:
- Pectoralis major
- Latissimus dorsi
- Teres major
- Coracobrachialis

Internal Rotation:
- Subscapularis
- Teres major
- Latissimus dorsi
- Pectoralis major
- Deltoid (anterior fibers)

External Rotation:
- Infraspinatus
- Teres minor
- Deltoid (posterior fibers)

Question 10

List the muscles involved with each range of motion of the Radioulnar joint.

Answer 10

Pronation:
- Pronator teres
- Pronator quadratus

Supination:
- Supinator
- Biceps brachii

Question 11

List the muscles involved with each range of motion of the Radiocarpal joint. (wrist)

Answer 11

Flexion:
- Flexor carpi radialis
- Flexor carpi ulnaris
- Palmaris longus
- Flexor digitorum superficialis
- Flexor digitorum profundus

Extension:
- Extensor carpi radialis longus
- Extensor carpi radialis brevis
- Extensor carpi ulnaris
- Extensor digitorum

Radial Deviation (Abduction)
- Extensor carpi radialis longus & brevis
- Flexor carpi radialis
- Abductor pollicis longus

Ulnar Deviation (Adduction)
- Extensor carpi ulnaris
- Flexor carpi ulnaris

Question 12

List the muscles involved with each range of motion of the Iliofemoral joint. (Hip)

Answer 12

Flexion:
- Psoas
- Iliacus
- Rectus femoris

Extension:
- Gluteus maximus
- Hamstrings
(Semimembranosus, Semitendinosus, Biceps femoris)
- Adductor magnus

Abduction:
- Gluteus medius
- Gluteus minimus
- Tensor fascia latae (TFL)

Adduction:
- Adductor magnus
- Adductor longus
- Adductor brevis

Internal rotation:
- Gluteus medius
- Gluteus minimus

External rotation
- Piriformis
- Gluteus maximus
- Obturator internus
- Gemelli superior & inferior
- Quadratus femoris

Question 13

List the muscles involved with each range of motion of the tibiofemoral joint. (Knee)

Answer 13

Flexion:
- Hamstrings (Semimembranosis,
Semitendinosis, Biceps femoris)

Extension:
- Quadriceps femoris (Rectus femoris, Vastus medialis, Vastus intermedialis, Vastus lateralis)

Medial/Lateral rotation:
- Popliteus
- Semimembranosis
- Semitendinosis