Elbows, Wrist, Hands

Question 1

Elbow - levers

Answer 1

• A lever system is made up of three parts, an effort, a load, and a fulcrum.
• In the human body, the effort is provided by the muscle (the muscles point of application/insertion), the load is the weight of the body and any additional resistance, and the fulcrum is the joint itself.
• The Elbow is an example of a 3rd class lever during flexion - FEL

Question 2

Flexion torque during pronation/ supination

Answer 2

• Flexion torques are 70% greater than extension torque. The torque force needed for a bicep curl is 70% greater than an extension push down.
• Flexion torque with supination is 20% greater than with pronation.
• Brachioradialis in the mid prone (bowstringing) increases the power of flexion during last 80-90deg

Question 3

Roll and slide

Answer 3

• The Ulnar is the concave surface
• The Humerus is the convex surface.
• The humerus is passive in both flexion and extension, which is driven by active movement of the ulnar and radius.
• On elbow flexion the roll and slide move in the same direction.
• Radius will roll and ulnar will slide in the direction of the radius during pronation and supernation, both move in the same direction.

Question 4

Kinematics of pronation and supination

Answer 4

• Pivot shape of radial head controlled by the annular ligament and interosseous membrane

Question 5

Purpose of interosseous membrane

Answer 5

stabilises the two bones and allows for controlled movement of supernation and pronation. Otherwise, you could take the bones 360deg creating lots of problems. Thick form of fascial tissue, at the distal end has a syndesmosis, thickens up, almost becoming a ligament to ensure there’s no shearing between the ulnar and radial head

Question 6

What is significant about its structure

Answer 6

Cross fibres, creates strong and flexible structure, allowing it to cope with multi vectors of movement. Also has apertures, little holes allowing for blood vessels and nerves to pass through.

Question 7

Wrist; roll and slide mechanism

Answer 7

• Ulnar and radial deviation.
• The radius is the concave structure.
• The Proximal carpals are the convex structures.
• Movement driven actively by carpals, and passively allowed by distal radius and ulnar

Question 8

Hand – Grip, What’s special about the lumbricals

Answer 8

give ability to flex at the metacarpal phalangeal joint, whilst at the same time to extend at the interphalangeal joint
* Opposition makes us different from other mammals