Elbow And Forearm Flashcards
What is the position of the forearm in passive flexion?
Shoulder in line up with humerus
Occasionally lines up medially
Dictated by the angle of the trochlear groove
What are aspects of the axis of rotation for the humeroulnar/radial joint?
Relatively fixed
Passes through the center of the capitulum and trochlea
What are the aspects of the carrying angle?
In anatomical position, the angle of the trochlea causes the ulna to deviate laterally from the humerus
Gives a normal valgus formation of the forearm on the humerus
What the carry angle for males and females?
Male 5-10
Female 10-15
When does the carry angle disappear?
In pronation or full flexion
What are the deformities that are associated with the carrying angle?
Excessive cubitus valgus occurs around 20 degrees
Cubitus varus occurs when the angle is less than 5 degrees (gunstock deformity)
Which two muscles are two joint muscles?
Biceps and triceps
What occurs when in elbow flexion, and shoulder flexion?
Biceps become actively insufficient
Triceps become passively insufficient
What occurs in elbow extension and shoulder extension
Biceps become passively insufficient
Triceps become actively insufficient
What are the positions of greatest mechanical advantage for biceps brachialis and brachioradialis?
Biceps- elbow flexed to 90-100 degrees
Brachialis-elbow flexed to 100 degree
Brachioradialis-elbow flexed to 100-120 degrees
When is the moment arm greatest for the triceps?
Near 0 degrees
When is the force production greatest for the extensors?
Near 90 degrees
What is as influential as leverage in determining where the peak torque occurs?
Muscle length
Why is muscle length influential in determining torque?
Length tension relationship
When is the brachialis active?
During all types of flexor activity.
Workhorse of the elbow flexors
When are the biceps quiet in flexor activity?
When the forearm is fully pronated
When is the brachioradialis the greatest in muscle activity?
Concentric flexion between 0-60 degrees
Which triceps head does the mot work during unressted extension?
Medial head
What has to occur for all heads of the triceps to fire?
Resisted extension
Which muscle is strongest: flexor or extensor?
flexor
What muscle prevents elbow flexion when the biceps act as supinators?
The triceps
Which muscle stabilizes the elbow during pronation and supination?
Anconeus
Where is the longitudinal axis in the radioulnar joint?
Extends from the radial head to the center of the ulna
In supination what occurs with the radius and ulna?
They are parallel
In pronation what occurs to the radius and ulna?
Radius crosses ulna
What happens with the ulna in general?
Very little motion
What muscles produce and what occurs during pronation?
Pronator teres and pronator quadratus
Exert pull on radius and causes the distal end to rotate over the ulna
What muscles produce and what occurs during supination?
Biceps and supinator
Exert pull on radius which causes the distal end to rotate away from the ulna
What happens with slow unresisted supination?
Only the supinator acts
What happens with resisted fast supination with the elbow flexed to 90 degrees?
Biceps acts
Which muscles are strong: supinator or pronator?
Supinators
Functionally, what is the elbow complex designed for?
Positioning of the hand
What elbow motion is associated with pronation?
Elbow extension
What elbow motion is associated with supination?
Elbow Flexion
What is a greater functional loss: elbow extension or flexion?
Elbow flexion-have to go against gravity
What is a greater functional loss: supinator or pronator?
Supinator
Dealing with tendodesis, what alters the length-tension of the finger flexors and extensors?
Position of the wrist
What will create passive flexion of the fingers?
Active extension of the wrist
What will create passive extension o the fingers?
Active flexion of the wrist
What activates to set the wrist into place to allow the finger flexors to work sufficiently?
Wrist extensors
When the wrist is not in too much flexion or extension, how much more compression forces can be achieved?
20-30 degrees more
What are the power grips?
Cylindrical (hammer)
Spherical (baseball)
Hook (briefcase)
What are the precision grips?
Tip prehension-tip to tip
Palmer prehension-pad to pad
Lateral prehension-pad to side
